Puppet : How to execute a single class? - puppet

Question

I use Puppet in a master -> agent model. My manifests are stored on the master and as a quick test I execute puppet agent -t on my agent to trigger a Puppet run.
Over time, my manifests have grown quite large and I am looking for the ability to only execute a single class say mycompany.someclass.class
I have attempted a number of variations based on google searches but none have worked
puppet agent --tags mycompany.someclass.class
puppet agent --tags "mycompany.someclass.class"
puppet agent --tags Mycompany.Someclass.Class
puppet agent -t --tags "Mycompany.Someclass.Class"
puppet agent -t --tags Mycompany.Someclass.Class
puppet agent --tags Mycompany.Someclass.Class
puppet apply --tags mycompany.someclass.class
puppet apply --tags Mycompany.Someclass.Class

Answer 1

You can execute a subset of resources with the --tags argument just like you mention in the question. However, you first have to set the associated tag in the resources you want executed for that tag. If you wanted to execute only one class, then you can set a tag for that class and specify that tag as the argument to --tags to execute only that class.
https://docs.puppet.com/puppet/4.10/lang_tags.html
In this case, the tag function will be much more useful for you than the metaparameter.
https://docs.puppet.com/puppet/4.10/lang_tags.html#the-tag-function
# You can use the tag function inside a class definition or defined type to assign tags to the surrounding container and all of the resources it contains
class myClass {
tag 'mytag'
...
}
You can then execute only myClass:
# execute agent with tags
puppet agent -t --tags mytag
https://docs.puppet.com/puppet/4.10/lang_tags.html#restricting-catalog-runs

Answer 2

You can also run the agent using the class name as a tag, if you don't feel like tagging all your resources.
CAVEAT FOR THE UNINITIATED: This is not a get-out-of-jail-free card ALL classes for the node in question must still compile cleanly, even though you are only applying some of them.