Motivation

As announced in #11803, with LocalStack 4.0 we are deprecating the usage of non-prefixed environment variables in the CLI:

The LocalStack CLI is closely integrated with the runtime and needs to be able to determine which environment variables it should pass from the user's environment to the Docker container. This requirement restricts the CLI’s compatibility with new environment variables introduced in later LocalStack versions, often leading to issues that are challenging to debug. Using a well-known prefix (LOCALSTACK_) will enable forwards-compatibility for newer configuration options. To enhance flexibility, users are encouraged to use a variable prefix (LOCALSTACK_) for more straightforward management of environment variables across different versions.

This PR adds a deprecation warning to inform users about this change.

Changes

• Add a warning if a non-prefixed environment variable is loaded to be forwarded to the runtime container.
• Loads the env var "LOG" if "LS_LOG" is not present to allow setting "LOCALSTACK_LOG" instead of "LOCALSTACK_LS_LOG" in Docker mode.

TODO

• Add prefix for environment variables defined in a profile.
• Check where the best place to show the warning is.
  • Unfortunately, the place for the warning right now isn't the best, but we can properly separate this in upcoming iterations.