Set agent.name to hostname by default

[andrewkroh]

What does this PR do?

Since ECS does not define agent.hostname it will be removed in a future release.
In order to always have a field available to identify the agent by name we will
set the agent.name to hostname unless the user has provided a custom name.

Why is it important?

This puts the hostname into events by default. This will be important for cases where events may not contain the forwarding machine's hostname. For example when forwarding syslog data we may not have the host or observer namespaces populated.

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.

Related issues

Relates #16377

Logs

Event output when name is unset.

  "agent": {
    "name": "mac.example.com",
    "type": "filebeat",
    "version": "8.0.0",
    "hostname": "mac.example.com",
    "ephemeral_id": "a690e034-28ac-413b-8bad-b618b57a2d79",
    "id": "fb930b06-9125-40b5-902c-bf0b0f077592"
  },

Event when name: my_custom_name is set:

  "agent": {
    "type": "filebeat",
    "version": "8.0.0",
    "hostname": "mac.example.com",
    "ephemeral_id": "c421fd5a-613b-4c40-aaa3-128c7e84a47c",
    "id": "b7e68e5b-cc5b-43b3-9e6b-0e74d2abde4d",
    "name": "my_custom_name"
  }

[elasticmachine]

Pinging @elastic/siem (Team:SIEM)

[exekias]

should "name" also be here?

[exekias]

nevermind, I see this has not changed

[andrewkroh]

Correct, I didn't change observer. I had to separate them to avoid introducing changes to it. observer does need some changes, but that's another task - probably for 8.0.

[elasticmachine]

💚 Build Succeeded

Expand to view the summary

Build stats

• Build Cause: [andrewkroh commented: run tests]

• Start Time: 2020-05-02T02:53:47.881+0000

• Duration: 85 min 25 sec (5125116)

• Commit: db5eb1c

Test stats 🧪

Test	Results
Failed	0
Passed	7688
Skipped	1210
Total	8898

Steps errors

Expand to view the steps failures

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

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

  • Result: FAILURE

  • Duration: 2 min 38 sec<

  • Start Time: 2020-05-02T03:24:58.364+0000

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

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

  • Result: FAILURE

  • Duration: 1 min 50 sec<

  • Start Time: 2020-05-02T03:27:26.755+0000

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

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

  • Result: FAILURE

  • Duration: 1 min 24 sec<

  • Start Time: 2020-05-02T03:29:54.114+0000

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

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

  • Result: FAILURE

  • Duration: 6 min 14 sec<

  • Start Time: 2020-05-02T03:39:45.712+0000

• 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

  • Result: FAILURE

  • Duration: 1 min 27 sec<

  • Start Time: 2020-05-02T03:46:02.118+0000

[andrewkroh]

run tests