Manage multiple files permissions using puppet - puppet

Question

How do I set file permission from list of file names from cat command?
For example, below command returns 3 file names:
$ cat /tmp/test | grep file
/etc/systemd/file_1.log
/etc/systemd/file_2.log
/etc/systemd/file_3.log
How do I use puppet to run the command, get the file names and then loop the 3 file names and set permission accordingly?

Answer 1

The files are resources and if you want to manage a resource you have to know it's there so dynamically created log files are not easy. If you know the file names already then you can use something like this and pass an array into the file resource.
file { ['/etc/systemd/file_1.log',
'/etc/systemd/file_1.log',
'/etc/systemd/file_1.log'] :
ensure => 'file',
mode => '0644',
owner => 'root',
group => 'root',
}
An other method might be to use an exec
exec { 'chmod 644 /etc/systemd/file_*.log':
path => ['/usr/bin', '/usr/sbin',],
}
But you really need something like an onlyif or unless or this is going to execute every 30 minutes and that breaks the idempotent rule we try and apply with Puppet code where things only change if they need correcting. So you're going to need a command line that'll test the permissions and return a boolean to the onlyif.
There are more details here https://puppet.com/docs/puppet/5.5/types/exec.html
A alternative (and the way I'd do it) would be to expose the contents of that file via an external fact which passes the list of files to Puppet to use in the catalog compilation. An external fact can be a bash script so I'd create a file called /etc/facter/facts.d/logfiles.sh, obviously I'd deploy this using Puppet.
#!/usr/bin/env bash
logfiles=($(grep file /tmp/test))
echo "logfiles=${logfiles[*]}"
Then in my Puppet code I'd have something like this;
$logfiles.each |String $logfile| {
file { $logfile :
ensure => 'file',
mode => '0644',
owner => 'root',
group => 'root',
}
}
So when the Puppet run happens the list of log files will be returned to Puppet via the facts and then each file listed is defined as a resource with the correct permissions.

Answer 2

How do I set file permission from list of file names from cat command?
There are two main alternatives, but I observe first that your example is of the output from grep, not cat, and that the cat in that example is superfluous. Nevertheless, those details don't change the big picture -- substantially the same approaches are applicable for data output by any command.
It would be more idiomatic to write a custom fact that captures the filenames (as of the time of each catalog request), and use that information to create the appropriate File resources.
Custom facts are not that hard, but the full details are more than would be appropriate for an SO answer. Supposing that you have a fact $facts['systemd_logs'] whose value is an array of the absolute filenames, you can compactly express the whole group of wanted File resources like so:
file { $facts['systemd_logs']:
mode => '0644',
}
(or whatever mode it is that you want).
It would be quicker (and dirtier) to use an Exec resource to run an appropriate command:
exec { 'ensure correct file permissions':
command => 'chmod 0644 $(/bin/grep file /tmp/test)',
onlyif => '/bin/grep -q file /tmp/test',
provider => 'shell',
}