mirror of https://github.com/zulip/zulip.git
36 lines
1.3 KiB
Markdown
36 lines
1.3 KiB
Markdown
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Puppet Specific Facts
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=====================
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Facter is meant to stand alone and apart from Puppet. However, Facter often
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runs inside Puppet and all custom facts included in the stdlib module will
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almost always be evaluated in the context of Puppet and Facter working
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together.
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Still, we don't want to write custom facts that blow up in the users face if
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Puppet is not loaded in memory. This is often the case if the user runs
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`facter` without also supplying the `--puppet` flag.
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Ah! But Jeff, the custom fact won't be in the `$LOAD_PATH` unless the user
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supplies `--facter`! You might say...
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Not (always) true I say! If the user happens to have a CWD of
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`<modulepath>/stdlib/lib` then the facts will automatically be evaluated and
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blow up.
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In any event, it's pretty easy to write a fact that has no value if Puppet is
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not loaded. Simply do it like this:
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Facter.add(:node_vardir) do
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setcode do
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# This will be nil if Puppet is not available.
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Facter::Util::PuppetSettings.with_puppet do
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Puppet[:vardir]
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end
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end
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end
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The `Facter::Util::PuppetSettings.with_puppet` method accepts a block and
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yields to it only if the Puppet library is loaded. If the Puppet library is
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not loaded, then the method silently returns `nil` which Facter interprets as
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an undefined fact value. The net effect is that the fact won't be set.
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