Docker integration should know when it's running in Fargate

[orion-fra]

Description

When running in Fargate the ECS integration is not calling "connect" so all metadata related to the host is lost. Docker integration is also sending metrics without agent entityId.

The result is that the metadata is not decorated and some attributes are lost:

• awsRegion
• ecsClusterName
• ecsClusterArn
• ecsLaunchType

Expected Behavior

NR Diag results

Steps to Reproduce

See initially filed tickets: https://newrelic.atlassian.net/browse/GTSE-4812
Aso solving: https://newrelic.atlassian.net/secure/RapidBoard.jspa?rapidView=1643&projectKey=GTSE&modal=detail&selectedIssue=GTSE-5145

Your Environment

Additional context

@jlegoff noticed the docker integration is using the same API used by the ECS integration and can detect if it is running inside Fargat

In case the Docker integration is running inside Fargate the integration will send those missing attributes as a metric attribute. For instance, the awsRegion is got from the ARN.

From @paologallinaharbur
We should check that all the metadata is there from the old sample
ODL, NEW

https://github.com/newrelic/nri-ecs/blob/e2b3668bb8b244eda85ce113abac3d2e41251834/internal/metadata/v3/v3.go#L165

https://github.com/newrelic/nri-docker/blob/master/src/docker.go#L47

impersonate - See comments in CoreINT-337