Localstack ECS Environment Variable Bug

Environment variables don't appear to be propagated into ECS containers in Localstack.

Reproduction Steps

1. Build Container

make

This container basically just runs env to output the environment it is operating in.

2. Bring up Localstack

export LOCALSTACK_API_KEY=XXXXX
docker-compose up

Make sure to supply a valid Localstack Pro API key.

3. Run Pulumi

cd pulumi
pulumi login --local
export PULUMI_CONFIG_PASSPHRASE=test
pulumi stack init dev
pulumi up

This will create a minimal infrastructure including an ECS service running the container we built earlier.

4. Check Container

docker logs -f localstack_testing-family_1

You should see the following values in the environment being printed out, along with other standard values:

FOO=BAR
MESSAGE=HELLO WORLD