Adds support for Grafana Loki docker log driver.

[cyriltovena]

Hello this adds support for the Grafana Loki driver in the ecs agent.

Let me know if there is anything else I need to do.

Signed-off-by: Cyril Tovena cyril.tovena@gmail.com

[cyastella]

thanks for submitting this, we will look into it. I am updating the target branch for this pull request from aws:master to aws:dev to point to the working branch =)

[yhlee-aws]

Thank you for the PR. We've investigated and looks like customers can use FireLens to route logs to Grafana Loki, see the Fluent Bit output plugin contributed here. Therefore we've decided against adding explicit support for it in ECS Agent at this time.

[yhlee-aws]

FYI we have an open feature request for supporting custom log driver here, which should enable customers to use Grafana Loki driver.