On Saturday, June 4, 2016 at 7:20:19 PM UTC-5, Helmut Schneider wrote:
>
> Hi,
>
> I'm new to puppet and read docs as much as possible, so forgive some
> confusion in my code.
>
>
[...]
> nodes/xyz.yaml:
> packages:
> - postfix
> - wget
> apacheModules:
> - mpm_prefork
> - php
> - ssl
>
>
[...]
> nodes.pp:
> case $operatingsystem {
> /^(Debian|Ubuntu)$/: {
>
[...]
$ubuntuDefaultApacheModules = hiera_array ('apacheModules', '',
> 'ubuntu-common')
> $ubuntuExtraApacheModules = hiera_array ('apacheModules', '',
> "nodes/$fqdn")
> $ubuntuApacheModules = [ $ubuntuDefaultApacheModules,
> $ubuntuExtraApacheModules ]
> hiera_include ('classes', '', 'ubuntu-common')
> }
> default: {
> }
> }
> hiera_include ('classes', '', "nodes/$fqdn")
> [...]
> install-packages { [ $ubuntuDefaultPackages, $packages ]: } <= works
> apache24::modules { $ubuntuApacheModules: } <= fails
>
> The error is:
>
> Error: Could not retrieve catalog from remote server: Error 400 on
> SERVER: Duplicate declaration: Apache24::Modules[mpm_prefork] is
> already declared in file
> /etc/puppet/environments/production/manifests/nodes.pp:54; cannot
> redeclare at /etc/puppet/environments/production/manifests/nodes.pp:54
> on node xyz
>
> Apache24::Modules[mpm_prefork] varies. I'm using the apache class from
> puppetlabs. Apache24::Modules is called only from nodes.pp, there are
> no duplicates.
>
>
If there are no duplicates among your Hiera data, then it follows that you
are *creating* the duplication in your manifests, which indeed appears to
be plausible. In any event, you do appear to be using Hiera in a less than
efficient manner. Here are some important considerations that bear on the
question:
- The choice among functions hiera(), hiera_array(), and hiera_hash()
has little to do with the expected type of the value returned. Although
the latter two do return an array and a hash, respectively, the plain
hiera() function will also return one of those if that is the type of
the data it finds associated with the given key. The primary distinction
among these is the lookup strategy. In particular, the hiera_array()
function performs an "array-merge" lookup, which collects data from the
whole hierarchy, whereas the plain hiera() function performs a priority
lookup, returning only the value from the highest-priority hierarchy level
that provides one.
- The third parameter to the hiera-family functions is optional, and
usually unneeded. Additionally, I suspect its docs are misleading for
hiera_hash() and hiera_array(): whereas it does cause the specified
hierarchy level to be consulted, first, it does not makes sense for these
two functions for the search to stop there in the event that the key is
found in the override level. That ought to apply only to the hiera()
function, from which the docs for that argument in the other two functions
appear to have been copied.
> My question is: Is the approach itself correct? I want to pass
> $packages and $apachemodules to a class that does the install.
>
>
There's nothing inherently wrong with constructing those arrays and using
them as resource titles. There's nothing any more wrong about using
array-titled, resource-like class declarations than there is about using
resource-like class declarations in general. If you use array titles,
however, then you undertake responsibility to ensure that the arrays
contain no duplicate elements. In this case, it appears that you have
ensured the opposite.
Consider this call:
hiera_array ('apacheModules', '', 'ubuntu-common')
It performs an array-merge lookup for key 'apacheModules', with hierarchy
level 'ubuntu-common' inserted at the top of the hierarchy. That level is
already in the hierarchy for the node, or so I must presume. Now remember
that an array-merge lookup collects data from every level in the hierarchy,
so if that duplicate level contains any data for the requested key then you
will automatically get dupes for all those data.
Even if you weren't getting dupes by virtue of having the same hierarchy
level consulted twice, it looks like you have a second avenue for dupes.
You are performing two array-merge lookups and then concatenating the
results. Since each array-merge lookup will collect data from the whole
hierarchy (plus, in your case, an extra level), the two sets of results you
are concatenating will have many elements in common, so concatenating them
produces dupes.
The bottom line is that you're making this a lot harder than it needs to
be. You have no need to use a manual hierarchy override if you simply
define the hierarchy appropriately, as the details of your error suggest
you have already done. And you do not need separate array-merge lookups
for each key: with the hierarchy defined correctly, a single one will do
what you seem to be trying to do manually. In fact, even your 'case'
statement is a bit suspect. With appropriate use of fact interpolation in
your hierarchy definition, you should be able to reduce [the section you
presented of] your nodes.pp to just this:
$packages = hiera_array ('packages', [])
$apacheModules = hiera_array ('apacheModules', [])
hiera_include ('classes')
install-packages { $packages: }
apache24::modules { $apacheModules: }
John
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