On Tuesday, October 2, 2012 3:36:10 PM UTC-5, am-aaron wrote:
>
> hello:
>
> i currently am using Puppet to run some commands in a sequence. there are
> two sequences of exec resources. we found that we cannot use require =>
> Exec and it does not work at all as expected. here is some sample code.
>
> exec { "exec-AAA":
> command => "/bin/true",
> returns => 0,
> notify => Exec["exec-BBB"],
> }
> exec { "exec-BBB":
> refreshonly => true,
> command => "/bin/false",
> returns => 0,
> notify => Exec["exec-CCC"],
> }
> exec { "exec-CCC":
> refreshonly => true,
> command => "/bin/touch /tmp/CCC",
> returns => 0,
> }
>
> exec { "exec-DDD":
> require => Exec["exec-CCC"],
> command => "/bin/true",
> returns => 0,
> notify => Exec["exec-EEE"],
> }
> exec { "exec-EEE":
> refreshonly => true,
> command => "/bin/false",
> notify => Exec["exec-FFF"],
> }
> exec { "exec-FFF":
> refreshonly => true,
> command => "/bin/touch /tmp/FFF",
> returns => 0,
> }
>
> *ms1:/root/aaron> puppet apply t1.pp*
>
> notice: /Stage[main]//Exec[exec-AAA]/returns: executed successfully
> err: /Stage[main]//Exec[exec-BBB]: Failed to call refresh: /bin/false
> returned 1 instead of one of [0] at /root/aaron/t1.pp:11
> notice: /Stage[main]//Exec[exec-DDD]/returns: executed successfully
> err: /Stage[main]//Exec[exec-EEE]: Failed to call refresh: /bin/false
> returned 1 instead of one of [0] at /root/aaron/t1.pp:28
> notice: Finished catalog run in 0.36 seconds
>
> in the example above, how did Exec["exec-DDD"] run when Exec["exec-CCC"]
> did not run and Exec["exec-DDD"] require Exec["exec-CCC"]?
>
> *ms1:/root/aaron> puppet apply --debug t1.pp*
>
> info: Applying configuration version '1349209769'
> debug: /Stage[main]//Exec[exec-DDD]/require: requires Exec[exec-CCC]
> debug: /Stage[main]//Exec[exec-DDD]/notify: subscribes to Exec[exec-EEE]
> debug: /Stage[main]//Exec[exec-BBB]/notify: subscribes to Exec[exec-CCC]
> debug: /Stage[main]//Exec[exec-AAA]/notify: subscribes to Exec[exec-BBB]
> debug: /Stage[main]//Exec[exec-EEE]/notify: subscribes to Exec[exec-FFF]
> debug: /Schedule[never]: Skipping device resources because running on a
> host
> debug: /Schedule[daily]: Skipping device resources because running on a
> host
> debug: /Schedule[monthly]: Skipping device resources because running on a
> host
> debug: /Schedule[puppet]: Skipping device resources because running on a
> host
> debug: /Schedule[hourly]: Skipping device resources because running on a
> host
> debug: /Schedule[weekly]: Skipping device resources because running on a
> host
> debug: Exec[exec-AAA](provider=posix): Executing '/bin/true'
> debug: Executing '/bin/true'
> notice: /Stage[main]//Exec[exec-AAA]/returns: executed successfully
> debug: /Stage[main]//Exec[exec-AAA]: The container Class[Main] will
> propagate my refresh event
> info: /Stage[main]//Exec[exec-AAA]: Scheduling refresh of Exec[exec-BBB]
> debug: Exec[exec-BBB](provider=posix): Executing '/bin/false'
> debug: Executing '/bin/false'
> err: /Stage[main]//Exec[exec-BBB]: Failed to call refresh: /bin/false
> returned 1 instead of one of [0] at /root/aaron/t1.pp:11
> debug: Exec[exec-DDD](provider=posix): Executing '/bin/true'
> debug: Executing '/bin/true'
> notice: /Stage[main]//Exec[exec-DDD]/returns: executed successfully
> debug: /Stage[main]//Exec[exec-DDD]: The container Class[Main] will
> propagate my refresh event
> info: /Stage[main]//Exec[exec-DDD]: Scheduling refresh of Exec[exec-EEE]
> debug: Exec[exec-EEE](provider=posix): Executing '/bin/false'
> debug: Executing '/bin/false'
> err: /Stage[main]//Exec[exec-EEE]: Failed to call refresh: /bin/false
> returned 1 instead of one of [0] at /root/aaron/t1.pp:28
> debug: Class[Main]: The container Stage[main] will propagate my refresh
> event
> debug: Finishing transaction 70054935787440
> debug: Storing state
> debug: Stored state in 0.06 seconds
> notice: Finished catalog run in 0.37 seconds
> debug: /File[/var/lib/puppet/rrd]/seluser: Found seluser default
> 'system_u' for /var/lib/puppet/rrd
> debug: /File[/var/lib/puppet/rrd]/selrole: Found selrole default
> 'object_r' for /var/lib/puppet/rrd
> debug: /File[/var/lib/puppet/rrd]/seltype: Found seltype default
> 'puppet_var_lib_t' for /var/lib/puppet/rrd
> debug: /File[/var/lib/puppet/rrd]/selrange: Found selrange default 's0'
> for /var/lib/puppet/rrd
> debug: Finishing transaction 70054934905120
> debug: Recieved report to process from ms1
> debug: Processing report from ms1 with processor Puppet::Reports::Store
>
> as you can see in the debug run, even though Exec["exec-DDD"] require
> Exec["exec-CCC"], and the latter does not run, the former runs. what is
> going on here?
>
>
The 'require' metaparameter is no different for Exec resources than for any
other resource type: foo { 'myfoo': require => Bar['mybar'] } means that
when the agent applies the catalog, it must successfully *apply* resource
Bar['mybar'] before it applies resource Foo['myfoo']. Your issue is
basically about what it means to "apply" an Exec.
In simple cases, "applying" an Exec involves running its command, and the
success or failure of the resource is based on the command's exit status.
When you set "refreshonly => true" on an Exec resource, that does not make
application of the resource conditional. Puppet will always (attempt to)
apply every resource in the catalog it receives. Instead, "refreshonly =>
true" makes the *steps taken* to apply the Exec conditional. If such an
Exec has not been signaled then applying it is a no-op that automatically
succeeds. That's why you are seeing a resource that 'require's
Exec['exec-CCC'] being applied even though CCC's command is never run.
Note also that Exec has other parameters that can lead to instances being
applied successfully without their commands being run. The 'creates',
'onlyif', and 'unless' parameters all provide mechanisms for Puppet to
decide that an Exec resource is already in sync without running its (main)
command. Applying a resource of any type that is already in sync is also a
no-op that automatically succeeds.
Presumably, the question arises from attempts to develop manifests for a
particular configuration objective. If you give us some details about the
job you're trying to perform, then we may be able to give you
better-targeted advice.
John
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