Add AWS Secret manager integration to Container Definition

[luiseterc]

This PR enables a Elastic Profile agent configuration to integrate with the AWS Secrets Manager by adding three new fields to the profile template:

• Secret name: The environment variable where the Secret value will be assigned to and accesible from the ECS task
• Secret value (valueFrom): The secret to expose to the container. The supported values are either the full ARN of the AWS Secrets Manager secret or the full ARN of the parameter in the AWS Systems Manager Parameter Store.
• Execution Role ARN: The Amazon Resource Name (ARN) of the task execution role that grants the Amazon ECS container agent permission to make AWS API calls on your behalf.

If all these variables are set and not blank, the following JSON key is added to the ContainerDefinition:

{ "containerDefinitions": [{ "secrets": [{ "name": "environment_variable_name", "valueFrom": "arn:aws:secretsmanager:region:aws_account_id:secret:secret_name-AbCdEf" }] }] }

So far only the "referencing a full secret" use case is implemented as described in https://docs.aws.amazon.com/AmazonECS/latest/developerguide/specifying-sensitive-data-secrets.html. Some work still needed to support other use cases such as referencing a specific key within a secret.

Tested successfully on a real production GoCD environment.

[gocd-cla-bot]

All committers have signed the CLA.

[luiseterc]

Any plans to merge this PR or is that already supported on most recent versions?

[chadlwilson]

Unfortunately there are few folks in a position to review PRs right now, or in a position to test/validate them and make a call on whether they make sense for the plugins.

Personally, I'm not quite sure what the role of this is, compared to https://github.com/gocd/gocd-aws-based-secrets-plugin - what does this allow you to achieve which you can't do by allowing the GoCD server to retrieve secrets and distribute them to relevant build jobs running on an agent on your behalf? Is it just an alternative which doesn't involve the server needing direct access to secrets?