[Manual backport][Heartbeat] Unpack beats in elastic-agent docker image

[emilioalvap]

Manual backport of elastic/elastic-agent#202

What does this PR do?

This PR enables unpacking of beats inside the container at build time, so that required cap_net_raw, cap_setuid capabilities can be assigned to the binary.

Why is it important?

Without the required capabilities, heartbeat cannot execute ICMP pings or setuid calls. As it is now, agent is unpacking beats at runtime, most likely with a user that doesn't have permission to assign capabilities.

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

Author's Checklist

• [ ]

How to test this PR locally

• Build elastic-agent containers, run:
  DEV=true SNAPSHOT=true PLATFORMS=linux/amd64 TYPES=docker mage package
• Run one of the built containers and provide some heartbeat configuration:

docker run --name agent -it -u root --env FLEET_ENROLL=1 --env \
FLEET_URL=<url> --env \ 
FLEET_ENROLLMENT_TOKEN=<token> \ 
docker.elastic.co/beats/elastic-agent:8.2.0-SNAPSHOT

Related issues

• Relates [elastic-agent][heartbeat] Heartbeat binary should have setcap privs for ICMP ping #27651

Screenshots

Logs

15:38:37.323
elastic_agent.heartbeat
[elastic_agent.heartbeat][info] heartbeat start running.
15:38:37.323
elastic_agent.heartbeat
[elastic_agent.heartbeat][warn] BETA: Fleet management is enabled
15:38:37.323
elastic_agent.heartbeat
[elastic_agent.heartbeat][info] Starting fleet management service
15:38:37.323
elastic_agent.heartbeat
[elastic_agent.heartbeat][info] heartbeat is running! Hit CTRL-C to stop it.
15:38:37.323
elastic_agent.heartbeat
[elastic_agent.heartbeat][info] Effective user/group ids: 1000/1000, with groups: [0]

[elasticmachine]

Pinging @elastic/elastic-agent (Team:Elastic-Agent)

[elasticmachine]

Pinging @elastic/uptime (Team:Uptime)

[elasticmachine]

💚 Build Succeeded

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Build stats

• Start Time: 2022-03-24T10:06:05.934+0000

• Duration: 182 min 46 sec

Test stats 🧪

Test	Results
Failed	0
Passed	25667
Skipped	2192
Total	27859

💚 Flaky test report

Tests succeeded.

🤖 GitHub comments

To re-run your PR in the CI, just comment with:

• /test : Re-trigger the build.

• /package : Generate the packages and run the E2E tests.

• /beats-tester : Run the installation tests with beats-tester.

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[emilioalvap]

/test

[andrewvc]

@Mergifyio update

[mergify]

update

✅ Branch has been successfully updated

[elasticmachine]

Pinging @elastic/elastic-agent-control-plane (Team:Elastic-Agent-Control-Plane)

[emilioalvap]

@Mergifyio update

[mergify]

update

✅ Branch has been successfully updated

[emilioalvap]

Hi @elastic/beats, could someone provide a review for this PR? Thanks!

[cmacknz]

LGTM, you should be good with just the approval from the agent control plane team (which Michel has provided).