Dockerfile does not allow use of environment variables

[agalazis]

Describe the bug

You cannot state environment variables in aws commands

Expected Behavior

I should be able to use ["s3" , "cp", "${SOURCE}", "${DESTINATION}" ] for exampled where SOURCE and DESTINATION are environment variables

Current Behavior

"${SOURCE}" and "${DESTINATION}" are taken literally as the strings "${SOURCE}" and "${DESTINATION}"

Reproduction Steps

Make an image that USES environment variables in CMD

Possible Solution

After reading about a ancient docker issue., I was able to get environment variables to work by overwriting the entrypoint to a file that contains the following 2 lines:

#!/bin/bash
bash -c "aws $*"

Additional Information/Context

Related docker issue
moby/moby#5509

CLI version used

2

Environment details (OS name and version, etc.)

Linux

[tim-finnigan]

Hi @agalazis thanks for reaching out. I think this is just a limitation of Docker — here is an explanation.

If you want to pass environment variables you can use the -e flag, for example:

docker run -e SOURCE_BUCKET -e DEST_BUCKET amazon/aws-cli s3 cp s3://$SOURCE_BUCKET/test.txt s3://$DEST_BUCKET/test.txt

Here are more examples in the AWS CLI documentation: https://docs.aws.amazon.com/cli/latest/userguide/getting-started-docker.html#cliv2-docker-share-files

You can also use sh as the ENTRYPOINT:

FROM amazon/aws-cli:latest
ENV TARGET_BUCKET='bucket-name'
ENTRYPOINT [ "sh", "-c", "aws s3 ls s3://$TARGET_BUCKET" ]

[agalazis]

yes that's what I proposed as the default entry point but then when I thought of it it might be a breaking change since people might rely on existing escaping so you can close this ticket. I guess the best option is to extend the base image.
In my case I run fargate tasks and overwriting entrypoint in containerOverrides is not an option... otherwise I wouldn't even need to maintain our own image just for the entrypoint change.

[agalazis]

This might cause a breaking change so closing...

[github-actions]

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