[Fleet] Exclude Synthetics from per-policy-outputs

[jillguyonnet]

Summary

Closes #155725

Context

Basic license users cannot use Synthetics private locations and a default Logstash output (cf. this comment). This is because under Basic license per policy output is not allowed.

There was a similar issue with Fleet server that was fixed by adding logic to exclude the fleet server integration from the checks (PR).

This PR follows a very similar approach for the synthetics integration.

Changes

Compare these to the corresponding changes that were made for Fleet server.

• If the user tries to change the default output from ES to Logstash and there are agent policies using synthetics, then an error is thrown.
• If an existing Logstash output is made to be the default output and there are agent policies using synthetics, then these policies will still be using the previous default ES output.
• If the default output is of type Logstash with an agent policy using synthetics and another ES output, then if the user tries to delete the ES output an error is thrown.
• Logstash type outputs are disabled in the agent policy settings if the policy uses synthetics.

Steps for testing

⚠️ Ideally the complete scenario reported here should be tested. I was having some issues running a dev setup with a proper Logstash output, so the steps below are not end-to-end (similar to #153226).

1. Start with a single default ES output, an agent policy (1) with synthetics and another (2) without (NB: you can also test combinations with fleet server; if an error is thrown, the error for fleet server would be thrown before the one for synthetics).
2. Edit the default ES output to be a Logstash output; this should fail and thrown the following error:
   
3. Create a new Logstash output and make it default on creation. Go the agent policies and check the policies settings: the Output for integrations setting should still be set to the previous ES default output for policies with synthetics (and/or fleet server), and should have switched to the new Logstash default for other policies.
4. Repeat the previous steps, but this time first create the Logstash output and then edit it to make it default. This tests the update behaviour as opposed to create. You will see the following warning:
   
5. Still with the default Logstash output, try to delete the ES output (that is still used by policies with synthetics/fleet server(. This should fail with the following error:
   
6. (Basic license constraint) Create another ES output (not default). Go the agent policies and check the policies settings: policies with synthetics (or fleet server) should be allowed to switch the Output for integrations setting to the new ES output:
   
   In contrast, policies without these integrations should be constrained to the default Logstash output:
   

Checklist

• Documentation was added for features that require explanation or tutorials
• Unit or functional tests were updated or added to match the most common scenarios

[apmmachine]

🤖 GitHub comments

Expand to view the GitHub comments

Just comment with:

• /oblt-deploy : Deploy a Kibana instance using the Observability test environments.
• run elasticsearch-ci/docs : Re-trigger the docs validation. (use unformatted text in the comment!)

[elasticmachine]

Pinging @elastic/fleet (Team:Fleet)

[jillguyonnet]

@elasticmachine merge upstream

[kibana-ci]

💚 Build Succeeded

• Buildkite Build
• Commit: 4460a2d

Metrics [docs]

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
fleet	981.2KB	981.2KB	+62.0B

Page load bundle

Size of the bundles that are downloaded on every page load. Target size is below 100kb

id	before	after	diff
fleet	134.3KB	134.6KB	+304.0B

History

• 💛 Build #142532 was flaky fc6905b
• 💔 Build #142501 failed ab734c1

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

cc @jillguyonnet

[juliaElastic]

LGTM, thanks for the tests

[criamico]

LGTM! 🚢