Secrets with docker-compose

create-secret.sh

echo "This is a secret" | docker secret create my_secret_data -

docker-compose.yml

---
version: '3'

services:
  someapp:
    image: python:3.6
    command: python3 -m http.server
    deploy:
      replicas: 1
      placement:
        constraints:
          - node.role == manager
    secrets:
      - source: my_secret_data
    environment:
      - MY_SECRET_DATA_FILE: /run/secrets/my_secret_data

secrets:
  my_secret_data:
    external: true

read-environment-variable.py

os.environ.get('MY_SECRET_DATA') \
  or open(os.environ.get('MY_SECRET_DATA_FILE')).read()
>> 'This is a secret\n'

# or read them all:

[{f: open('/run/secrets/{}'.format(f)).read().rstrip()} for f in os.listdir('/run/secrets')]
>> [{'foo': 'bar'}, {'my_secret_data': 'This is a secret'}]