Adding support for list of datadog tags in v6 configuration file

[skarlupka]

Fixes #556

[tschroeder-zendesk]

Any estimate on when this might get merged?

[remeh]

Hey @skarlupka , thank you for your contribution!
I've investigated this and indeed we have a different behavior between the Agent 5 and Agent 6 while using a list of tags.

Before merging your pull-request I would like to add some commits to have the exact same behavior between Agent 5 and Agent 6 (the list of tags injected in the Agent 5 configuration is working but not 100% correct).

Could I ask you to tick the box letting me to push commits in your PR? Thank you.
Edit: don't mind the last sentence, it looks like I can already push to your branch.

[skarlupka]

Hello @remeh!

The "Allow edits from maintainers" is checked in the PR. Let me know if there is anything else I need to do.

[remeh]

Thank you @skarlupka

I've added a condition to correctly handle array of tags in the Agent 5 configuration + I've slighty changed your PR to stay with respond_to tests to be consistent with the rest of the repo.

[olivielpeau]

LGTM 👍

Could you also update the attribute documentation here?

chef-datadog/attributes/default.rb

Lines 96 to 101 in 45e0097

	# This can be a string of comma separated tags or a hash in this format:
	# default['datadog']['tags'] = { 'datacenter' => 'us-east' }
	# Thie above outputs a string: 'datacenter:us-east'
	# When using the Datadog Chef Handler, tags are set on the node with preset prefixes:
	# `env:node.chef_environment`, `role:node.node.run_list.role`, `tag:somecheftag`
	default['datadog']['tags'] = ''

As we discussed offline a list on node['datadog']['tags'] wasn't supported officially by the cookbook, but did work on Agent 5, even though it wasn't by design: the INI format of Agent 5 doesn't support non-scalar values like lists, so for a config like:

tags: ["foo:bar", "bar:baz"]

Agent 5 sends the tags ["foo:bar" and "bar:baz"], but the Datadog backend then cleans up the characters that aren't allowed in tags so that foo:bar and bar:baz are indeed applied as tags to the host.

[remeh]

Thanks again for your contribution @skarlupka!

@tschroeder-zendesk I'm merging this to master now and it'll be part of release 2.17.0