fix: use proper format for kibana's server host

[mdelapenya]

What does this PR do?

It uses a proper format for the value of kibana's server host, matching that value with other maintenance branches (master, 7.13, 7.12, 7.11)

Why is it important?

Kibana cannot start, therefore the runtime dependencies for the tests are not satisfied, causing the entire test suite to fail.

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have run the Unit tests for the CLI, and they are passing locally
• I have run the End-2-End tests for the suite I'm working on, and they are passing locally
• I have noticed new Go dependencies (run make notice in the proper directory)

Author's Checklist

• Kibana seems to prevent the '0' value, although I checked its docs and it's not updated: https://github.com/elastic/kibana/blame/7.x/docs/setup/docker.asciidoc#L146. Will check Kibana's git history for 7.x to bisect when/where that change was introduced and to update the docs.

Related issues

• Fixes [7.x] Kibana is not able to start #1194

[elasticmachine]

💚 Build Succeeded

the below badges are clickable and redirect to their specific view in the CI or DOCS

Expand to view the summary

Build stats

• Build Cause: Pull request #1195 opened

• Start Time: 2021-05-24T09:10:27.955+0000

• Duration: 23 min 34 sec

• Commit: 24513cd

Test stats 🧪

Test	Results
Failed	0
Passed	160
Skipped	0
Total	160

Trends 🧪

💚 Flaky test report

Tests succeeded.

Expand to view the summary

Test stats 🧪

Test	Results
Failed	0
Passed	160
Skipped	0
Total	160

[mdelapenya]

@watson are you aware of a change in 7.x about this issue? I remember a warning was added in elastic/kibana#87471, but since friday, the 7.x kibana build is not able to start because of the server host issue. Please see log error in #1194. I'd appreciate if you are able to point me to the possible change, as I haven't been able to find it yet.

[watson]

Hmm 7.x should still support using 0 as the server.host, just outputting a deprecation warning. Support for using just 0 seems to have been removed in elastic/kibana#100378. Last time this was discussed this was considered a breaking change, so I assume it's accidental. ping @elastic/kibana-core

[watson]

I've created a PR to fix this: elastic/kibana#100551 - hopefully the tests pass and core agrees this is the way to go.

[mdelapenya]

Thanks! We will revert this commit to represent the current state of 7.x in Kibana.

[pgayvallet]

Support for using just 0 seems to have been removed in elastic/kibana#100378.

Not sure how I did mess up that backport, but that was a mistake, yes. 0 should still be supported on 7.x. Thanks for elastic/kibana#100551.

[watson]

@mdelapenya I've merged the fix into 7.x now. Thanks for spotting this 👍