Register custom logger before it gets used

[shubham2892]

Summary

When ECS_LOGLEVEL is set in Agent config file, healthcheck outputs shows following error -- [Error] format error: unrecognized formatter at 1: EcsAgentLogfmt\n"

It's because when ECS_LOGLEVEL is set, logger tries to load EcsAgentLogFmt custom formatter before it is initiated.
EcsAgentLogFmt gets loaded here -- https://github.com/aws/amazon-ecs-agent/blob/master/agent/logger/log.go#L97 which is being called by SetLevel() here -- https://github.com/aws/amazon-ecs-agent/blob/master/agent/logger/log.go#L97.

Currently custom formatter is initiated here -- https://github.com/aws/amazon-ecs-agent/blob/master/agent/logger/log.go#L167

Moving the initiation of custom formatter before SetLevel ensure that the formatter is initiated before it is getting loaded.

Implementation details

Testing

Steps to reproduce the issue --

1. Set ECS_LOGLEVEL=debug in /etc/ecs/ecs.config on al2.
2. Restart agent
3. docker inspect <agent container id>. Health check shows error format error: unrecognized formatter at 1: EcsAgentLogfmt\n

After the change, the health check was passing with ECS_LOGLEVEL set and I could see logs getting generated as expected in Agent log directory.

Description for the changelog

Bug - Health check output shows error message when ECS_LOGLEVEL is set in Agent config file.

Licensing

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

[petderek]

You should fix your commit. The author is root.

[petderek]

Cool fix, though!