hgbook

annotate es/collab.tex @ 404:1839fd383e50

translated a few subsections of intro
author Igor TAmara <igor@tamarapatino.org>
date Sat Nov 08 21:47:35 2008 -0500 (2008-11-08)
parents 04c08ad7e92e
children a9ea523446cc
rev   line source
igor@402 1 \chapter{Collaborating with other people}
igor@402 2 \label{cha:collab}
igor@402 3
igor@402 4 As a completely decentralised tool, Mercurial doesn't impose any
igor@402 5 policy on how people ought to work with each other. However, if
igor@402 6 you're new to distributed revision control, it helps to have some
igor@402 7 tools and examples in mind when you're thinking about possible
igor@402 8 workflow models.
igor@402 9
igor@402 10 \section{Mercurial's web interface}
igor@402 11
igor@402 12 Mercurial has a powerful web interface that provides several
igor@402 13 useful capabilities.
igor@402 14
igor@402 15 For interactive use, the web interface lets you browse a single
igor@402 16 repository or a collection of repositories. You can view the history
igor@402 17 of a repository, examine each change (comments and diffs), and view
igor@402 18 the contents of each directory and file.
igor@402 19
igor@402 20 Also for human consumption, the web interface provides an RSS feed of
igor@402 21 the changes in a repository. This lets you ``subscribe'' to a
igor@402 22 repository using your favourite feed reader, and be automatically
igor@402 23 notified of activity in that repository as soon as it happens. I find
igor@402 24 this capability much more convenient than the model of subscribing to
igor@402 25 a mailing list to which notifications are sent, as it requires no
igor@402 26 additional configuration on the part of whoever is serving the
igor@402 27 repository.
igor@402 28
igor@402 29 The web interface also lets remote users clone a repository, pull
igor@402 30 changes from it, and (when the server is configured to permit it) push
igor@402 31 changes back to it. Mercurial's HTTP tunneling protocol aggressively
igor@402 32 compresses data, so that it works efficiently even over low-bandwidth
igor@402 33 network connections.
igor@402 34
igor@402 35 The easiest way to get started with the web interface is to use your
igor@402 36 web browser to visit an existing repository, such as the master
igor@402 37 Mercurial repository at
igor@402 38 \url{http://www.selenic.com/repo/hg?style=gitweb}.
igor@402 39
igor@402 40 If you're interested in providing a web interface to your own
igor@402 41 repositories, Mercurial provides two ways to do this. The first is
igor@402 42 using the \hgcmd{serve} command, which is best suited to short-term
igor@402 43 ``lightweight'' serving. See section~\ref{sec:collab:serve} below for
igor@402 44 details of how to use this command. If you have a long-lived
igor@402 45 repository that you'd like to make permanently available, Mercurial
igor@402 46 has built-in support for the CGI (Common Gateway Interface) standard,
igor@402 47 which all common web servers support. See
igor@402 48 section~\ref{sec:collab:cgi} for details of CGI configuration.
igor@402 49
igor@402 50 \section{Collaboration models}
igor@402 51
igor@402 52 With a suitably flexible tool, making decisions about workflow is much
igor@402 53 more of a social engineering challenge than a technical one.
igor@402 54 Mercurial imposes few limitations on how you can structure the flow of
igor@402 55 work in a project, so it's up to you and your group to set up and live
igor@402 56 with a model that matches your own particular needs.
igor@402 57
igor@402 58 \subsection{Factors to keep in mind}
igor@402 59
igor@402 60 The most important aspect of any model that you must keep in mind is
igor@402 61 how well it matches the needs and capabilities of the people who will
igor@402 62 be using it. This might seem self-evident; even so, you still can't
igor@402 63 afford to forget it for a moment.
igor@402 64
igor@402 65 I once put together a workflow model that seemed to make perfect sense
igor@402 66 to me, but that caused a considerable amount of consternation and
igor@402 67 strife within my development team. In spite of my attempts to explain
igor@402 68 why we needed a complex set of branches, and how changes ought to flow
igor@402 69 between them, a few team members revolted. Even though they were
igor@402 70 smart people, they didn't want to pay attention to the constraints we
igor@402 71 were operating under, or face the consequences of those constraints in
igor@402 72 the details of the model that I was advocating.
igor@402 73
igor@402 74 Don't sweep foreseeable social or technical problems under the rug.
igor@402 75 Whatever scheme you put into effect, you should plan for mistakes and
igor@402 76 problem scenarios. Consider adding automated machinery to prevent, or
igor@402 77 quickly recover from, trouble that you can anticipate. As an example,
igor@402 78 if you intend to have a branch with not-for-release changes in it,
igor@402 79 you'd do well to think early about the possibility that someone might
igor@402 80 accidentally merge those changes into a release branch. You could
igor@402 81 avoid this particular problem by writing a hook that prevents changes
igor@402 82 from being merged from an inappropriate branch.
igor@402 83
igor@402 84 \subsection{Informal anarchy}
igor@402 85
igor@402 86 I wouldn't suggest an ``anything goes'' approach as something
igor@402 87 sustainable, but it's a model that's easy to grasp, and it works
igor@402 88 perfectly well in a few unusual situations.
igor@402 89
igor@402 90 As one example, many projects have a loose-knit group of collaborators
igor@402 91 who rarely physically meet each other. Some groups like to overcome
igor@402 92 the isolation of working at a distance by organising occasional
igor@402 93 ``sprints''. In a sprint, a number of people get together in a single
igor@402 94 location (a company's conference room, a hotel meeting room, that kind
igor@402 95 of place) and spend several days more or less locked in there, hacking
igor@402 96 intensely on a handful of projects.
igor@402 97
igor@402 98 A sprint is the perfect place to use the \hgcmd{serve} command, since
igor@402 99 \hgcmd{serve} does not requires any fancy server infrastructure. You
igor@402 100 can get started with \hgcmd{serve} in moments, by reading
igor@402 101 section~\ref{sec:collab:serve} below. Then simply tell the person
igor@402 102 next to you that you're running a server, send the URL to them in an
igor@402 103 instant message, and you immediately have a quick-turnaround way to
igor@402 104 work together. They can type your URL into their web browser and
igor@402 105 quickly review your changes; or they can pull a bugfix from you and
igor@402 106 verify it; or they can clone a branch containing a new feature and try
igor@402 107 it out.
igor@402 108
igor@402 109 The charm, and the problem, with doing things in an ad hoc fashion
igor@402 110 like this is that only people who know about your changes, and where
igor@402 111 they are, can see them. Such an informal approach simply doesn't
igor@402 112 scale beyond a handful people, because each individual needs to know
igor@402 113 about $n$ different repositories to pull from.
igor@402 114
igor@402 115 \subsection{A single central repository}
igor@402 116
igor@402 117 For smaller projects migrating from a centralised revision control
igor@402 118 tool, perhaps the easiest way to get started is to have changes flow
igor@402 119 through a single shared central repository. This is also the
igor@402 120 most common ``building block'' for more ambitious workflow schemes.
igor@402 121
igor@402 122 Contributors start by cloning a copy of this repository. They can
igor@402 123 pull changes from it whenever they need to, and some (perhaps all)
igor@402 124 developers have permission to push a change back when they're ready
igor@402 125 for other people to see it.
igor@402 126
igor@402 127 Under this model, it can still often make sense for people to pull
igor@402 128 changes directly from each other, without going through the central
igor@402 129 repository. Consider a case in which I have a tentative bug fix, but
igor@402 130 I am worried that if I were to publish it to the central repository,
igor@402 131 it might subsequently break everyone else's trees as they pull it. To
igor@402 132 reduce the potential for damage, I can ask you to clone my repository
igor@402 133 into a temporary repository of your own and test it. This lets us put
igor@402 134 off publishing the potentially unsafe change until it has had a little
igor@402 135 testing.
igor@402 136
igor@402 137 In this kind of scenario, people usually use the \command{ssh}
igor@402 138 protocol to securely push changes to the central repository, as
igor@402 139 documented in section~\ref{sec:collab:ssh}. It's also usual to
igor@402 140 publish a read-only copy of the repository over HTTP using CGI, as in
igor@402 141 section~\ref{sec:collab:cgi}. Publishing over HTTP satisfies the
igor@402 142 needs of people who don't have push access, and those who want to use
igor@402 143 web browsers to browse the repository's history.
igor@402 144
igor@402 145 \subsection{Working with multiple branches}
igor@402 146
igor@402 147 Projects of any significant size naturally tend to make progress on
igor@402 148 several fronts simultaneously. In the case of software, it's common
igor@402 149 for a project to go through periodic official releases. A release
igor@402 150 might then go into ``maintenance mode'' for a while after its first
igor@402 151 publication; maintenance releases tend to contain only bug fixes, not
igor@402 152 new features. In parallel with these maintenance releases, one or
igor@402 153 more future releases may be under development. People normally use
igor@402 154 the word ``branch'' to refer to one of these many slightly different
igor@402 155 directions in which development is proceeding.
igor@402 156
igor@402 157 Mercurial is particularly well suited to managing a number of
igor@402 158 simultaneous, but not identical, branches. Each ``development
igor@402 159 direction'' can live in its own central repository, and you can merge
igor@402 160 changes from one to another as the need arises. Because repositories
igor@402 161 are independent of each other, unstable changes in a development
igor@402 162 branch will never affect a stable branch unless someone explicitly
igor@402 163 merges those changes in.
igor@402 164
igor@402 165 Here's an example of how this can work in practice. Let's say you
igor@402 166 have one ``main branch'' on a central server.
igor@402 167 \interaction{branching.init}
igor@402 168 People clone it, make changes locally, test them, and push them back.
igor@402 169
igor@402 170 Once the main branch reaches a release milestone, you can use the
igor@402 171 \hgcmd{tag} command to give a permanent name to the milestone
igor@402 172 revision.
igor@402 173 \interaction{branching.tag}
igor@402 174 Let's say some ongoing development occurs on the main branch.
igor@402 175 \interaction{branching.main}
igor@402 176 Using the tag that was recorded at the milestone, people who clone
igor@402 177 that repository at any time in the future can use \hgcmd{update} to
igor@402 178 get a copy of the working directory exactly as it was when that tagged
igor@402 179 revision was committed.
igor@402 180 \interaction{branching.update}
igor@402 181
igor@402 182 In addition, immediately after the main branch is tagged, someone can
igor@402 183 then clone the main branch on the server to a new ``stable'' branch,
igor@402 184 also on the server.
igor@402 185 \interaction{branching.clone}
igor@402 186
igor@402 187 Someone who needs to make a change to the stable branch can then clone
igor@402 188 \emph{that} repository, make their changes, commit, and push their
igor@402 189 changes back there.
igor@402 190 \interaction{branching.stable}
igor@402 191 Because Mercurial repositories are independent, and Mercurial doesn't
igor@402 192 move changes around automatically, the stable and main branches are
igor@402 193 \emph{isolated} from each other. The changes that you made on the
igor@402 194 main branch don't ``leak'' to the stable branch, and vice versa.
igor@402 195
igor@402 196 You'll often want all of your bugfixes on the stable branch to show up
igor@402 197 on the main branch, too. Rather than rewrite a bugfix on the main
igor@402 198 branch, you can simply pull and merge changes from the stable to the
igor@402 199 main branch, and Mercurial will bring those bugfixes in for you.
igor@402 200 \interaction{branching.merge}
igor@402 201 The main branch will still contain changes that are not on the stable
igor@402 202 branch, but it will also contain all of the bugfixes from the stable
igor@402 203 branch. The stable branch remains unaffected by these changes.
igor@402 204
igor@402 205 \subsection{Feature branches}
igor@402 206
igor@402 207 For larger projects, an effective way to manage change is to break up
igor@402 208 a team into smaller groups. Each group has a shared branch of its
igor@402 209 own, cloned from a single ``master'' branch used by the entire
igor@402 210 project. People working on an individual branch are typically quite
igor@402 211 isolated from developments on other branches.
igor@402 212
igor@402 213 \begin{figure}[ht]
igor@402 214 \centering
igor@402 215 \grafix{feature-branches}
igor@402 216 \caption{Feature branches}
igor@402 217 \label{fig:collab:feature-branches}
igor@402 218 \end{figure}
igor@402 219
igor@402 220 When a particular feature is deemed to be in suitable shape, someone
igor@402 221 on that feature team pulls and merges from the master branch into the
igor@402 222 feature branch, then pushes back up to the master branch.
igor@402 223
igor@402 224 \subsection{The release train}
igor@402 225
igor@402 226 Some projects are organised on a ``train'' basis: a release is
igor@402 227 scheduled to happen every few months, and whatever features are ready
igor@402 228 when the ``train'' is ready to leave are allowed in.
igor@402 229
igor@402 230 This model resembles working with feature branches. The difference is
igor@402 231 that when a feature branch misses a train, someone on the feature team
igor@402 232 pulls and merges the changes that went out on that train release into
igor@402 233 the feature branch, and the team continues its work on top of that
igor@402 234 release so that their feature can make the next release.
igor@402 235
igor@402 236 \subsection{The Linux kernel model}
igor@402 237
igor@402 238 The development of the Linux kernel has a shallow hierarchical
igor@402 239 structure, surrounded by a cloud of apparent chaos. Because most
igor@402 240 Linux developers use \command{git}, a distributed revision control
igor@402 241 tool with capabilities similar to Mercurial, it's useful to describe
igor@402 242 the way work flows in that environment; if you like the ideas, the
igor@402 243 approach translates well across tools.
igor@402 244
igor@402 245 At the center of the community sits Linus Torvalds, the creator of
igor@402 246 Linux. He publishes a single source repository that is considered the
igor@402 247 ``authoritative'' current tree by the entire developer community.
igor@402 248 Anyone can clone Linus's tree, but he is very choosy about whose trees
igor@402 249 he pulls from.
igor@402 250
igor@402 251 Linus has a number of ``trusted lieutenants''. As a general rule, he
igor@402 252 pulls whatever changes they publish, in most cases without even
igor@402 253 reviewing those changes. Some of those lieutenants are generally
igor@402 254 agreed to be ``maintainers'', responsible for specific subsystems
igor@402 255 within the kernel. If a random kernel hacker wants to make a change
igor@402 256 to a subsystem that they want to end up in Linus's tree, they must
igor@402 257 find out who the subsystem's maintainer is, and ask that maintainer to
igor@402 258 take their change. If the maintainer reviews their changes and agrees
igor@402 259 to take them, they'll pass them along to Linus in due course.
igor@402 260
igor@402 261 Individual lieutenants have their own approaches to reviewing,
igor@402 262 accepting, and publishing changes; and for deciding when to feed them
igor@402 263 to Linus. In addition, there are several well known branches that
igor@402 264 people use for different purposes. For example, a few people maintain
igor@402 265 ``stable'' repositories of older versions of the kernel, to which they
igor@402 266 apply critical fixes as needed. Some maintainers publish multiple
igor@402 267 trees: one for experimental changes; one for changes that they are
igor@402 268 about to feed upstream; and so on. Others just publish a single
igor@402 269 tree.
igor@402 270
igor@402 271 This model has two notable features. The first is that it's ``pull
igor@402 272 only''. You have to ask, convince, or beg another developer to take a
igor@402 273 change from you, because there are almost no trees to which more than
igor@402 274 one person can push, and there's no way to push changes into a tree
igor@402 275 that someone else controls.
igor@402 276
igor@402 277 The second is that it's based on reputation and acclaim. If you're an
igor@402 278 unknown, Linus will probably ignore changes from you without even
igor@402 279 responding. But a subsystem maintainer will probably review them, and
igor@402 280 will likely take them if they pass their criteria for suitability.
igor@402 281 The more ``good'' changes you contribute to a maintainer, the more
igor@402 282 likely they are to trust your judgment and accept your changes. If
igor@402 283 you're well-known and maintain a long-lived branch for something Linus
igor@402 284 hasn't yet accepted, people with similar interests may pull your
igor@402 285 changes regularly to keep up with your work.
igor@402 286
igor@402 287 Reputation and acclaim don't necessarily cross subsystem or ``people''
igor@402 288 boundaries. If you're a respected but specialised storage hacker, and
igor@402 289 you try to fix a networking bug, that change will receive a level of
igor@402 290 scrutiny from a network maintainer comparable to a change from a
igor@402 291 complete stranger.
igor@402 292
igor@402 293 To people who come from more orderly project backgrounds, the
igor@402 294 comparatively chaotic Linux kernel development process often seems
igor@402 295 completely insane. It's subject to the whims of individuals; people
igor@402 296 make sweeping changes whenever they deem it appropriate; and the pace
igor@402 297 of development is astounding. And yet Linux is a highly successful,
igor@402 298 well-regarded piece of software.
igor@402 299
igor@402 300 \subsection{Pull-only versus shared-push collaboration}
igor@402 301
igor@402 302 A perpetual source of heat in the open source community is whether a
igor@402 303 development model in which people only ever pull changes from others
igor@402 304 is ``better than'' one in which multiple people can push changes to a
igor@402 305 shared repository.
igor@402 306
igor@402 307 Typically, the backers of the shared-push model use tools that
igor@402 308 actively enforce this approach. If you're using a centralised
igor@402 309 revision control tool such as Subversion, there's no way to make a
igor@402 310 choice over which model you'll use: the tool gives you shared-push,
igor@402 311 and if you want to do anything else, you'll have to roll your own
igor@402 312 approach on top (such as applying a patch by hand).
igor@402 313
igor@402 314 A good distributed revision control tool, such as Mercurial, will
igor@402 315 support both models. You and your collaborators can then structure
igor@402 316 how you work together based on your own needs and preferences, not on
igor@402 317 what contortions your tools force you into.
igor@402 318
igor@402 319 \subsection{Where collaboration meets branch management}
igor@402 320
igor@402 321 Once you and your team set up some shared repositories and start
igor@402 322 propagating changes back and forth between local and shared repos, you
igor@402 323 begin to face a related, but slightly different challenge: that of
igor@402 324 managing the multiple directions in which your team may be moving at
igor@402 325 once. Even though this subject is intimately related to how your team
igor@402 326 collaborates, it's dense enough to merit treatment of its own, in
igor@402 327 chapter~\ref{chap:branch}.
igor@402 328
igor@402 329 \section{The technical side of sharing}
igor@402 330
igor@402 331 The remainder of this chapter is devoted to the question of serving
igor@402 332 data to your collaborators.
igor@402 333
igor@402 334 \section{Informal sharing with \hgcmd{serve}}
igor@402 335 \label{sec:collab:serve}
igor@402 336
igor@402 337 Mercurial's \hgcmd{serve} command is wonderfully suited to small,
igor@402 338 tight-knit, and fast-paced group environments. It also provides a
igor@402 339 great way to get a feel for using Mercurial commands over a network.
igor@402 340
igor@402 341 Run \hgcmd{serve} inside a repository, and in under a second it will
igor@402 342 bring up a specialised HTTP server; this will accept connections from
igor@402 343 any client, and serve up data for that repository until you terminate
igor@402 344 it. Anyone who knows the URL of the server you just started, and can
igor@402 345 talk to your computer over the network, can then use a web browser or
igor@402 346 Mercurial to read data from that repository. A URL for a
igor@402 347 \hgcmd{serve} instance running on a laptop is likely to look something
igor@402 348 like \Verb|http://my-laptop.local:8000/|.
igor@402 349
igor@402 350 The \hgcmd{serve} command is \emph{not} a general-purpose web server.
igor@402 351 It can do only two things:
igor@402 352 \begin{itemize}
igor@402 353 \item Allow people to browse the history of the repository it's
igor@402 354 serving, from their normal web browsers.
igor@402 355 \item Speak Mercurial's wire protocol, so that people can
igor@402 356 \hgcmd{clone} or \hgcmd{pull} changes from that repository.
igor@402 357 \end{itemize}
igor@402 358 In particular, \hgcmd{serve} won't allow remote users to \emph{modify}
igor@402 359 your repository. It's intended for read-only use.
igor@402 360
igor@402 361 If you're getting started with Mercurial, there's nothing to prevent
igor@402 362 you from using \hgcmd{serve} to serve up a repository on your own
igor@402 363 computer, then use commands like \hgcmd{clone}, \hgcmd{incoming}, and
igor@402 364 so on to talk to that server as if the repository was hosted remotely.
igor@402 365 This can help you to quickly get acquainted with using commands on
igor@402 366 network-hosted repositories.
igor@402 367
igor@402 368 \subsection{A few things to keep in mind}
igor@402 369
igor@402 370 Because it provides unauthenticated read access to all clients, you
igor@402 371 should only use \hgcmd{serve} in an environment where you either don't
igor@402 372 care, or have complete control over, who can access your network and
igor@402 373 pull data from your repository.
igor@402 374
igor@402 375 The \hgcmd{serve} command knows nothing about any firewall software
igor@402 376 you might have installed on your system or network. It cannot detect
igor@402 377 or control your firewall software. If other people are unable to talk
igor@402 378 to a running \hgcmd{serve} instance, the second thing you should do
igor@402 379 (\emph{after} you make sure that they're using the correct URL) is
igor@402 380 check your firewall configuration.
igor@402 381
igor@402 382 By default, \hgcmd{serve} listens for incoming connections on
igor@402 383 port~8000. If another process is already listening on the port you
igor@402 384 want to use, you can specify a different port to listen on using the
igor@402 385 \hgopt{serve}{-p} option.
igor@402 386
igor@402 387 Normally, when \hgcmd{serve} starts, it prints no output, which can be
igor@402 388 a bit unnerving. If you'd like to confirm that it is indeed running
igor@402 389 correctly, and find out what URL you should send to your
igor@402 390 collaborators, start it with the \hggopt{-v} option.
igor@402 391
igor@402 392 \section{Using the Secure Shell (ssh) protocol}
igor@402 393 \label{sec:collab:ssh}
igor@402 394
igor@402 395 You can pull and push changes securely over a network connection using
igor@402 396 the Secure Shell (\texttt{ssh}) protocol. To use this successfully,
igor@402 397 you may have to do a little bit of configuration on the client or
igor@402 398 server sides.
igor@402 399
igor@402 400 If you're not familiar with ssh, it's a network protocol that lets you
igor@402 401 securely communicate with another computer. To use it with Mercurial,
igor@402 402 you'll be setting up one or more user accounts on a server so that
igor@402 403 remote users can log in and execute commands.
igor@402 404
igor@402 405 (If you \emph{are} familiar with ssh, you'll probably find some of the
igor@402 406 material that follows to be elementary in nature.)
igor@402 407
igor@402 408 \subsection{How to read and write ssh URLs}
igor@402 409
igor@402 410 An ssh URL tends to look like this:
igor@402 411 \begin{codesample2}
igor@402 412 ssh://bos@hg.serpentine.com:22/hg/hgbook
igor@402 413 \end{codesample2}
igor@402 414 \begin{enumerate}
igor@402 415 \item The ``\texttt{ssh://}'' part tells Mercurial to use the ssh
igor@402 416 protocol.
igor@402 417 \item The ``\texttt{bos@}'' component indicates what username to log
igor@402 418 into the server as. You can leave this out if the remote username
igor@402 419 is the same as your local username.
igor@402 420 \item The ``\texttt{hg.serpentine.com}'' gives the hostname of the
igor@402 421 server to log into.
igor@402 422 \item The ``:22'' identifies the port number to connect to the server
igor@402 423 on. The default port is~22, so you only need to specify this part
igor@402 424 if you're \emph{not} using port~22.
igor@402 425 \item The remainder of the URL is the local path to the repository on
igor@402 426 the server.
igor@402 427 \end{enumerate}
igor@402 428
igor@402 429 There's plenty of scope for confusion with the path component of ssh
igor@402 430 URLs, as there is no standard way for tools to interpret it. Some
igor@402 431 programs behave differently than others when dealing with these paths.
igor@402 432 This isn't an ideal situation, but it's unlikely to change. Please
igor@402 433 read the following paragraphs carefully.
igor@402 434
igor@402 435 Mercurial treats the path to a repository on the server as relative to
igor@402 436 the remote user's home directory. For example, if user \texttt{foo}
igor@402 437 on the server has a home directory of \dirname{/home/foo}, then an ssh
igor@402 438 URL that contains a path component of \dirname{bar}
igor@402 439 \emph{really} refers to the directory \dirname{/home/foo/bar}.
igor@402 440
igor@402 441 If you want to specify a path relative to another user's home
igor@402 442 directory, you can use a path that starts with a tilde character
igor@402 443 followed by the user's name (let's call them \texttt{otheruser}), like
igor@402 444 this.
igor@402 445 \begin{codesample2}
igor@402 446 ssh://server/~otheruser/hg/repo
igor@402 447 \end{codesample2}
igor@402 448
igor@402 449 And if you really want to specify an \emph{absolute} path on the
igor@402 450 server, begin the path component with two slashes, as in this example.
igor@402 451 \begin{codesample2}
igor@402 452 ssh://server//absolute/path
igor@402 453 \end{codesample2}
igor@402 454
igor@402 455 \subsection{Finding an ssh client for your system}
igor@402 456
igor@402 457 Almost every Unix-like system comes with OpenSSH preinstalled. If
igor@402 458 you're using such a system, run \Verb|which ssh| to find out if
igor@402 459 the \command{ssh} command is installed (it's usually in
igor@402 460 \dirname{/usr/bin}). In the unlikely event that it isn't present,
igor@402 461 take a look at your system documentation to figure out how to install
igor@402 462 it.
igor@402 463
igor@402 464 On Windows, you'll first need to choose download a suitable ssh
igor@402 465 client. There are two alternatives.
igor@402 466 \begin{itemize}
igor@402 467 \item Simon Tatham's excellent PuTTY package~\cite{web:putty} provides
igor@402 468 a complete suite of ssh client commands.
igor@402 469 \item If you have a high tolerance for pain, you can use the Cygwin
igor@402 470 port of OpenSSH.
igor@402 471 \end{itemize}
igor@402 472 In either case, you'll need to edit your \hgini\ file to tell
igor@402 473 Mercurial where to find the actual client command. For example, if
igor@402 474 you're using PuTTY, you'll need to use the \command{plink} command as
igor@402 475 a command-line ssh client.
igor@402 476 \begin{codesample2}
igor@402 477 [ui]
igor@402 478 ssh = C:/path/to/plink.exe -ssh -i "C:/path/to/my/private/key"
igor@402 479 \end{codesample2}
igor@402 480
igor@402 481 \begin{note}
igor@402 482 The path to \command{plink} shouldn't contain any whitespace
igor@402 483 characters, or Mercurial may not be able to run it correctly (so
igor@402 484 putting it in \dirname{C:\\Program Files} is probably not a good
igor@402 485 idea).
igor@402 486 \end{note}
igor@402 487
igor@402 488 \subsection{Generating a key pair}
igor@402 489
igor@402 490 To avoid the need to repetitively type a password every time you need
igor@402 491 to use your ssh client, I recommend generating a key pair. On a
igor@402 492 Unix-like system, the \command{ssh-keygen} command will do the trick.
igor@402 493 On Windows, if you're using PuTTY, the \command{puttygen} command is
igor@402 494 what you'll need.
igor@402 495
igor@402 496 When you generate a key pair, it's usually \emph{highly} advisable to
igor@402 497 protect it with a passphrase. (The only time that you might not want
igor@402 498 to do this id when you're using the ssh protocol for automated tasks
igor@402 499 on a secure network.)
igor@402 500
igor@402 501 Simply generating a key pair isn't enough, however. You'll need to
igor@402 502 add the public key to the set of authorised keys for whatever user
igor@402 503 you're logging in remotely as. For servers using OpenSSH (the vast
igor@402 504 majority), this will mean adding the public key to a list in a file
igor@402 505 called \sfilename{authorized\_keys} in their \sdirname{.ssh}
igor@402 506 directory.
igor@402 507
igor@402 508 On a Unix-like system, your public key will have a \filename{.pub}
igor@402 509 extension. If you're using \command{puttygen} on Windows, you can
igor@402 510 save the public key to a file of your choosing, or paste it from the
igor@402 511 window it's displayed in straight into the
igor@402 512 \sfilename{authorized\_keys} file.
igor@402 513
igor@402 514 \subsection{Using an authentication agent}
igor@402 515
igor@402 516 An authentication agent is a daemon that stores passphrases in memory
igor@402 517 (so it will forget passphrases if you log out and log back in again).
igor@402 518 An ssh client will notice if it's running, and query it for a
igor@402 519 passphrase. If there's no authentication agent running, or the agent
igor@402 520 doesn't store the necessary passphrase, you'll have to type your
igor@402 521 passphrase every time Mercurial tries to communicate with a server on
igor@402 522 your behalf (e.g.~whenever you pull or push changes).
igor@402 523
igor@402 524 The downside of storing passphrases in an agent is that it's possible
igor@402 525 for a well-prepared attacker to recover the plain text of your
igor@402 526 passphrases, in some cases even if your system has been power-cycled.
igor@402 527 You should make your own judgment as to whether this is an acceptable
igor@402 528 risk. It certainly saves a lot of repeated typing.
igor@402 529
igor@402 530 On Unix-like systems, the agent is called \command{ssh-agent}, and
igor@402 531 it's often run automatically for you when you log in. You'll need to
igor@402 532 use the \command{ssh-add} command to add passphrases to the agent's
igor@402 533 store. On Windows, if you're using PuTTY, the \command{pageant}
igor@402 534 command acts as the agent. It adds an icon to your system tray that
igor@402 535 will let you manage stored passphrases.
igor@402 536
igor@402 537 \subsection{Configuring the server side properly}
igor@402 538
igor@402 539 Because ssh can be fiddly to set up if you're new to it, there's a
igor@402 540 variety of things that can go wrong. Add Mercurial on top, and
igor@402 541 there's plenty more scope for head-scratching. Most of these
igor@402 542 potential problems occur on the server side, not the client side. The
igor@402 543 good news is that once you've gotten a configuration working, it will
igor@402 544 usually continue to work indefinitely.
igor@402 545
igor@402 546 Before you try using Mercurial to talk to an ssh server, it's best to
igor@402 547 make sure that you can use the normal \command{ssh} or \command{putty}
igor@402 548 command to talk to the server first. If you run into problems with
igor@402 549 using these commands directly, Mercurial surely won't work. Worse, it
igor@402 550 will obscure the underlying problem. Any time you want to debug
igor@402 551 ssh-related Mercurial problems, you should drop back to making sure
igor@402 552 that plain ssh client commands work first, \emph{before} you worry
igor@402 553 about whether there's a problem with Mercurial.
igor@402 554
igor@402 555 The first thing to be sure of on the server side is that you can
igor@402 556 actually log in from another machine at all. If you can't use
igor@402 557 \command{ssh} or \command{putty} to log in, the error message you get
igor@402 558 may give you a few hints as to what's wrong. The most common problems
igor@402 559 are as follows.
igor@402 560 \begin{itemize}
igor@402 561 \item If you get a ``connection refused'' error, either there isn't an
igor@402 562 SSH daemon running on the server at all, or it's inaccessible due to
igor@402 563 firewall configuration.
igor@402 564 \item If you get a ``no route to host'' error, you either have an
igor@402 565 incorrect address for the server or a seriously locked down firewall
igor@402 566 that won't admit its existence at all.
igor@402 567 \item If you get a ``permission denied'' error, you may have mistyped
igor@402 568 the username on the server, or you could have mistyped your key's
igor@402 569 passphrase or the remote user's password.
igor@402 570 \end{itemize}
igor@402 571 In summary, if you're having trouble talking to the server's ssh
igor@402 572 daemon, first make sure that one is running at all. On many systems
igor@402 573 it will be installed, but disabled, by default. Once you're done with
igor@402 574 this step, you should then check that the server's firewall is
igor@402 575 configured to allow incoming connections on the port the ssh daemon is
igor@402 576 listening on (usually~22). Don't worry about more exotic
igor@402 577 possibilities for misconfiguration until you've checked these two
igor@402 578 first.
igor@402 579
igor@402 580 If you're using an authentication agent on the client side to store
igor@402 581 passphrases for your keys, you ought to be able to log into the server
igor@402 582 without being prompted for a passphrase or a password. If you're
igor@402 583 prompted for a passphrase, there are a few possible culprits.
igor@402 584 \begin{itemize}
igor@402 585 \item You might have forgotten to use \command{ssh-add} or
igor@402 586 \command{pageant} to store the passphrase.
igor@402 587 \item You might have stored the passphrase for the wrong key.
igor@402 588 \end{itemize}
igor@402 589 If you're being prompted for the remote user's password, there are
igor@402 590 another few possible problems to check.
igor@402 591 \begin{itemize}
igor@402 592 \item Either the user's home directory or their \sdirname{.ssh}
igor@402 593 directory might have excessively liberal permissions. As a result,
igor@402 594 the ssh daemon will not trust or read their
igor@402 595 \sfilename{authorized\_keys} file. For example, a group-writable
igor@402 596 home or \sdirname{.ssh} directory will often cause this symptom.
igor@402 597 \item The user's \sfilename{authorized\_keys} file may have a problem.
igor@402 598 If anyone other than the user owns or can write to that file, the
igor@402 599 ssh daemon will not trust or read it.
igor@402 600 \end{itemize}
igor@402 601
igor@402 602 In the ideal world, you should be able to run the following command
igor@402 603 successfully, and it should print exactly one line of output, the
igor@402 604 current date and time.
igor@402 605 \begin{codesample2}
igor@402 606 ssh myserver date
igor@402 607 \end{codesample2}
igor@402 608
igor@402 609 If, on your server, you have login scripts that print banners or other
igor@402 610 junk even when running non-interactive commands like this, you should
igor@402 611 fix them before you continue, so that they only print output if
igor@402 612 they're run interactively. Otherwise these banners will at least
igor@402 613 clutter up Mercurial's output. Worse, they could potentially cause
igor@402 614 problems with running Mercurial commands remotely. Mercurial makes
igor@402 615 tries to detect and ignore banners in non-interactive \command{ssh}
igor@402 616 sessions, but it is not foolproof. (If you're editing your login
igor@402 617 scripts on your server, the usual way to see if a login script is
igor@402 618 running in an interactive shell is to check the return code from the
igor@402 619 command \Verb|tty -s|.)
igor@402 620
igor@402 621 Once you've verified that plain old ssh is working with your server,
igor@402 622 the next step is to ensure that Mercurial runs on the server. The
igor@402 623 following command should run successfully:
igor@402 624 \begin{codesample2}
igor@402 625 ssh myserver hg version
igor@402 626 \end{codesample2}
igor@402 627 If you see an error message instead of normal \hgcmd{version} output,
igor@402 628 this is usually because you haven't installed Mercurial to
igor@402 629 \dirname{/usr/bin}. Don't worry if this is the case; you don't need
igor@402 630 to do that. But you should check for a few possible problems.
igor@402 631 \begin{itemize}
igor@402 632 \item Is Mercurial really installed on the server at all? I know this
igor@402 633 sounds trivial, but it's worth checking!
igor@402 634 \item Maybe your shell's search path (usually set via the \envar{PATH}
igor@402 635 environment variable) is simply misconfigured.
igor@402 636 \item Perhaps your \envar{PATH} environment variable is only being set
igor@402 637 to point to the location of the \command{hg} executable if the login
igor@402 638 session is interactive. This can happen if you're setting the path
igor@402 639 in the wrong shell login script. See your shell's documentation for
igor@402 640 details.
igor@402 641 \item The \envar{PYTHONPATH} environment variable may need to contain
igor@402 642 the path to the Mercurial Python modules. It might not be set at
igor@402 643 all; it could be incorrect; or it may be set only if the login is
igor@402 644 interactive.
igor@402 645 \end{itemize}
igor@402 646
igor@402 647 If you can run \hgcmd{version} over an ssh connection, well done!
igor@402 648 You've got the server and client sorted out. You should now be able
igor@402 649 to use Mercurial to access repositories hosted by that username on
igor@402 650 that server. If you run into problems with Mercurial and ssh at this
igor@402 651 point, try using the \hggopt{--debug} option to get a clearer picture
igor@402 652 of what's going on.
igor@402 653
igor@402 654 \subsection{Using compression with ssh}
igor@402 655
igor@402 656 Mercurial does not compress data when it uses the ssh protocol,
igor@402 657 because the ssh protocol can transparently compress data. However,
igor@402 658 the default behaviour of ssh clients is \emph{not} to request
igor@402 659 compression.
igor@402 660
igor@402 661 Over any network other than a fast LAN (even a wireless network),
igor@402 662 using compression is likely to significantly speed up Mercurial's
igor@402 663 network operations. For example, over a WAN, someone measured
igor@402 664 compression as reducing the amount of time required to clone a
igor@402 665 particularly large repository from~51 minutes to~17 minutes.
igor@402 666
igor@402 667 Both \command{ssh} and \command{plink} accept a \cmdopt{ssh}{-C}
igor@402 668 option which turns on compression. You can easily edit your \hgrc\ to
igor@402 669 enable compression for all of Mercurial's uses of the ssh protocol.
igor@402 670 \begin{codesample2}
igor@402 671 [ui]
igor@402 672 ssh = ssh -C
igor@402 673 \end{codesample2}
igor@402 674
igor@402 675 If you use \command{ssh}, you can configure it to always use
igor@402 676 compression when talking to your server. To do this, edit your
igor@402 677 \sfilename{.ssh/config} file (which may not yet exist), as follows.
igor@402 678 \begin{codesample2}
igor@402 679 Host hg
igor@402 680 Compression yes
igor@402 681 HostName hg.example.com
igor@402 682 \end{codesample2}
igor@402 683 This defines an alias, \texttt{hg}. When you use it on the
igor@402 684 \command{ssh} command line or in a Mercurial \texttt{ssh}-protocol
igor@402 685 URL, it will cause \command{ssh} to connect to \texttt{hg.example.com}
igor@402 686 and use compression. This gives you both a shorter name to type and
igor@402 687 compression, each of which is a good thing in its own right.
igor@402 688
igor@402 689 \section{Serving over HTTP using CGI}
igor@402 690 \label{sec:collab:cgi}
igor@402 691
igor@402 692 Depending on how ambitious you are, configuring Mercurial's CGI
igor@402 693 interface can take anything from a few moments to several hours.
igor@402 694
igor@402 695 We'll begin with the simplest of examples, and work our way towards a
igor@402 696 more complex configuration. Even for the most basic case, you're
igor@402 697 almost certainly going to need to read and modify your web server's
igor@402 698 configuration.
igor@402 699
igor@402 700 \begin{note}
igor@402 701 Configuring a web server is a complex, fiddly, and highly
igor@402 702 system-dependent activity. I can't possibly give you instructions
igor@402 703 that will cover anything like all of the cases you will encounter.
igor@402 704 Please use your discretion and judgment in following the sections
igor@402 705 below. Be prepared to make plenty of mistakes, and to spend a lot
igor@402 706 of time reading your server's error logs.
igor@402 707 \end{note}
igor@402 708
igor@402 709 \subsection{Web server configuration checklist}
igor@402 710
igor@402 711 Before you continue, do take a few moments to check a few aspects of
igor@402 712 your system's setup.
igor@402 713
igor@402 714 \begin{enumerate}
igor@402 715 \item Do you have a web server installed at all? Mac OS X ships with
igor@402 716 Apache, but many other systems may not have a web server installed.
igor@402 717 \item If you have a web server installed, is it actually running? On
igor@402 718 most systems, even if one is present, it will be disabled by
igor@402 719 default.
igor@402 720 \item Is your server configured to allow you to run CGI programs in
igor@402 721 the directory where you plan to do so? Most servers default to
igor@402 722 explicitly disabling the ability to run CGI programs.
igor@402 723 \end{enumerate}
igor@402 724
igor@402 725 If you don't have a web server installed, and don't have substantial
igor@402 726 experience configuring Apache, you should consider using the
igor@402 727 \texttt{lighttpd} web server instead of Apache. Apache has a
igor@402 728 well-deserved reputation for baroque and confusing configuration.
igor@402 729 While \texttt{lighttpd} is less capable in some ways than Apache, most
igor@402 730 of these capabilities are not relevant to serving Mercurial
igor@402 731 repositories. And \texttt{lighttpd} is undeniably \emph{much} easier
igor@402 732 to get started with than Apache.
igor@402 733
igor@402 734 \subsection{Basic CGI configuration}
igor@402 735
igor@402 736 On Unix-like systems, it's common for users to have a subdirectory
igor@402 737 named something like \dirname{public\_html} in their home directory,
igor@402 738 from which they can serve up web pages. A file named \filename{foo}
igor@402 739 in this directory will be accessible at a URL of the form
igor@402 740 \texttt{http://www.example.com/\~username/foo}.
igor@402 741
igor@402 742 To get started, find the \sfilename{hgweb.cgi} script that should be
igor@402 743 present in your Mercurial installation. If you can't quickly find a
igor@402 744 local copy on your system, simply download one from the master
igor@402 745 Mercurial repository at
igor@402 746 \url{http://www.selenic.com/repo/hg/raw-file/tip/hgweb.cgi}.
igor@402 747
igor@402 748 You'll need to copy this script into your \dirname{public\_html}
igor@402 749 directory, and ensure that it's executable.
igor@402 750 \begin{codesample2}
igor@402 751 cp .../hgweb.cgi ~/public_html
igor@402 752 chmod 755 ~/public_html/hgweb.cgi
igor@402 753 \end{codesample2}
igor@402 754 The \texttt{755} argument to \command{chmod} is a little more general
igor@402 755 than just making the script executable: it ensures that the script is
igor@402 756 executable by anyone, and that ``group'' and ``other'' write
igor@402 757 permissions are \emph{not} set. If you were to leave those write
igor@402 758 permissions enabled, Apache's \texttt{suexec} subsystem would likely
igor@402 759 refuse to execute the script. In fact, \texttt{suexec} also insists
igor@402 760 that the \emph{directory} in which the script resides must not be
igor@402 761 writable by others.
igor@402 762 \begin{codesample2}
igor@402 763 chmod 755 ~/public_html
igor@402 764 \end{codesample2}
igor@402 765
igor@402 766 \subsubsection{What could \emph{possibly} go wrong?}
igor@402 767 \label{sec:collab:wtf}
igor@402 768
igor@402 769 Once you've copied the CGI script into place, go into a web browser,
igor@402 770 and try to open the URL \url{http://myhostname/~myuser/hgweb.cgi},
igor@402 771 \emph{but} brace yourself for instant failure. There's a high
igor@402 772 probability that trying to visit this URL will fail, and there are
igor@402 773 many possible reasons for this. In fact, you're likely to stumble
igor@402 774 over almost every one of the possible errors below, so please read
igor@402 775 carefully. The following are all of the problems I ran into on a
igor@402 776 system running Fedora~7, with a fresh installation of Apache, and a
igor@402 777 user account that I created specially to perform this exercise.
igor@402 778
igor@402 779 Your web server may have per-user directories disabled. If you're
igor@402 780 using Apache, search your config file for a \texttt{UserDir}
igor@402 781 directive. If there's none present, per-user directories will be
igor@402 782 disabled. If one exists, but its value is \texttt{disabled}, then
igor@402 783 per-user directories will be disabled. Otherwise, the string after
igor@402 784 \texttt{UserDir} gives the name of the subdirectory that Apache will
igor@402 785 look in under your home directory, for example \dirname{public\_html}.
igor@402 786
igor@402 787 Your file access permissions may be too restrictive. The web server
igor@402 788 must be able to traverse your home directory and directories under
igor@402 789 your \dirname{public\_html} directory, and read files under the latter
igor@402 790 too. Here's a quick recipe to help you to make your permissions more
igor@402 791 appropriate.
igor@402 792 \begin{codesample2}
igor@402 793 chmod 755 ~
igor@402 794 find ~/public_html -type d -print0 | xargs -0r chmod 755
igor@402 795 find ~/public_html -type f -print0 | xargs -0r chmod 644
igor@402 796 \end{codesample2}
igor@402 797
igor@402 798 The other possibility with permissions is that you might get a
igor@402 799 completely empty window when you try to load the script. In this
igor@402 800 case, it's likely that your access permissions are \emph{too
igor@402 801 permissive}. Apache's \texttt{suexec} subsystem won't execute a
igor@402 802 script that's group-~or world-writable, for example.
igor@402 803
igor@402 804 Your web server may be configured to disallow execution of CGI
igor@402 805 programs in your per-user web directory. Here's Apache's
igor@402 806 default per-user configuration from my Fedora system.
igor@402 807 \begin{codesample2}
igor@402 808 <Directory /home/*/public_html>
igor@402 809 AllowOverride FileInfo AuthConfig Limit
igor@402 810 Options MultiViews Indexes SymLinksIfOwnerMatch IncludesNoExec
igor@402 811 <Limit GET POST OPTIONS>
igor@402 812 Order allow,deny
igor@402 813 Allow from all
igor@402 814 </Limit>
igor@402 815 <LimitExcept GET POST OPTIONS>
igor@402 816 Order deny,allow
igor@402 817 Deny from all
igor@402 818 </LimitExcept>
igor@402 819 </Directory>
igor@402 820 \end{codesample2}
igor@402 821 If you find a similar-looking \texttt{Directory} group in your Apache
igor@402 822 configuration, the directive to look at inside it is \texttt{Options}.
igor@402 823 Add \texttt{ExecCGI} to the end of this list if it's missing, and
igor@402 824 restart the web server.
igor@402 825
igor@402 826 If you find that Apache serves you the text of the CGI script instead
igor@402 827 of executing it, you may need to either uncomment (if already present)
igor@402 828 or add a directive like this.
igor@402 829 \begin{codesample2}
igor@402 830 AddHandler cgi-script .cgi
igor@402 831 \end{codesample2}
igor@402 832
igor@402 833 The next possibility is that you might be served with a colourful
igor@402 834 Python backtrace claiming that it can't import a
igor@402 835 \texttt{mercurial}-related module. This is actually progress! The
igor@402 836 server is now capable of executing your CGI script. This error is
igor@402 837 only likely to occur if you're running a private installation of
igor@402 838 Mercurial, instead of a system-wide version. Remember that the web
igor@402 839 server runs the CGI program without any of the environment variables
igor@402 840 that you take for granted in an interactive session. If this error
igor@402 841 happens to you, edit your copy of \sfilename{hgweb.cgi} and follow the
igor@402 842 directions inside it to correctly set your \envar{PYTHONPATH}
igor@402 843 environment variable.
igor@402 844
igor@402 845 Finally, you are \emph{certain} to by served with another colourful
igor@402 846 Python backtrace: this one will complain that it can't find
igor@402 847 \dirname{/path/to/repository}. Edit your \sfilename{hgweb.cgi} script
igor@402 848 and replace the \dirname{/path/to/repository} string with the complete
igor@402 849 path to the repository you want to serve up.
igor@402 850
igor@402 851 At this point, when you try to reload the page, you should be
igor@402 852 presented with a nice HTML view of your repository's history. Whew!
igor@402 853
igor@402 854 \subsubsection{Configuring lighttpd}
igor@402 855
igor@402 856 To be exhaustive in my experiments, I tried configuring the
igor@402 857 increasingly popular \texttt{lighttpd} web server to serve the same
igor@402 858 repository as I described with Apache above. I had already overcome
igor@402 859 all of the problems I outlined with Apache, many of which are not
igor@402 860 server-specific. As a result, I was fairly sure that my file and
igor@402 861 directory permissions were good, and that my \sfilename{hgweb.cgi}
igor@402 862 script was properly edited.
igor@402 863
igor@402 864 Once I had Apache running, getting \texttt{lighttpd} to serve the
igor@402 865 repository was a snap (in other words, even if you're trying to use
igor@402 866 \texttt{lighttpd}, you should read the Apache section). I first had
igor@402 867 to edit the \texttt{mod\_access} section of its config file to enable
igor@402 868 \texttt{mod\_cgi} and \texttt{mod\_userdir}, both of which were
igor@402 869 disabled by default on my system. I then added a few lines to the end
igor@402 870 of the config file, to configure these modules.
igor@402 871 \begin{codesample2}
igor@402 872 userdir.path = "public_html"
igor@402 873 cgi.assign = ( ".cgi" => "" )
igor@402 874 \end{codesample2}
igor@402 875 With this done, \texttt{lighttpd} ran immediately for me. If I had
igor@402 876 configured \texttt{lighttpd} before Apache, I'd almost certainly have
igor@402 877 run into many of the same system-level configuration problems as I did
igor@402 878 with Apache. However, I found \texttt{lighttpd} to be noticeably
igor@402 879 easier to configure than Apache, even though I've used Apache for over
igor@402 880 a decade, and this was my first exposure to \texttt{lighttpd}.
igor@402 881
igor@402 882 \subsection{Sharing multiple repositories with one CGI script}
igor@402 883
igor@402 884 The \sfilename{hgweb.cgi} script only lets you publish a single
igor@402 885 repository, which is an annoying restriction. If you want to publish
igor@402 886 more than one without wracking yourself with multiple copies of the
igor@402 887 same script, each with different names, a better choice is to use the
igor@402 888 \sfilename{hgwebdir.cgi} script.
igor@402 889
igor@402 890 The procedure to configure \sfilename{hgwebdir.cgi} is only a little
igor@402 891 more involved than for \sfilename{hgweb.cgi}. First, you must obtain
igor@402 892 a copy of the script. If you don't have one handy, you can download a
igor@402 893 copy from the master Mercurial repository at
igor@402 894 \url{http://www.selenic.com/repo/hg/raw-file/tip/hgwebdir.cgi}.
igor@402 895
igor@402 896 You'll need to copy this script into your \dirname{public\_html}
igor@402 897 directory, and ensure that it's executable.
igor@402 898 \begin{codesample2}
igor@402 899 cp .../hgwebdir.cgi ~/public_html
igor@402 900 chmod 755 ~/public_html ~/public_html/hgwebdir.cgi
igor@402 901 \end{codesample2}
igor@402 902 With basic configuration out of the way, try to visit
igor@402 903 \url{http://myhostname/~myuser/hgwebdir.cgi} in your browser. It
igor@402 904 should display an empty list of repositories. If you get a blank
igor@402 905 window or error message, try walking through the list of potential
igor@402 906 problems in section~\ref{sec:collab:wtf}.
igor@402 907
igor@402 908 The \sfilename{hgwebdir.cgi} script relies on an external
igor@402 909 configuration file. By default, it searches for a file named
igor@402 910 \sfilename{hgweb.config} in the same directory as itself. You'll need
igor@402 911 to create this file, and make it world-readable. The format of the
igor@402 912 file is similar to a Windows ``ini'' file, as understood by Python's
igor@402 913 \texttt{ConfigParser}~\cite{web:configparser} module.
igor@402 914
igor@402 915 The easiest way to configure \sfilename{hgwebdir.cgi} is with a
igor@402 916 section named \texttt{collections}. This will automatically publish
igor@402 917 \emph{every} repository under the directories you name. The section
igor@402 918 should look like this:
igor@402 919 \begin{codesample2}
igor@402 920 [collections]
igor@402 921 /my/root = /my/root
igor@402 922 \end{codesample2}
igor@402 923 Mercurial interprets this by looking at the directory name on the
igor@402 924 \emph{right} hand side of the ``\texttt{=}'' sign; finding
igor@402 925 repositories in that directory hierarchy; and using the text on the
igor@402 926 \emph{left} to strip off matching text from the names it will actually
igor@402 927 list in the web interface. The remaining component of a path after
igor@402 928 this stripping has occurred is called a ``virtual path''.
igor@402 929
igor@402 930 Given the example above, if we have a repository whose local path is
igor@402 931 \dirname{/my/root/this/repo}, the CGI script will strip the leading
igor@402 932 \dirname{/my/root} from the name, and publish the repository with a
igor@402 933 virtual path of \dirname{this/repo}. If the base URL for our CGI
igor@402 934 script is \url{http://myhostname/~myuser/hgwebdir.cgi}, the complete
igor@402 935 URL for that repository will be
igor@402 936 \url{http://myhostname/~myuser/hgwebdir.cgi/this/repo}.
igor@402 937
igor@402 938 If we replace \dirname{/my/root} on the left hand side of this example
igor@402 939 with \dirname{/my}, then \sfilename{hgwebdir.cgi} will only strip off
igor@402 940 \dirname{/my} from the repository name, and will give us a virtual
igor@402 941 path of \dirname{root/this/repo} instead of \dirname{this/repo}.
igor@402 942
igor@402 943 The \sfilename{hgwebdir.cgi} script will recursively search each
igor@402 944 directory listed in the \texttt{collections} section of its
igor@402 945 configuration file, but it will \texttt{not} recurse into the
igor@402 946 repositories it finds.
igor@402 947
igor@402 948 The \texttt{collections} mechanism makes it easy to publish many
igor@402 949 repositories in a ``fire and forget'' manner. You only need to set up
igor@402 950 the CGI script and configuration file one time. Afterwards, you can
igor@402 951 publish or unpublish a repository at any time by simply moving it
igor@402 952 into, or out of, the directory hierarchy in which you've configured
igor@402 953 \sfilename{hgwebdir.cgi} to look.
igor@402 954
igor@402 955 \subsubsection{Explicitly specifying which repositories to publish}
igor@402 956
igor@402 957 In addition to the \texttt{collections} mechanism, the
igor@402 958 \sfilename{hgwebdir.cgi} script allows you to publish a specific list
igor@402 959 of repositories. To do so, create a \texttt{paths} section, with
igor@402 960 contents of the following form.
igor@402 961 \begin{codesample2}
igor@402 962 [paths]
igor@402 963 repo1 = /my/path/to/some/repo
igor@402 964 repo2 = /some/path/to/another
igor@402 965 \end{codesample2}
igor@402 966 In this case, the virtual path (the component that will appear in a
igor@402 967 URL) is on the left hand side of each definition, while the path to
igor@402 968 the repository is on the right. Notice that there does not need to be
igor@402 969 any relationship between the virtual path you choose and the location
igor@402 970 of a repository in your filesystem.
igor@402 971
igor@402 972 If you wish, you can use both the \texttt{collections} and
igor@402 973 \texttt{paths} mechanisms simultaneously in a single configuration
igor@402 974 file.
igor@402 975
igor@402 976 \begin{note}
igor@402 977 If multiple repositories have the same virtual path,
igor@402 978 \sfilename{hgwebdir.cgi} will not report an error. Instead, it will
igor@402 979 behave unpredictably.
igor@402 980 \end{note}
igor@402 981
igor@402 982 \subsection{Downloading source archives}
igor@402 983
igor@402 984 Mercurial's web interface lets users download an archive of any
igor@402 985 revision. This archive will contain a snapshot of the working
igor@402 986 directory as of that revision, but it will not contain a copy of the
igor@402 987 repository data.
igor@402 988
igor@402 989 By default, this feature is not enabled. To enable it, you'll need to
igor@402 990 add an \rcitem{web}{allow\_archive} item to the \rcsection{web}
igor@402 991 section of your \hgrc.
igor@402 992
igor@402 993 \subsection{Web configuration options}
igor@402 994
igor@402 995 Mercurial's web interfaces (the \hgcmd{serve} command, and the
igor@402 996 \sfilename{hgweb.cgi} and \sfilename{hgwebdir.cgi} scripts) have a
igor@402 997 number of configuration options that you can set. These belong in a
igor@402 998 section named \rcsection{web}.
igor@402 999 \begin{itemize}
igor@402 1000 \item[\rcitem{web}{allow\_archive}] Determines which (if any) archive
igor@402 1001 download mechanisms Mercurial supports. If you enable this
igor@402 1002 feature, users of the web interface will be able to download an
igor@402 1003 archive of whatever revision of a repository they are viewing.
igor@402 1004 To enable the archive feature, this item must take the form of a
igor@402 1005 sequence of words drawn from the list below.
igor@402 1006 \begin{itemize}
igor@402 1007 \item[\texttt{bz2}] A \command{tar} archive, compressed using
igor@402 1008 \texttt{bzip2} compression. This has the best compression ratio,
igor@402 1009 but uses the most CPU time on the server.
igor@402 1010 \item[\texttt{gz}] A \command{tar} archive, compressed using
igor@402 1011 \texttt{gzip} compression.
igor@402 1012 \item[\texttt{zip}] A \command{zip} archive, compressed using LZW
igor@402 1013 compression. This format has the worst compression ratio, but is
igor@402 1014 widely used in the Windows world.
igor@402 1015 \end{itemize}
igor@402 1016 If you provide an empty list, or don't have an
igor@402 1017 \rcitem{web}{allow\_archive} entry at all, this feature will be
igor@402 1018 disabled. Here is an example of how to enable all three supported
igor@402 1019 formats.
igor@402 1020 \begin{codesample4}
igor@402 1021 [web]
igor@402 1022 allow_archive = bz2 gz zip
igor@402 1023 \end{codesample4}
igor@402 1024 \item[\rcitem{web}{allowpull}] Boolean. Determines whether the web
igor@402 1025 interface allows remote users to \hgcmd{pull} and \hgcmd{clone} this
igor@402 1026 repository over~HTTP. If set to \texttt{no} or \texttt{false}, only
igor@402 1027 the ``human-oriented'' portion of the web interface is available.
igor@402 1028 \item[\rcitem{web}{contact}] String. A free-form (but preferably
igor@402 1029 brief) string identifying the person or group in charge of the
igor@402 1030 repository. This often contains the name and email address of a
igor@402 1031 person or mailing list. It often makes sense to place this entry in
igor@402 1032 a repository's own \sfilename{.hg/hgrc} file, but it can make sense
igor@402 1033 to use in a global \hgrc\ if every repository has a single
igor@402 1034 maintainer.
igor@402 1035 \item[\rcitem{web}{maxchanges}] Integer. The default maximum number
igor@402 1036 of changesets to display in a single page of output.
igor@402 1037 \item[\rcitem{web}{maxfiles}] Integer. The default maximum number
igor@402 1038 of modified files to display in a single page of output.
igor@402 1039 \item[\rcitem{web}{stripes}] Integer. If the web interface displays
igor@402 1040 alternating ``stripes'' to make it easier to visually align rows
igor@402 1041 when you are looking at a table, this number controls the number of
igor@402 1042 rows in each stripe.
igor@402 1043 \item[\rcitem{web}{style}] Controls the template Mercurial uses to
igor@402 1044 display the web interface. Mercurial ships with two web templates,
igor@402 1045 named \texttt{default} and \texttt{gitweb} (the latter is much more
igor@402 1046 visually attractive). You can also specify a custom template of
igor@402 1047 your own; see chapter~\ref{chap:template} for details. Here, you
igor@402 1048 can see how to enable the \texttt{gitweb} style.
igor@402 1049 \begin{codesample4}
igor@402 1050 [web]
igor@402 1051 style = gitweb
igor@402 1052 \end{codesample4}
igor@402 1053 \item[\rcitem{web}{templates}] Path. The directory in which to search
igor@402 1054 for template files. By default, Mercurial searches in the directory
igor@402 1055 in which it was installed.
igor@402 1056 \end{itemize}
igor@402 1057 If you are using \sfilename{hgwebdir.cgi}, you can place a few
igor@402 1058 configuration items in a \rcsection{web} section of the
igor@402 1059 \sfilename{hgweb.config} file instead of a \hgrc\ file, for
igor@402 1060 convenience. These items are \rcitem{web}{motd} and
igor@402 1061 \rcitem{web}{style}.
igor@402 1062
igor@402 1063 \subsubsection{Options specific to an individual repository}
igor@402 1064
igor@402 1065 A few \rcsection{web} configuration items ought to be placed in a
igor@402 1066 repository's local \sfilename{.hg/hgrc}, rather than a user's or
igor@402 1067 global \hgrc.
igor@402 1068 \begin{itemize}
igor@402 1069 \item[\rcitem{web}{description}] String. A free-form (but preferably
igor@402 1070 brief) string that describes the contents or purpose of the
igor@402 1071 repository.
igor@402 1072 \item[\rcitem{web}{name}] String. The name to use for the repository
igor@402 1073 in the web interface. This overrides the default name, which is the
igor@402 1074 last component of the repository's path.
igor@402 1075 \end{itemize}
igor@402 1076
igor@402 1077 \subsubsection{Options specific to the \hgcmd{serve} command}
igor@402 1078
igor@402 1079 Some of the items in the \rcsection{web} section of a \hgrc\ file are
igor@402 1080 only for use with the \hgcmd{serve} command.
igor@402 1081 \begin{itemize}
igor@402 1082 \item[\rcitem{web}{accesslog}] Path. The name of a file into which to
igor@402 1083 write an access log. By default, the \hgcmd{serve} command writes
igor@402 1084 this information to standard output, not to a file. Log entries are
igor@402 1085 written in the standard ``combined'' file format used by almost all
igor@402 1086 web servers.
igor@402 1087 \item[\rcitem{web}{address}] String. The local address on which the
igor@402 1088 server should listen for incoming connections. By default, the
igor@402 1089 server listens on all addresses.
igor@402 1090 \item[\rcitem{web}{errorlog}] Path. The name of a file into which to
igor@402 1091 write an error log. By default, the \hgcmd{serve} command writes this
igor@402 1092 information to standard error, not to a file.
igor@402 1093 \item[\rcitem{web}{ipv6}] Boolean. Whether to use the IPv6 protocol.
igor@402 1094 By default, IPv6 is not used.
igor@402 1095 \item[\rcitem{web}{port}] Integer. The TCP~port number on which the
igor@402 1096 server should listen. The default port number used is~8000.
igor@402 1097 \end{itemize}
igor@402 1098
igor@402 1099 \subsubsection{Choosing the right \hgrc\ file to add \rcsection{web}
igor@402 1100 items to}
igor@402 1101
igor@402 1102 It is important to remember that a web server like Apache or
igor@402 1103 \texttt{lighttpd} will run under a user~ID that is different to yours.
igor@402 1104 CGI scripts run by your server, such as \sfilename{hgweb.cgi}, will
igor@402 1105 usually also run under that user~ID.
igor@402 1106
igor@402 1107 If you add \rcsection{web} items to your own personal \hgrc\ file, CGI
igor@402 1108 scripts won't read that \hgrc\ file. Those settings will thus only
igor@402 1109 affect the behaviour of the \hgcmd{serve} command when you run it. To
igor@402 1110 cause CGI scripts to see your settings, either create a \hgrc\ file in
igor@402 1111 the home directory of the user ID that runs your web server, or add
igor@402 1112 those settings to a system-wide \hgrc\ file.
igor@402 1113
igor@402 1114
igor@402 1115 %%% Local Variables:
igor@402 1116 %%% mode: latex
igor@402 1117 %%% TeX-master: "00book"
igor@402 1118 %%% End: