Despite no change in content, agent log file indicates content changed in each catalog run

[Ed Young]

Despite no change in file (actually, template) content, with each catalog run I get such log output as: 

Aug 19 20:49:50 app-dev puppet-agent[30132]: (/Stage[main]/Apache-httpd/File[/etc/httpd/conf/httpd.conf]/content) content changed '{md5}b8a5c22154e45771bc09ef5c34

[root@chimps-dev puppet]# service puppet restart                                                        │603e7f' to '{md5}14699f9c769a61cbc6cc5e2c2a7465ff'

Which indicates that the file changed on the puppet master and so will be updated on the agent. 

This happens consistently and results in a service restart when the files are config files like httpd.conf. 

this is with puppet 2.6.18 on RHEL 6 (puppet master) and RHEL 5 (puppet agent) 

Here is my init.pp in my apache module. Note that I'm using templates only (nothing in my files directory) 

class apache-httpd {

  $moduleName = "apache-httpd"

  file { '/etc/httpd/conf/httpd.conf':

       owner => "root",

       group => "root",

       mode => 0644,

       ensure => 'file',

#       source => 'puppet:///modules/apache-httpd/etc/httpd/conf/httpd.conf',

       content => template('apache-httpd/etc/httpd/conf/httpd.conf.erb'),

  }

file { '/etc/httpd/conf.d/proxy_ajp.conf':

       owner => "root",

       group => "root",

       mode => 0644,

       ensure => 'file',

#       source => 'puppet:///modules/apache-httpd/etc/httpd/conf.d/proxy_ajp.conf',

       content => template('apache-httpd/etc/httpd/conf.d/proxy_ajp.conf.erb'),

  }

  file { '/etc/httpd/conf.d/ssl.conf':

       owner => "root",

       group => "root",

       mode => 0644,

       ensure => 'file',

##       source => 'puppet:///modules/apache-httpd/etc/httpd/conf.d/ssl.conf',

       content => template('apache-httpd/etc/httpd/conf.d/ssl.conf.erb'),

  }

}

[Rahul Khengare]

Hi Ed,

   Puppet execute their file resource only if contents of target file get changed at the before execution of puppet run.

I checked your problem on RHEL-6.2 using puppet version 2.7.12, httpd.conf file not transferred each time if there is not change in the contents.   

You may have to check the contents of httpd.conf file before and running the puppet(use vimdiff command). There may possibility that httpd.conf file is edited by another service, 

Thanks and Regards,

Rahul Khengare,

NTT DATA OSS Center, Pune, India.      

[Stephen Gran]

On 22/08/13 16:39, Ed Young wrote:
> Thanks for the response. There doesn't seem to be another process
> updating the files on before the puppet run. I believe the issue was the
> presence of a dynamic tag on the template file.
>
> The problem appears to be that the tag <%= @uptime_seconds %> was in
> some of the configuration files. When I removed that tag from the apache
> config files, and from the tomcat6 config files, there were no longer
> any updates due to file changes.
>
> The <%= @uptime_seconds %> appears to be set before execution of the
> puppet run, which I didn't expect, since tags such as <%= @fqdn %>
> resolve on the target agent node.
>
> Does this sound correct?
> if so, how do I know which tags or variables will be set before the
> puppet execution, and which are set on the agent side after the catalog
> run?

@uptime_seconds and @fqdn are both facts. Facts are supplied by the
agent. In this case, uptime_seconds is how many seconds the node has
been up. This will obviously change between runs. For a list of what
facts are available, you can run `facter -p` on the node.

Cheers,
--
Stephen Gran
Senior Systems Integrator - theguardian.com
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[Ed Young]

Regarding that fqdn and uptime_seconds are facts, that is understood. 

The agent node updating the file and triggered the content change may be obvious to you, but I'm a puppet beginner, and I yet don't have a solid understanding of the catalog run or how, when or where the tags get updated. 

1. I thought that the file on the agent node would never be updated unless the content on the puppet master changed which would trigger the catalog run and force the update. 

2. Instead, it appears that the agent node will trigger an update per it's runinterval, resolve the dynamic tags and if a fact needs updating, it will update the corresponding file and generate the content changed message I saw in the the agent node log. 

Is this close to correct? 

Meanwhile I'm going through ProPuppet and everything I can find on the puppetlabs site and hope to have a better understanding. 

[Rahul Khengare]

Ed, It sound correct. The tag/facter value @uptime_seconds changes each time you run the puppet on agent machine.

During the puppet catalog run, puppet first fetch the facter value and then apply the puppet manifests. So whatever the value of facter are set before the puppet manifests deployment.  

You can view facter values using 'facter -p'. 

You may look for tag concept it might help. 

http://projects.puppetlabs.com/projects/1/wiki/Using_Tags

Thanks and Regards,

Rahul Khengare,

NTT DATA OSS Center, Pune, India.      

     

On Thu, Aug 22, 2013 at 9:09 PM, Ed Young <e...@summitbid.com> wrote:

Thanks for the response. There doesn't seem to be another process updating the files on before the puppet run. I believe the issue was the presence of a dynamic tag on the template file. 

The problem appears to be that the tag <%= @uptime_seconds %> was in some of the configuration files. When I removed that tag from the apache config files, and from the tomcat6 config files, there were no longer any updates due to file changes. 

The <%= @uptime_seconds %> appears to be set before execution of the puppet run, which I didn't expect, since tags such as <%= @fqdn %> resolve on the target agent node. 

Does this sound correct? 

if so, how do I know which tags or variables will be set before the puppet execution, and which are set on the agent side after the catalog run? 

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[Stephen Gran]

On 22/08/13 17:50, Ed Young wrote:
> Regarding that fqdn and uptime_seconds are facts, that is understood.
>
> The agent node updating the file and triggered the content change may be
> obvious to you, but I'm a puppet beginner, and I yet don't have a solid
> understanding of the catalog run or how, when or where the tags get
> updated.
>
> 1. I thought that the file on the agent node would never be updated
> unless the content on the puppet master changed which would trigger the
> catalog run and force the update.
> 2. Instead, it appears that the agent node will trigger an update per
> it's runinterval, resolve the dynamic tags and if a fact needs updating,
> it will update the corresponding file and generate the content changed
> message I saw in the the agent node log.
>
> Is this close to correct?
>
> Meanwhile I'm going through ProPuppet and everything I can find on the
> puppetlabs site and hope to have a better understanding.

I think the glue that you're missing is that, while the template on the
puppetmaster has not changed, the value of the variable in the template
has changed.

Variables in templates can come from many places in puppet. In this
particular case, you (or someone) has used a fact. Facts values are
filled in by the agent on the node at the start of a run, before
catalogue compliation, so that they are available to the master for use
in the catalogue.

http://docs.puppetlabs.com/guides/custom_facts.html may be of some help
to you.