Disable sourcemap upload endpoint when data streams enabled

[jalvz]

Motivation/summary

If we don't do this, users will see a 202 - Accepted response, but apm-server will fail to index sourcemaps due to lack of permissions.

Checklist

• Update CHANGELOG.asciidoc

How to test these changes

Run apm-server with data streams enabled and send a POST request to http://localhost:8200/assets/v1/sourcemaps.
The request should fail.

[axw]

Nice catch.

Just one thing with the error message. Generally I'd like to minimise cognitive overhead for users by tailoring the error message to the running configuration.

[axw]

We know whether or not APM Server is managed by Fleet - can we change the error message based on that knowledge? Saves the user trying to figure out whether source maps are explicitly disabled, or implicitly because data streams are enabled.

[jalvz]

I was just being lazy... you got me

[apmmachine]

💚 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 #4735 updated

• Start Time: 2021-02-16T11:03:20.760+0000

• Duration: 55 min 25 sec

• Commit: 5b837b5

Test stats 🧪

Test	Results
Failed	0
Passed	4751
Skipped	124
Total	4875

Trends 🧪

Steps errors

Expand to view the steps failures

Run Window tests

• Took 11 min 41 sec . View more details on here

Compress

• Took 0 min 0 sec . View more details on here
• Description: tar --exclude=coverage-files.tgz -czf coverage-files.tgz coverage

Compress

• Took 0 min 0 sec . View more details on here
• Description: tar --exclude=system-tests-linux-files.tgz -czf system-tests-linux-files.tgz system-tests

Test Sync

• Took 4 min 4 sec . View more details on here
• Description: ./.ci/scripts/sync.sh

[axw]

Thanks :)

[axw]

Confirmed with BC2:

$ curl http://localhost:8200/assets/v1/sourcemaps -F sourcemap=@app.e2e-bundle.min.js.map -F bundle_filepath=/index.js -F service_name=service_name -F service_version=123
{
  "error": "forbidden request: When APM Server is managed by Fleet, Sourcemaps must be uploaded directly to Elasticsearch."
}

[axw]

Also confirmed that the old message is returned from a standalone APM Server when RUM is disabled:

{
  "error": "forbidden request: Sourcemap upload endpoint is disabled. Configure the `apm-server.rum` section in apm-server.yml to enable sourcemap uploads. If you are not using the RUM agent, you can safely ignore this error."
}