add elasticsearch API key support

[colinsurprenant]

Related to elastic/logstash#11788
Fixes #908

• Add support for elasticsearch API key authentication using the api_key option
  • SSL must be enabled
  • Only one authentication method must be specified out of (user/password, cloud_auth and api_key)
• Related specs
• Manually tested against a cloud cluster

TODO

• Add docs /cc (@karenzone)
• Bump version

[karenzone]

Thanks for adding the docs. What you have here builds cleanly and renders correctly.

From the issue description: "Only one authentication method must be specified out of (user/password, cloud_auth and api_key)". That info would be nice to call out in the docs. I suggest adding an "Authentication" section on par with "Retry Policy," "DLQ policy," and "ILM" to surface this information, and also making a note in each option about the alternatives that are excluded.

I can take this on in a subsequent PR if you would like. Let's discuss.

[colinsurprenant]

Thanks @karenzone - I just pushed some docs updates, LMKWYT.

[karenzone]

Thanks for the docs change, Colin. Docs still build and render correctly, so LGTM.

[colinsurprenant]

@kares following our conversation about the logstash license checker, I refactored to call the plugin validation methods from within build_client which now enables https://github.com/elastic/logstash#11818

LMKWYT

[colinsurprenant]

@yaauie let me know if this looks good to you too plus if the requirement on explicit ssl => true seems reasonable (and defer solving the unreliable SSL auto-detection in another PR).

[yaauie]

LGTM 👍

[colinsurprenant]

v10.5.0 published. Thanks @yaauie @kares @karenzone for the reviews!

[AMITKHETAN]

Hi, Its fixed but I still need to pass both API_ID and API_KEY value as "<API_ID>:<API_KEY>

[colinsurprenant]

@AMITKHETAN can you please open an issue about this and explain your use-case and how & why you would prefer to pass the API_ID and API_KEY values? Thanks,