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書名： Puppet 3 Cookbook
作者名： John Arundel
本章字數： 486字
更新時間： 2021-04-09 23:52:26

Automatic syntax checking with Git hooks

It would be nice if we knew there was a syntax error in the manifest before we even committed it. You can have Puppet check the manifest using the puppet parser validate command:

ubuntu@cookbook:~/puppet$ puppet parser validate manifests/nodes.pp
Error: Could not parse for environment production: Syntax error at end of file; expected '}' at /home/ubuntu/puppet/manifests/nodes.pp:3
Error: Try 'puppet help parser validate' for usage

This is especially useful because a mistake anywhere in the manifest will stop Puppet from running on any node, even on nodes that don't use that particular part of the manifest. So checking in a bad manifest can cause Puppet to stop applying updates to production for some time, until the problem is discovered, and this could potentially have serious consequences. The best way to avoid this is to automate the syntax check, by using a pre-commit hook in your version control repo.

How to do it…

Follow these steps:

In your Puppet repo, create a new hooks directory:
```
ubuntu@cookbook:~/puppet$ mkdir hooks
```

Create the file hooks/check_syntax.sh with the following contents (based on a script by Puppet Labs):

#!/bin/sh

syntax_errors=0
error_msg=$(mktemp /tmp/error_msg.XXXXXX)

if git rev-parse --quiet --verify HEAD > /dev/null
then
    against=HEAD
else
    # Initial commit: diff against an empty tree object
    against=4b825dc642cb6eb9a060e54bf8d69288fbee4904
fi

# Get list of new/modified manifest and template files
  to check (in git index)
for indexfile in `git diff-index --diff-filter=AM --
  name-only --cached $against | egrep '\.(pp|erb)'`
do
    # Don't check empty files
    if [ `git cat-file -s :0:$indexfile` -gt 0 ]
    then
        case $indexfile in
            *.pp )
                # Check puppet manifest syntax
                git cat-file blob :0:$indexfile | 
                  puppet parser validate > $error_msg ;;
            *.erb )
                # Check ERB template syntax
                git cat-file blob :0:$indexfile | 
                  erb -x -T - | ruby -c 2> $error_msg >
                    /dev/null ;;
        esac
        if [ "$?" -ne 0 ]
        then
            echo -n "$indexfile: "
            cat $error_msg
            syntax_errors=`expr $syntax_errors + 1`
        fi
    fi
done

rm -f $error_msg

if [ "$syntax_errors" -ne 0 ]
then
    echo "Error: $syntax_errors syntax errors found,
      aborting commit."
    exit 1
fi

Set execute permission for the hook script with the following command:
```
ubuntu@cookbook:~/puppet$ chmod a+x .hooks/check_syntax.sh
```

Add the following task to your Rakefile:

desc "Add syntax check hook to your git repo"
task :add_check do
  here = File.dirname(__FILE__)
  sh "ln -s #{here}/hooks/check_syntax.sh
    #{here}/.git/hooks/pre-commit"
  puts "Puppet syntax check hook added"
end

Run the following command:

ubuntu@cookbook:~/puppet$ rake add_check
ln -s /home/ubuntu/puppet/hooks/check_syntax.sh
 /home/ubuntu/puppet/.git/hooks/pre-commit
Puppet syntax check hook added

How it works…

The check_syntax.sh script will prevent you from committing any files with syntax errors:

ubuntu@cookbook:~/puppet$ git commit -m "test commit"
Error: Could not parse for environment production: Syntax error at
 '}' at line 3
Error: Try 'puppet help parser validate' for usage
manifests/nodes.pp: Error: 1 syntax errors found, aborting commit.

If you add the hooks directory to your Git repo, anyone who has a checkout can run the rake add_check task and get this syntax checking behavior.

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Puppet 3 Cookbook

Automatic syntax checking with Git hooks

How to do it…

How it works…