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authorTom Willemse2016-02-21 15:52:51 +0100
committerTom Willemse2016-02-21 15:52:51 +0100
commit141b1f40d93ab521a35ecfed97ff9230e32ddd94 (patch)
tree06000b9e655ce200a22d7b71a2e64e84443922ff
parent57c0d1cc3da53bce340be25924372cbcb024d184 (diff)
downloadblog-141b1f40d93ab521a35ecfed97ff9230e32ddd94.tar.gz
blog-141b1f40d93ab521a35ecfed97ff9230e32ddd94.zip
Publish "Making docker-compose easier with wdocker"
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#+TITLE: Making docker-compose easier with wdocker
+#+DATE: 2016-02-21
+#+COLESLAW_TAGS: wdocker docker docker-compose
#+OPTION: num:nil
* Introduction
diff --git a/wdocker_compose.post b/wdocker_compose.post
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+;;;;;
+title: Making docker-compose easier with wdocker
+date: 2016-02-21
+tags: wdocker docker docker-compose
+format: html
+;;;;;
+
+<div id="outline-container-orgheadline1" class="outline-2">
+<h2 id="orgheadline1"><span class="section-number-2">1</span> Introduction</h2>
+<div class="outline-text-2" id="text-1">
+<p>
+<a href="https://github.com/babab/wdocker">wdocker</a> is a little utility written by a <a href="https://benjamin.althu.es">friend</a> and former colleague
+of mine. It allows you to define commands for it in a
+<code>Dockerfile</code>. He wrote it because he used a lot of composite
+commands when writing docker images like:
+</p>
+
+<div class="org-src-container">
+
+<pre class="src src-sh">docker stop CONTAINER &amp;&amp; docker rm CONTAINER &amp;&amp; docker rmi IMAGE &amp;&amp; <span class="org-sh-escaped-newline">\</span>
+ docker build -t IMAGE &amp;&amp; docker run --name CONTAINER IMAGE
+</pre>
+</div>
+
+<p>
+By using wdocker to define a command he can greatly simplify his own
+workflow. Let's call it rebuild:
+</p>
+
+<div class="org-src-container">
+
+<pre class="src src-dockerfile"><span class="org-comment-delimiter">#</span><span class="org-comment">wd# container = CONTAINER</span>
+<span class="org-comment-delimiter">#</span><span class="org-comment">wd# image = IMAGE</span>
+<span class="org-comment-delimiter">#</span><span class="org-comment">wd# stop = docker stop {container}</span>
+<span class="org-comment-delimiter">#</span><span class="org-comment">wd# rm = docker rm {container}</span>
+<span class="org-comment-delimiter">#</span><span class="org-comment">wd# rmi = docker rmi {container}</span>
+<span class="org-comment-delimiter">#</span><span class="org-comment">wd# build = docker build -t {image}</span>
+<span class="org-comment-delimiter">#</span><span class="org-comment">wd# run = docker run --name {container} {image}</span>
+
+<span class="org-comment-delimiter">#</span><span class="org-comment">wd# rebuild: {stop} &amp;&amp; {rm} &amp;&amp; {rmi} &amp;&amp; {build} &amp;&amp; {run}</span>
+
+<span class="org-keyword">FROM</span> ubuntu
+
+<span class="org-comment-delimiter"># </span><span class="org-comment">...</span>
+</pre>
+</div>
+
+<p>
+Now he can use the following command instead of the list presented
+before:
+</p>
+
+<pre class="example">
+wdocker rebuild
+</pre>
+</div>
+</div>
+
+<div id="outline-container-orgheadline2" class="outline-2">
+<h2 id="orgheadline2"><span class="section-number-2">2</span> Syntax</h2>
+<div class="outline-text-2" id="text-2">
+<p>
+wdocker has very simple syntax. You can define variables and
+commands:
+</p>
+
+<pre class="example">
+#wd# variable = value
+#wd# command: program
+</pre>
+
+<p>
+Variables can be used by putting them in braces, including in other
+variables, as you've seen in the first example.
+</p>
+
+<pre class="example">
+#wd# variable = -l
+#wd# list: ls {variable}
+</pre>
+
+<p>
+This would run <code>ls -l</code> when the command <code>wdocker list</code> is called.
+</p>
+
+<p>
+As you can see you're not limited to using docker in your wdocker
+commands. This property is what allows me to use wdocker in my
+workflow.
+</p>
+</div>
+</div>
+
+<div id="outline-container-orgheadline3" class="outline-2">
+<h2 id="orgheadline3"><span class="section-number-2">3</span> Combining with docker-compose</h2>
+<div class="outline-text-2" id="text-3">
+<p>
+I started using docker not too long ago at work to develop our
+projects in. This is nice because it allows me to completely isolate
+my development environments. Since we have a few processes running
+together a single docker image isn't a great option, so I use
+docker-compose to define and combine the containers I need.
+</p>
+
+<p>
+As a side-effect this requires me to write long commands to do
+something like run rspec tests:
+</p>
+
+<pre class="example">
+docker-compose run --rm -e RACK_ENV=test -e RAILS_ENV=test \
+ container bundle exec rspec
+</pre>
+
+<p>
+The alternative is defining a specialized test container with a
+bogus entry command (such as <code>true</code>) and use that, which would still
+make the command:
+</p>
+
+<pre class="example">
+docker-compose run --rm test-container bundle exec rspec
+</pre>
+
+<p>
+Instead I can define a wdocker command in the <code>Dockerfile</code> used to
+build the containers used:
+</p>
+
+<div class="org-src-container">
+
+<pre class="src src-dockerfile"><span class="org-comment-delimiter">#</span><span class="org-comment">wd# rspec: docker-compose run --rm -e RACK_ENV=test -e RAILS_ENV=test container bundle exec rspec</span>
+
+<span class="org-keyword">FROM</span> ruby
+
+<span class="org-comment-delimiter">#</span><span class="org-comment">...</span>
+</pre>
+</div>
+
+<p>
+Now I can run the following, much shorter, command to run the rspec
+tests:
+</p>
+
+<pre class="example">
+wdocker rspec
+</pre>
+
+<p>
+We also use cucumber for some other tests, which is even longer to
+type in, adding the <code>cucumber</code> command is easy:
+</p>
+
+<div class="org-src-container">
+
+<pre class="src src-dockerfile"><span class="org-comment-delimiter">#</span><span class="org-comment">wd# rspec: docker-compose run --rm -e RACK_ENV=test -e RAILS_ENV=test container bundle exec rspec</span>
+<span class="org-comment-delimiter">#</span><span class="org-comment">wd# cucumber: docker-compose run --rm -e RACK_ENV=test -e RAILS_ENV=test container bundle exec cucumber</span>
+
+<span class="org-keyword">FROM</span> ruby
+
+<span class="org-comment-delimiter"># </span><span class="org-comment">...</span>
+</pre>
+</div>
+
+<p>
+Now I can run <code>wdocker cucumber</code> as well.
+</p>
+
+<p>
+The latest git version of wdocker passes any arguments after the
+command name directly to the command to be executed. So if I need to
+run tests in a single spec file I can just do:
+</p>
+
+<pre class="example">
+wdocker rspec spec/models/mymodel_spec.rb
+</pre>
+
+<p>
+We have two commands defined now that are 90% the same. I always use
+the <code>--rm</code> switch to remove the started container after it's done, I
+don't want a lot of containers piling up. I also always have to use
+<code>bundle exec</code> to run commands, since the containers don't use rvm or
+add the script directories to <code>$PATH</code>. We can extract them to some
+variables:
+</p>
+
+<div class="org-src-container">
+
+<pre class="src src-dockerfile"><span class="org-comment-delimiter">#</span><span class="org-comment">wd# run = docker-compose run --rm</span>
+<span class="org-comment-delimiter">#</span><span class="org-comment">wd# exec = bundle exec</span>
+<span class="org-comment-delimiter">#</span><span class="org-comment">wd# test = -e RACK_ENV=test -e RAILS_ENV=test</span>
+
+<span class="org-comment-delimiter">#</span><span class="org-comment">wd# rspec: {run} {test} container {exec} rspec</span>
+<span class="org-comment-delimiter">#</span><span class="org-comment">wd# cucumber: {run} {test} container {exec} cucumber</span>
+
+<span class="org-keyword">FROM</span> ruby
+
+<span class="org-comment-delimiter"># </span><span class="org-comment">...</span>
+</pre>
+</div>
+
+<p>
+Right now these commands always use the <code>container</code> service defined
+in <code>docker-compose.yml</code>. I could add it to the <code>run</code> command, but I
+might need to run some commands on another container, but I can
+define another variable:
+</p>
+
+<div class="org-src-container">
+
+<pre class="src src-dockerfile"><span class="org-comment-delimiter">#</span><span class="org-comment">wd# run = docker-compose run --rm</span>
+<span class="org-comment-delimiter">#</span><span class="org-comment">wd# test = -e RACK_ENV=test -e RAILS_ENV=test</span>
+<span class="org-comment-delimiter">#</span><span class="org-comment">wd# run-test-container = {run} {test} container</span>
+<span class="org-comment-delimiter">#</span><span class="org-comment">wd# exec = bundle exec</span>
+
+<span class="org-comment-delimiter">#</span><span class="org-comment">wd# rspec: {run-test-container} {exec} rspec</span>
+<span class="org-comment-delimiter">#</span><span class="org-comment">wd# cucumber: {run-test-container} {exec} cucumber</span>
+
+<span class="org-keyword">FROM</span> ruby
+
+<span class="org-comment-delimiter"># </span><span class="org-comment">...</span>
+</pre>
+</div>
+
+<p>
+Now you also see that variables can be nested in other variables.
+</p>
+
+<p>
+If you ever forget what you defined or if the mix of commands and
+variables becomes too much for you, you can call the wdocker command
+without arguments to see the commands you defined and the shell
+commands they'll run.
+</p>
+</div>
+</div>