Monitoring: only include X-Pack API params when appropriate

[ycombinator]

What does this PR do?

This PR fixes the Elasticsearch monitoring reporter in libbeat to only include the system_id and system_api_version query string parameters in Elasticsearch API requests IF the Beat is sending its monitoring data to the custom X-Pack Monitoring API endpoint (/_monitoring/bulk). Otherwise, these parameters are not included.

Why is it important?

A Beat can be configured to send its monitoring data to Elasticsearch in two ways:

• using the deprecated xpack.monitoring.* settings. This causes the Beat to talk to the custom X-Pack Monitoring API endpoint (/_monitoring/bulk). This endpoint expects the system_id and system_api_version query string parameters.
• using the monitoring.* settings. This causes the Beat to talk to the generic Bulk API endpoint (/_bulk). This endpoint does not expect the system_id or system_api_version query string parameters.

It turns out that, after the fix made in #18326, the Elasticsearch monitoring reporter in libbeat was always sending the system_id and system_api_version query string parameters, regardless of which way a Beat was sending its monitoring data to Elasticsearch. This PR fixes this issue.

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 added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc. Not sure we need a CHANGELOG entry as this bug was not exposed until 7.8.0 (via [Libbeat] Respect the parameters option defined in the ES output. #18326), which has not yet been released.

Related issues

• Fixes Unable to send monitoring data due to 400 error from Elasticsearch bulk API #18786.

[elasticmachine]

Pinging @elastic/integrations (Team:Integrations)

[elasticmachine]

💚 Build Succeeded

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Build stats

• Build Cause: [Pull request #18787 updated]

• Start Time: 2020-05-27T18:27:09.839+0000

• Duration: 76 min 37 sec

Test stats 🧪

Test	Results
Failed	0
Passed	9242
Skipped	1542
Total	10784

Steps errors

Expand to view the steps failures

• Name: Report to Codecov

  • Description: curl -sSLo codecov https://codecov.io/bash for i in auditbeat filebeat heartbeat libbeat metricbeat packetbeat winlogbeat journalbeat do FILE="${i}/build/coverage/full.cov" if [ -f "${FILE}" ]; then bash codecov -f "${FILE}" fi done

  • Duration: 1 min 27 sec

  • Start Time: 2020-05-27T19:05:03.619+0000

  • log

• Name: Make -C generator/_templates/metricbeat test

  • Description: make -C generator/_templates/metricbeat test

  • Duration: 7 min 2 sec

  • Start Time: 2020-05-27T19:25:43.282+0000

  • log

[ph]

LGTM