Re: [Puppet Users] Iterate over array to mount NFS directories

Luke Bigum
Wed, 26 Sep 2012 08:51:47 -0000

Hi Forrie,

My example below uses a defined type
(http://docs.puppetlabs.com/puppet/2.7/reference/lang_defined_types.html) to
group two related resources together, in this case the File resource for
the mount point and the Mount resource for the NFS mount itself.

To answer your first question, no, "ensure=>absent" in a Mount
resource
will not remove the mount point directory. That is why I''ve wrapped the
File and Mount point in a define, so you can use one definition of
nfs_mount to control both mount point and NFS mount together, as in your
scenario they are two closely related resources.

You will notice the $state parameter of my defined type is used in two
places: for the ''ensure'' parameter of the Mount (described in
the docs
for the Mount type) and the ''ensure'' parameter of the File.
Since the
ensure parameter of the Mount type takes different arguments to the File
type, I use a selector to transform the Mount point''s state into a
state
I can use in a File resource. The selector (ensure => $state ? {...} )
basically says this:

"If $state is unmounted, the File is absent"
"If $state is absent, the File is absent"
"If $state is anything else, the File is directory"

file { $mount_point:
          ensure => $state ? {
              "unmounted" => absent,
              "absent" => absent,
              default => directory,
          }
}

I just noticed a bug in my original post, it should be "default =>
directory" to create a directory, not a file :-)

http://docs.puppetlabs.com/puppet/2.7/reference/lang_conditional.html#selectors

As for the second question about the iteration, the iteration works the
same way for a defined type as it does for any core Puppet type (File,
Mount, Service, etc). Although it''s not really a procedural
"loop", it''s
just a short hand way of writing out a set of resource definitions with
exactly the same parameters, but the effect is the same.

So doing these :

file { $proddirs: ... }
mount { $proddirs: ... }

is the same as this:

nfs_mount { $proddirs: ... }

Now the $name parameter or is the namevar of the defined type
(http://docs.puppetlabs.com/puppet/2.7/reference/lang_resources.html#namenamevar).
It''s the unique name of the resource, works the same as other Puppet
Types, in the examples below it is the strings "apache" and
"/mnt/server/woof":

package { "apache": }
nfs_mount { "/mnt/server/woof/": }

You can use $name inside a defined type just like any other variable /
parameter.

So in an example use of my defined type, this definition:

nfs_mount{ "201201":
   state  => "mounted",
   server => "nfs-server.domain.com",
   prefix => "/our/prefix",
}

Will result in the following standard Puppet resources:

file { "/our/prefix/201201":
   ensure => "directory",
}
mount { "/our/prefix/201201":
   ensure => "mounted",
   device => "nfs-server.domain.com:/our/prefix/201201",
}

Hopefully that explains the use of the defined type in more detail. If
you have any more questions, please ask :-)

-Luke

On 25/09/12 23:09, Forrie wrote:
> Thank you for your reply :)
>
> The head of the code would need something like this:
>
> $server = "nfs-server.domain.com"
> $prefix = "/our/prefix"
>
> # Arrays to iterate over, which would be a little longer than this
> $proddirs = [ "201201", "201202", "201203" ]
> $testdirs = [ "201201", "201202", "201203" ]
> $devdirs  = [ "201201", "201202", "201203" ]
>
> $nfsopts  = "tcp,hard,intr,rw,bg"
>
> By "iterate" I meant to work through a specific array, such as
above.
>
> Reading through the Mount part of the docs, I don''t believe that
> "absent" will remove the actual directory point, it says:
>
> "Set it to |absent| to unmount (if necessary) and remove the
> filesystem from the fstab"
>
> So I would handle that by running another iteration over an array for
> each section that would have a routine to make sure it''s
"absent" and
> then also rmdir the entry in the filesystem.
>
> I''m not understanding where the below is iterating or over
where... as
> $name would need to be defined somehow.
>
>
> Thanks!
>
>
> On Tuesday, September 25, 2012 5:09:15 AM UTC-4, Luke Bigum wrote:
>
>     Hi Forrie,
>
>     With regards to your iteration question, you would need to use a
>     defined
>     type, something like this (untested):
>
>     define nfs_mount ( $server, $prefix, $state = "mounted" ) {
>          $mount_point = "${prefix}/${name}"
>
>          #If the state is "unmounted" the mount point
''File'' is removed
>          file { $mount_point:
>              ensure => $state ? {
>                  "unmounted" => absent,
>                  "absent" => absent,
>                  default => directory,
>              }
>          }
>
>          mount { $mount_point:
>              ensure => $state,
>              device => "{$server}:${mount_point}",
>          }
>     }
>
>     nfs_mount { $production: server => $server, prefix => $prefix}
>
>     See the documentation for the Mount type in Puppet and it''s
ensure
>     parameter for possible values for $state in the define above -
it''s
>     possible to have entries in /etc/fstab but not actually mounted,
>     which
>     should satisfy your two stage cleanup, or you can just set $state to
>     ''absent'' straight away and clean up the both NFS
mount and mount
>     point.
>     This means you need to maintain two arrays: one of active mount
>     points
>     and one of decomissioned mounts, however you probably don''t
need
>     to keep
>     the decomissioned mounts around for ever, once every server has
>     cleaned
>     themselves up they can be removed from the manifest.
>
>     http://docs.puppetlabs.com/references/latest/type.html#mount
>     <http://docs.puppetlabs.com/references/latest/type.html#mount>
>
>     Hope that helps,
>
>     -Luke
>
>     On 24/09/12 23:43, Forrie wrote:
>     > I have many systems that require NFS mounts for production.
Rather
>     > than have one entry of file{} and mount{} per NFS import, in a
*.pp
>     > file, I''d rather set up and iterate over an array.
Looking at the
>     > docs, I''m not quite sure how to do this properly.  We
have three
>     > groups for which I would need this (production, development, test)
>     > that each have their own NFS mounts.
>     >
>     > here''s what I would use:
>     >
>     > $server = "server.name.com
<http://server.name.com>"
>     > $prefix = "/some/nfs/root"
>     >
>     > # array
>     > production = [
>     >               "dir1",
>     >               "dir2",
>     >               "dir3",
>     >               "dir4",
>     > ] # etc etc
>     >
>     > Then issue a command to iterate and manage those NFS mounts.
>     >
>     > Since these change from time-to-time, and require some pruning...
I
>     > will be left with "unmanaged" resources (ie: directory
mount
>     points)
>     > scattered around that I will need to clean up.  I read through
some
>     > tickets for feature requests and got lost in where this is going
--
>     > however, to keep the place neat and clean, I''d like to
unmanage the
>     > mount points and the fstab entries after.   The idea of manually
>     doing
>     > this from system to system isn''t good.
>     >
>     > I''m still new-ish to puppet, so any pointers would be
appreciated.
>     >
>     >
>     > Thanks.
>     >
>     >
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>
>     --
>     Luke Bigum
>     Senior Systems Engineer
>
>     Information Systems
>     Ph: +44 (0) 20 3192 2520
>     luke....@lmax.com <javascript:> | http://www.lmax.com
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