diff options
| author | Owen Jacobson <owen.jacobson@grimoire.ca> | 2015-07-03 22:31:49 -0400 |
|---|---|---|
| committer | Owen Jacobson <owen.jacobson@grimoire.ca> | 2015-07-03 22:35:09 -0400 |
| commit | 76aed6ef732de38d82245b3d674f70bab30221e5 (patch) | |
| tree | d50e9a296d91ef8a49bcb29c3e80096f200a3c26 /.html/git/stop-using-git-pull-to-deploy.html | |
| parent | 92f66d3e3a0996bb1fad9dc83d7e184f92673e5d (diff) | |
Fuck it, serve the files directly.
Diffstat (limited to '.html/git/stop-using-git-pull-to-deploy.html')
| -rw-r--r-- | .html/git/stop-using-git-pull-to-deploy.html | 178 |
1 files changed, 178 insertions, 0 deletions
diff --git a/.html/git/stop-using-git-pull-to-deploy.html b/.html/git/stop-using-git-pull-to-deploy.html new file mode 100644 index 0000000..a3736a0 --- /dev/null +++ b/.html/git/stop-using-git-pull-to-deploy.html @@ -0,0 +1,178 @@ +<!DOCTYPE html> +<html> +<head> + <title> + The Codex » + Stop Using Git Pull To Deploy + </title> + + <link + rel='stylesheet' + type='text/css' + href='http://fonts.googleapis.com/css?family=Buenard:400,700&subset=latin,latin-ext'> + <link + rel="stylesheet" + type="text/css" + href="../media/css/reset.css"> + <link + rel="stylesheet" + type="text/css" + href="../media/css/grimoire.css"> +</head> +<body> + +<div id="shell"> + + <ol id="breadcrumbs"> + + <li class="crumb-0 not-last"> + + <a href="../">index</a> + + </li> + + <li class="crumb-1 not-last"> + + <a href="./">git</a> + + </li> + + <li class="crumb-2 last"> + + stop-using-git-pull-to-deploy + + </li> + + </ol> + + + + <div id="article"> + <h1 id="stop-using-git-pull-for-deployment">Stop using <code>git pull</code> for deployment!</h1> +<h2 id="the-problem">The problem</h2> +<ul> +<li>You have a Git repository containing your project.</li> +<li>You want to “deploy” that code when it changes.</li> +<li>You'd rather not download the entire project from scratch for each + deployment.</li> +</ul> +<h2 id="the-antipattern">The antipattern</h2> +<p>“I know, I'll use <code>git pull</code> in my deployment script!”</p> +<p>Stop doing this. Stop teaching other people to do this. It's wrong, and it +will eventually lead to deploying something you didn't want.</p> +<p>Deployment should be based on predictable, known versions of your code. +Ideally, every deployable version has a tag (and you deploy exactly that tag), +but even less formal processes, where you deploy a branch tip, should still be +deploying exactly the code designated for release. <code>git pull</code>, however, can +introduce new commits.</p> +<p><code>git pull</code> is a two-step process:</p> +<ol> +<li>Fetch the current branch's designated upstream remote, to obtain all of the + remote's new commits.</li> +<li>Merge the current branch's designated upstream branch into the current + branch.</li> +</ol> +<p>The merge commit means the actual deployed tree might <em>not</em> be identical to +the intended deployment tree. Local changes (intentional or otherwise) will be +preserved (and merged) into the deployment, for example; once this happens, +the actual deployed commit will <em>never</em> match the intended commit.</p> +<p><code>git pull</code> will approximate the right thing “by accident”: if the current +local branch (generally <code>master</code>) for people using <code>git pull</code> is always clean, +and always tracks the desired deployment branch, then <code>git pull</code> will update +to the intended commit exactly. This is pretty fragile, though; many git +commands can cause the local branch to diverge from its upstream branch, and +once that happens, <code>git pull</code> will always create new commits. You can patch +around the fragility a bit using the <code>--ff-only</code> option, but that only tells +you when your deployment environment has diverged and doesn't fix it.</p> +<h2 id="the-right-pattern">The right pattern</h2> +<p>Quoting <a href="http://gitolite.com/the-list-and-irc/deploy.html">Sitaram Chamarty</a>:</p> +<blockquote> +<p>Here's what we expect from a deployment tool. Note the rule numbers -- +we'll be referring to some of them simply by number later.</p> +<ol> +<li> +<p>All files in the branch being deployed should be copied to the + deployment directory.</p> +</li> +<li> +<p>Files that were deleted in the git repo since the last deployment + should get deleted from the deployment directory.</p> +</li> +<li> +<p>Any changes to tracked files in the deployment directory after the + last deployment should be ignored when following rules 1 and 2.</p> +<p>However, sometimes you might want to detect such changes and abort if +you found any.</p> +</li> +<li> +<p>Untracked files in the deploy directory should be left alone.</p> +<p>Again, some people might want to detect this and abort the deployment.</p> +</li> +</ol> +</blockquote> +<p>Sitaram's own documentation talks about how to accomplish these when +“deploying” straight out of a bare repository. That's unwise (not to mention +impractical) in most cases; deployment should use a dedicated clone of the +canonical repository.</p> +<p>I also disagree with point 3, preferring to keep deployment-related changes +outside of tracked files. This makes it much easier to argue that the changes +introduced to configure the project for deployment do not introduce new bugs +or other surprise features.</p> +<p>My deployment process, given a dedicated clone at <code>$DEPLOY_TREE</code>, is as +follows:</p> +<pre><code>cd "${DEPLOY_TREE}" +git fetch --all +git checkout --force "${TARGET}" +# Following two lines only required if you use submodules +git submodule sync +git submodule update --init --recursive +# Follow with actual deployment steps (run fabric/capistrano/make/etc) +</code></pre> +<p><code>$TARGET</code> is either a tag name (<code>v1.2.1</code>) or a remote branch name +(<code>origin/master</code>), but could also be a commit hash or anything else Git +recognizes as a revision. This will detach the head of the <code>$DEPLOY_TREE</code> +repository, which is fine as no new changes should be authored in this +repository (so the local branches are irrelevant). The warning Git emits when +<code>HEAD</code> becomes detached is unimportant in this case.</p> +<p>The tracked contents of <code>$DEPLOY_TREE</code> will end up identical to the desired +commit, discarding local changes. The pattern above is very similar to what +most continuous integration servers use when building from Git repositories, +for much the same reason.</p> + </div> + + + +<div id="comments"> +<div id="disqus_thread"></div> +<script type="text/javascript"> + /* * * CONFIGURATION VARIABLES: EDIT BEFORE PASTING INTO YOUR WEBPAGE * * */ + var disqus_shortname = 'grimoire'; // required: replace example with your forum shortname + + /* * * DON'T EDIT BELOW THIS LINE * * */ + (function() { + var dsq = document.createElement('script'); dsq.type = 'text/javascript'; dsq.async = true; + dsq.src = 'http://' + disqus_shortname + '.disqus.com/embed.js'; + (document.getElementsByTagName('head')[0] || document.getElementsByTagName('body')[0]).appendChild(dsq); + })(); +</script> +<noscript>Please enable JavaScript to view the <a href="http://disqus.com/?ref_noscript">comments powered by Disqus.</a></noscript> +<a href="http://disqus.com" class="dsq-brlink">comments powered by <span class="logo-disqus">Disqus</span></a> +</div> + + + + <div id="footer"> + <p> + + The Codex — + + Powered by <a href="http://markdoc.org/">Markdoc</a>. + +<a href="https://bitbucket.org/ojacobson/grimoire.ca/src/master/wiki/git/stop-using-git-pull-to-deploy.md">See this page on Bitbucket</a> (<a href="https://bitbucket.org/ojacobson/grimoire.ca/history-node/master/wiki/git/stop-using-git-pull-to-deploy.md">history</a>). + + </p> + </div> + +</div> +</body> +</html>
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