Make docker health check configurable

[richardpen]

Summary

Fix #1235 Add an environment variable to disable the container health check.

Implementation details

Testing

• Builds on Linux (make release)
• Builds on Windows (go build -out amazon-ecs-agent.exe ./agent)
• Unit tests on Linux (make test) pass
• Unit tests on Windows (go test -timeout=25s ./agent/...) pass
• Integration tests on Linux (make run-integ-tests) pass
• Integration tests on Windows (.\scripts\run-integ-tests.ps1) pass
• Functional tests on Linux (make run-functional-tests) pass
• Functional tests on Windows (.\scripts\run-functional-tests.ps1) pass

New tests cover the changes:

Description for the changelog

Licensing

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[samuelkarp]

Rather than disabling the health check feature, why not add heartbeat messages like we do for the ACS websocket?

[adnxn]

Rather than disabling the health check feature, why not add heartbeat messages like we do for the ACS websocket?

Why would those two be equivalent changes? I don't follow.

[samuelkarp]

Reading #1235 (comment), it looks like the underlying issue is the websocket being closed because there is no traffic over it:

Yes, those errors are caused by the fact that there is no activity in the connection. And this connection is used to publish resource usage metrics and container health metrics. So, if the ECS_DISABLE_METRICS=true is set and no containers are using the container health check feature, the connection will be closed periodically.

Rather than turning off a useful feature (health check support), it would make more sense to me to address the websocket inactivity issue.

[rhuddleston]

any update on this? Our logs get spammed with "Error getting message from ws backend" after setting ECS_DISABLE_MTERICS=true

[adnxn]

closing in favor of #1624