The Puppet master service and the
puppet apply command both load most of their content from modules. (See the page on module structure and behavior for more details.)
Puppet automatically loads modules from one or more directories. The list of directories Puppet will find modules in is called the modulepath.
The modulepath is set by the current node’s environment.
The modulepath is a list of directories separated by the system path-separator character. On *nix systems, this is the colon (
:, as seen above), and on Windows it is the semi-colon (
It is an ordered list, with earlier directories having priority over later ones. See “Loading Content from Modules” below.
Every directory in the modulepath should only contain valid Puppet modules.
The names of those modules must only contain letters, numbers, and underscores. Dashes and periods are no longer valid and cause errors when attempting to use the module.
For details about module contents and structure, see the documentation on modules.
The modulepath is set by the current node’s environment. By default, it is usually something like:
<ACTIVE ENVIRONMENT'S MODULES DIRECTORY>:$codedir/modules:/opt/puppetlabs/puppet/modules
You can view the effective modulepath for any environment by specifying the environment when requesting the setting value:
sudo puppet config print modulepath --section master --environment test /etc/puppetlabs/code/environments/test/modules:/etc/puppetlabs/code/modules:/usr/share/puppet/modules
Each environment can set its full modulepath in environment.conf with the
modulepath setting. The default value is that environment’s
modules directory followed by the base modulepath.
puppet apply on the command line, you also have the option of directly setting the modulepath with the
modulepath setting can only be set in environment.conf. It configures the entire modulepath for that environment.
The default value of
Note that the modulepath can include relative paths, such as
./site. Puppet looks for these paths inside the environment’s directory.
If you want an environment to have access to the global module directories, it should include
The base modulepath
The base modulepath is a list of global module directories for use with all environments. It can be configured with the
basemodulepath setting, but its default value is probably suitable for you unless you’re doing something unusual.
The default value of the
basemodulepath setting is
$codedir/modules:/opt/puppetlabs/puppet/modules. (On Windows, it will just use
puppet apply, you can supply a full modulepath as a command line option. This overrides the modulepath from the current environment.
Loading content from modules
Puppet uses modules from every directory in the modulepath.
Empty and absent directories
Directories in the modulepath can be empty, and might even be absent. In both cases, this is not an error; it just means Puppet does not load modules from those directories.
If no modules are present across the entire modulepath, or if modules are present but none of them contains a
lib directory, then Puppet agent will log an error when attempting to sync plugins from the Puppet master. This error is benign and will not prevent the rest of the Puppet run.
Duplicate or conflicting modules and content
If the modulepath contains multiple modules with the same name, Puppet uses the version from the directory that comes earliest in the modulepath. This allows directories earlier in the modulepath to override later directories.
For most content, this earliest-module-wins behavior is on an all-or-nothing, per-module basis — all of the manifests, files, and templates in the winning version will be available for use, and *none of that content from any subsequent versions will be available. This behavior covers:
- Puppet code (from
- Files (from
- Templates (from
- External facts (from
- Ruby plugins synced to agent nodes (from
However, Puppet occasionally shows problematic behavior with Ruby plugins loaded directly from modules. This includes:
- Plugins used by the Puppet master (custom resource types, custom functions)
- Plugins used by
- Plugins that happen to be present in Puppet agent’s modulepath (which should generally be empty, but might not be when running Puppet agent on a node that is also a Puppet master server)
With these plugins, the earlier module still wins, but the plugins are handled on a per-file basis instead of per-module. This means that if a duplicate module in a later directory has additional plugin files that don’t exist in the winning module, those extra files will be loaded, and Puppet will use a mixture of files from the winning and duplicate modules.
The upshot is, if you refactor a module’s Ruby plugins and then maintain two versions of that module in your modulepath, it can sometimes result in weirdness.
This is essentially the same Ruby loading problem that environments have, as described elsewhere in this manual. It’s not intentional, but it’s not likely to get fixed soon, since it’s a byproduct of the way Ruby works and Puppet only has a limited amount of control over it.