Re: [Puppet Users] Run a File resource only if another file is missing

[Dan White]

Short Answer: You need to create a custom fact that would drive the decision to create the new file resource.

I just went thru this issue and also performing an action based on whether or not a package (RPM in my case) is installed.

Same answer to both.

For the existence of a file, you can do this:

#!/bin/bash
test -f /var/www/owncloud/config/config.php
rc=$?
echo "is_my_file_there=${rc}"

That goes into /etc/facter/facts.d/ as an executable shell script and then in your manifest:

if $::is_my_file_there != 0 {
file { 'autoconfig.php':
.....
}
}


“Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us.”
Bill Waterson (Calvin & Hobbes)

----- Original Message -----
From: "John Naggets" <hosting...@gmail.com>
To: puppet...@googlegroups.com
Sent: Thursday, May 30, 2013 4:04:29 PM
Subject: [Puppet Users] Run a File resource only if another file is missing

Hi,

I would like to run the File resource below:

file { 'autoconfig.php':
path => '/var/www/owncloud/config/autoconfig.php',
ensure => file,
owner => 'www-data',
group => 'www-data',
content => template("owncloud/autoconfig.php.erb"),
}

only when a specific file (in my case: /var/www/owncloud/config/config.php) is missing. Is this somehow possible? Couldn't find my case in the puppet documentation...

Thanks!
John


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[Matthias Saou]

There are other ways. None are nice and clean, but a custom fact just
for this seems overkill.

Here's a quick example of how I've implemented creating a default
~/.gitconfig for users if it doesn't exist, but not modify it if it's
already there or has been modified.

$gitconfig_user_name = $mymodule::uservar::fullname[$title]
$gitconfig_user_email = "${title}@example.com"
file { "${home}/.gitconfig":
owner => $owner,
group => $group,
mode => '0644',
require => Exec["create-gitconfig-${title}"],
}
exec { "create-gitconfig-${title}":
command => template('mymodule/user/gitconfig.erb'),
require => User[$title],
creates => "${home}/.gitconfig",
}

The gitconfig.erb has the following content :
/bin/cat > <%= home %>/.gitconfig << EOF
[user]
name = <%= @gitconfig_user_name %>
email = <%= @gitconfig_user_email %>
EOF

Basically, just don't have either 'source' nor 'content' for your file
resource, and create the initial content using an exec with the
'creates' condition.

Matthias

[Dan White]

That is an excellent example, but I think you miss the original point:

Your example deals with only one file resource - the dot-gitconfig file
Suppose you only wanted to perform this action if git was installed on the system, and do nothing if it was not ?

This additional requirement puts it closer to the original question and this is where a custom fact is called for in the opinion of several folks on the list including myself.

If you can offer an example that demonstrates otherwise, I would welcome it.
I do not believe it possible without the custom fact and I have several hours of frustrated tinkering to show for it. I wanted to set a parameter in a config file but only if (the config file exists and/or the associated package is installed) and found I could not do it completely from within the manifest.

[Matthias Saou]

Hi,

Indeed, I had missed that John was mentioning two different files
("config.php" vs. "autoconfig.php"). In that case, my only bit of
(useless) advice is : You're not using puppet in the way it's most
efficient, as it's not meant to manage nodes based on changes it
doesn't make itself.

Custom fact, it is...

[Nan Liu]

On Fri, May 31, 2013 at 1:00 AM, Matthias Saou <matt...@saou.eu> wrote:

There are other ways. None are nice and clean, but a custom fact just
for this seems overkill.

Here's a quick example of how I've implemented creating a default
~/.gitconfig for users if it doesn't exist, but not modify it if it's
already there or has been modified.

    $gitconfig_user_name = $mymodule::uservar::fullname[$title]
    $gitconfig_user_email = "${title}@example.com"
    file { "${home}/.gitconfig":
      owner   => $owner,
      group   => $group,
      mode    => '0644',
      require => Exec["create-gitconfig-${title}"],
    }
    exec { "create-gitconfig-${title}":
      command => template('mymodule/user/gitconfig.erb'),
      require => User[$title],
      creates => "${home}/.gitconfig",
    }

A bit off topic, but you should use file attribute replace => false instead of an exec.

Nan

[John Naggets]

Thanks guys for your input. That's correct I am looking to act upon another file's nonexistence... I will go with facter.

>     $gitconfig_user_email = "${tit...@example.com"

[joe]

You should really reconsider how you are going about things and organizing your resources if you have to do stuff like this.

Puppet was never meant to be reactionary in this sense. It's entire purpose is to define the state of the system and enforce that state, not to respond to the state of the system conditionally.

[Matthias Saou]

On Fri, 31 May 2013 07:52:25 -0700
Nan Liu <nan...@gmail.com> wrote:

> A bit off topic, but you should use file attribute replace => false
> instead of an exec.

Indeed. I'm not sure how I've missed that parameter. And it seems to
have existed for a loooooong time. Thanks a lot for correcting me!

Matthias

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