Java attacher runs only in non-cloud environments

[stuartnelson3]

Motivation/summary

start the java attacher jar only when running in a non-cloud environment

Checklist

• Update CHANGELOG.asciidoc
• Documentation has been updated

How to test these changes

1. start apm-server with the java attacher config enabled and ELASTIC_AGENT_CLOUD set in the environment
2. verify the java attacher does not start
3. start apm-server with the java attacher config enabled and ELASTIC_AGENT_CLOUD NOT set in the environment
4. verify the java attacher does start

Related issues

requested in #5479
depends on #6593

[mergify]

This pull request does not have a backport label. Could you fix it @stuartnelson3? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-7.x is the label to automatically backport to the 7.x branch.
• backport-7./d is the label to automatically backport to the 7./d branch. /d is the digit

NOTE: backport-skip has been added to this pull request.

[apmmachine]

💚 Build Succeeded

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Build stats

• Start Time: 2021-11-16T14:06:50.684+0000

• Duration: 40 min 31 sec

• Commit: a4be324

Test stats 🧪

Test	Results
Failed	0
Passed	5610
Skipped	19
Total	5629

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[stuartnelson3]

/test

[stuartnelson3]

@felixbarny would you be able to test this? the docker container doesn't contain the java runtime so the attacher errors out, but either building a tarball or running make && make build/apm-agent-attach-cli-1.27.0-slim.jar && cp build/java-attacher.jar . should put the .jar in the correct place relative to the apm-server binary.

[felixbarny]

We have a dedicated task to test the attachment end-to-end: elastic/apm-agent-java#2196. I think it makes sense to start that after #4830 is closed.

Sub-tasks like these can tested and reviewed in isolation as good as possible. I think the testing phase can start in parallel with the UI implementation. After the UI is done, there'll be a second QA phase that tests fully end-to-end.

WDYT?

[stuartnelson3]

Sounds good to me, will merge once tests pass

[stuartnelson3]

/test

[marclop]

Verified with cdeec66:

{"log.level":"error","@timestamp":"2022-01-04T15:41:28.521+0800","log.logger":"beater","log.origin":{"file.name":"beater/beater.go","file.line":443},"message":"java attacher not supported in cloud environments","service.name":"apm-server","ecs.version":"1.6.0"}