health-report: link to major.minor-versioned help docs on 9.0+

[yaauie]

Release notes

• fixed an issue where a diagnosis in the health report on Logstash 9.0.0 points to future-facing documentation (master) instead of the docs that are specific to 9.0 (9.0)

What does this PR do?

• determines the help URL base at compile-time based on a few factors:
  • snapshot builds for unreleased branches:
    • 9.x points to master
    • others point to ${majorVersion}.x
  • others point to ${majorVersion}.${minorVersion}

Why is it important/What is the impact to the user?

When running Logstash 9.0, this makes the help_url-s in diagnostics correctly point to 9.0-specific guidance, instead of pointing to forward-facing guidance from the bleeding edge of main/master.

As of the time of this writing, the two are the same; but as new things are added to main, they will eventually diverge.

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 (and/or docker env variables)
• [ ] I have added tests that prove my fix is effective or that my feature works

How to test this PR locally

The procedure is the same in several configurations

1. start a pipeline that will block

   bin/logstash -e 'input { generator { } } filter { ruby { code => "sleep 1" } } output { sink { } }'
   

2. watch the health report for ~1 minute until the status degrades:

   watch curl --silent 'localhost:9600/_health_report?pretty=true'
   

Configurations:

• snapshots:
  • unrelased main:
    • ensure versions.yml is unmodified: git checkout -- versions.yml
    • build logstash ./gradlew installDefaultGems --info | grep HelpUrl
    • run test
    • expect url to begin with https://www.elastic.co/guide/en/logstash/master/
  • unreleased 8.19
    • emulate versions: yq -i '(.logstash, ."logstash-core") = "8.19.0"' versions.yml
    • build logstash ./gradlew installDefaultGems --info | grep HelpUrl
    • run test
    • expect url to begin with https://www.elastic.co/guide/en/logstash/8.x/
  • 9.0 branch
    • emulate versions: yq -i '(.logstash, ."logstash-core") = "9.0.1"' versions.yml
    • build logstash ./gradlew installDefaultGems --info | grep HelpUrl
    • run test
    • expect url to begin with https://www.elastic.co/guide/en/logstash/9.0/
• releases:
  • main (suppose 9.1 release):
    • emulate versions: yq -i '(.logstash, ."logstash-core") = "9.1.0"' versions.yml
    • build logstash RELEASE=1 ./gradlew installDefaultGems --info | grep HelpUrl
    • run test
    • expect url to begin with https://www.elastic.co/guide/en/logstash/9.1/
  • unreleased 8.19
    • emulate versions: yq -i '(.logstash, ."logstash-core") = "8.19.0"' versions.yml
    • build logstash RELEASE=1 ./gradlew installDefaultGems --info | grep HelpUrl
    • run test
    • expect url to begin with https://www.elastic.co/guide/en/logstash/8.19/
  • 9.0 branch
    • emulate versions: yq -i '(.logstash, ."logstash-core") = "9.0.1"' versions.yml
    • build logstash RELEASE=1 ./gradlew installDefaultGems --info | grep HelpUrl
    • run test
    • expect url to begin with https://www.elastic.co/guide/en/logstash/9.0/

[mergify]

This pull request does not have a backport label. Could you fix it @yaauie? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-8./d is the label to automatically backport to the 8./d branch. /d is the digit.
• If no backport is necessary, please add the backport-skip label

[elastic-sonarqube]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarQube

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: 0a2ae1f

History

• 💔 Build #2924 failed f37f304

[mashhurs]

LGTM!