False cognates: puppet and environments

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One of the tasks I have is to build some separation between the production environment and test/integration environments. As we approach that Very Big Deadline I've talked about, this is a pretty significant task. Dev processes that we've been using for a really long time now need to change in order to provide the separation we need, and that's some tricky stuff.

One of the ways I plan on accomplishing this is through the use of Environments in Puppet. This looks like a great way to allow automation while delivering different code to different environments. Nifty keen stuff.

But it requires that I re-engineer our current Puppet environment, which is a single monolithic all-or-nothing repo to accommodate this. This is fairly straight-forward, as suggested by the Puppet Docs:

If the values of any settings in puppet.conf reference the $environment variable (like modulepath = $confdir/environments/$environment/modules:$confdir/modules, for example), the agent's environment will be interpolated into them.

So if I need to deliver a different set of files to production, such as a different authorized_keys file, I can drop that into $confdir/environments/production/modules and all will be swell.

So I tried to set that up. I made the environment directory, changed the puppet.conf file to reflect that, made an empty module directory for the module that'd get the changed files (but not put the files in there yet), and ran a client against it.

It didn't work so well.

The error I was getting on the puppetmaster was err: Could not find class custommod for clunod-wk0130.sub.example.local at /etc/puppet/manifests/site.pp:84 on node clunod-wk0130.sub.example.local

I checked eight ways from Sunday for spelling mistakes, bracket errors, and other such syntax problems but could not find out why it was having trouble locating the custommod directory. I posted on ServerFault for some added help, but didn't get much beyond, "Huh, it SHOULD work that way," which wasn't that helpful.

I decided that I needed to debug where it was searching for modules since it manifestly wasn't seeing the one staring it in the face. For this I used strace, which produced an immense logfile. Grepping out the 'stat' calls as it checked the import statements, I noticed something distinctly odd.


It was attempting to read in the init.pp file for the custommod, even though there wasn't a file there. And what's more, it wasn't then re-trying under /etc/puppet/modules/custommod/manifests/init.pp. Clearly, the modulepath statement does not work like the $PATH variable in bash and every other shell I've used. In those, if it fails to find a command in (for example) /usr/local/bin, it'll then try /usr/bin, and then ~/bin until it finds the file.

The modulepath statement in puppet.conf is focused on modules, not individual files.

This is a false cognate. By having that empty module in the production environment, I was in effect telling Puppet that the Production environment doesn't have that module. Also, my grand plan to provide a different authorized_keys file in the Production environment requires me to have a complete module for the Production environment directory, not just the one or two files I want changed.

Good to know.

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Yes, this is what puts me off using environments in Puppet. You may want something more like extlookup: https://github.com/ripienaar/puppet-extlookup