Configuration file to map AWS Profiles with particular registries

[callumcrossley12]

Issue #, if available: #249

Description of changes:

The primary change is to add a new registryConfig file to map specific registries to use specific AWS_PROFILES. In general this is useful for environments where different profiles are used across accounts (i.e. for different AWS registries or permissions). I investigated using workarounds like credential wrappers but figured it may be more appropriate (particularly for us Windows users) to implement it in the tool.

The general flow is:

1. Try to fetch the registryConfig file from disk
2. If it exists, try to fetch the profile for a specific registry with pattern
3. If profile is provided and is valid, use it for getting the auth token

If the file doesn't exist or the registry isn't mapped, it will fallback to using the default AWS configuration flow.

The file is simply a mapping of registries patterns to profiles. This could be extended in the future to include additional registry configuration if needed. Example file:

registryConfigs:
  - registry: "123456789000.dkr.ecr.ap-southeast-2.amazonaws.com"
    config:
      profile: "some_profile"
  - registry: "987654321000.dkr.ecr.us-east-1.amazonaws.com"
    config:
      profile: "another_profile"
  - registry: "*.us-east-1.amazonaws.com"
    config:
      profile: "fallback_profile"

I've also added some minor changes to make Windows development a bit more friendly:

• Ensure .sh files use LF line endings
• Add .vscode to the .gitignore

This is both my first time raising a PR for an Opensource project and working with Go so feedback is appreciated.

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

[callumcrossley12]

It may be overkill to try fetch the config file each time. I could potentially introduce a new env var (e.g. AWS_ECR_USE_REGISTRY_CONFIG) to determine whether to fetch in the first place?

[callumcrossley12]

Is there a scenario where we want to explicit use an explicit profile for Fips endpoints?

[dougbyrne]

This could lead to some unexpected behavior. I would expect that the program proceed as if there is no config file in this case. Happy to be told that this is customary and expected though.

[callumcrossley12]

Agreed. I've updated it to have the same fallback behaviour as other parts of the code (i.e. to ~/.ecr)

[dougbyrne]

Do prefix wildcards work here? I usually have one profile per account ID, but it would be shared across all regions.

[callumcrossley12]

A good idea, I've added support for both prefix and suffix wildcards