50 lines
1.5 KiB
Markdown
50 lines
1.5 KiB
Markdown
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---
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page_title: "Tips & Tricks - Vagrantfile"
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sidebar_current: "vagrantfile-tips"
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---
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# Tips & Tricks
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The Vagrantfile is a very flexible configuration format. Since it is just
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Ruby, there is a lot you can do with it. However, in that same vein, since
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it is Ruby, there are a lot of ways you can shoot yourself in the foot. When
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using some of the tips and tricks on this page, please take care to use them
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correctly.
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## Loop Over VM Definitions
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If you want to apply a slightly different configuration to many
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multi-machine machines, you can use a loop to do this. For example, if
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you wanted to create three machines:
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<pre class="prettyprint">
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(1..3).each do |i|
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config.vm.define "slave-#{i}" do |slave|
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slave.vm.provision "shell",
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inline: "echo hello from slave #{i}"
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end
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end
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</pre>
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<strong>Warning:</strong> The inner portion of multi-machine definitions
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and provider overrides are lazy-loaded. This can cause issues if you change
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the value of a variable used within the configs. For example, the loop below
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<em>does not work</em>:
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<pre class="prettyprint">
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# THIS DOES NOT WORK!
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for i in 1..3 do
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config.vm.define "slave-#{i}" do |slave|
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slave.vm.provision "shell",
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inline: "echo hello from slave #{i}"
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end
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end
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</pre>
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The "for i in ..." construct in Ruby actually modifies the value of `i`
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for each iteration, rather than making a copy. Therefore, when you run this,
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every slave will actually provision with the same text.
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This is an easy mistake to make, and Vagrant can't really protect against it,
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so the best we can do is mention it here.
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