Remove empty string as default value for VerificationMode

[narph]

• Bug

What does this PR do?

Original issue elastic/elastic-agent#184
Elastic agent accepts empty string value for ssl.verification_mode (which is equivalent to full), however Endpoint is logging an error since it is not a supported option, but, it's also setting the verification mode to full, so verification modes match.

The PR is removing empty string as a default/supported verification mode option. Default mode will be full.

Why is it important?

Avoids conflicts with other stakeholders.

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in CHANGELOG.md

Related issues

• Relates Unable to read fleet.ssl options: Invalid TLS validation configuration - endpoint security integration elastic-agent#184

[elasticmachine]

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• Start Time: 2022-06-23T12:24:52.951+0000

• Duration: 62 min 51 sec

Test stats 🧪

Test	Results
Failed	0
Passed	716
Skipped	5
Total	721

🤖 GitHub comments

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[narph]

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[narph]

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[narph]

/test

[fearful-symmetry]

Changes look good to me, although I'm assuming the change itself won't involve any user-facing breaking changes(?)

[belimawr]

@narph, the PR looks great, but to be on the safe side, I'd like to see test case for when the verification_mode is set to an empty string, e.g: test parsing a YAML like this:

verification_mode: ""

[narph]

@narph, the PR looks great, but to be on the safe side, I'd like to see test case for when the verification_mode is set to an empty string, e.g: test parsing a YAML like this:

verification_mode: ""

I've added some tests for this, including one with the scenario you suggested above but I assume by default verification_mode is not added in the configuration file instead of having a empty string value. Correct me if I am wrong here.

[belimawr]

@narph, the PR looks great, but to be on the safe side, I'd like to see test case for when the verification_mode is set to an empty string, e.g: test parsing a YAML like this:

verification_mode: ""

I've added some tests for this, including one with the scenario you suggested above but I assume by default verification_mode is not added in the configuration file instead of having a empty string value. Correct me if I am wrong here.

Yes, you're right, but some agent policies ended up having verification_mode: "", so I wanted to be extra cautious here.

[belimawr]

Suggested change