Expected Behavior

When using the env_file attribute in docker-compose.yml to load environment variables:

1. Default value syntax (e.g., ${VAR:-default}) in the .env file should be parsed and resolved correctly.

• Example: DOC_ENGINE=${DOC_ENGINE:-elasticsearch} should resolve to DOC_ENGINE=elasticsearch if the variable is unset.

2. The generated ConfigMap (from the .env file) should contain resolved values, not raw expressions.
3. References between variables in .env (e.g., COMPOSE_PROFILES=${DOC_ENGINE}) should inherit the resolved value.

Actual Behavior

Kompose does not parse default value syntax in .env files. Instead:

1. The generated ConfigMap contains malformed values (e.g., :-elasticsearch}), indicating a failure to resolve ${VAR:-default}.
   Example:

apiVersion: v1
data:
  DOC_ENGINE: :-elasticsearch}  # Invalid syntax
  COMPOSE_PROFILES: :-elasticsearch}
kind: ConfigMap
metadata:
  labels:
    io.kompose.service: minio-env
  name: env

2. Variables referencing unresolved values (e.g., COMPOSE_PROFILES=${DOC_ENGINE}) inherit the malformed syntax, breaking dependent configurations.

Steps To Reproduce

1. Create docker-compose.yml:

version: '3'
services:
  minio:
    image: quay.io/minio/minio:latest
    env_file: .env  # Load variables from .env
    ports:
      - 9000:9000
 

2. Create .env file with:

DOC_ENGINE=${DOC_ENGINE:-elasticsearch}
COMPOSE_PROFILES=${DOC_ENGINE}  # Reference the variable with default

3. Run:
   kompose -f docker-compose.yml convert -c

Kompose Version

1.35.0

Docker-Compose file

version: '3'
services:
  minio:
    image: quay.io/minio/minio:latest
    env_file: .env  # Load variables from .env
    ports:
      - 9000:9000

Anything else?

No response