Fix updated_by_last_action value of monitor provider

[olivielpeau]

Replaces #168 (see discussion there for more context on this issue)

use_inline_resources is the way to go to ensure that updated_by_last_action is correct.

It makes the provider actions run in their own run context, so we need to redefine the datadog-agent service in each action.

The behavior of the provider is preserved, except that the datadog-agent service gets restarted every time a config file is updated (instead of only being restarted once) when multiple files are updated in the same run.

[miketheman]

@olivielpeau I'm not certain I follow. I think the desire is to have datadog-agent restart once, at the end of the run, if there are any services notifying it to do so - this appears to define extra resources with the same name (which causes the infamous resource cloning), and I'm not sure that's the correct behavior, since we can have multiple restarts per addition to the file.

I'm also not sure about the removal of the updated_by_last_action - that's something we'd likely have to test - can you conceive of a way to test that?

[olivielpeau]

@miketheman I agree that restarting the service multiple times per run is a big issue...

Given that the provider's actions are executed in their own run contexts, the only way that I see to notify the service in the main run context would be to remove the notifications in the provider and add:

notifies :restart, 'service[datadog-agent]', :delayed

to every datadog_monitor resource block. But that changes the scope of what the resource does.
Unless I'm missing something.

I'm not sure what we could test exactly on the updated_by_last_action. Basically its current value doesn't make much sense (for instance it's always false for the add action, even when the config file has been changed). But I'm not sure I understand what you mean by testing its removal.

We could definitely test the whole provider with chefspec though.

[miketheman]

Thanks @olivielpeau !