Como Parametrizar o Compose com Variáveis de Ambiente

~/devops-kube-news$ vim compose.yaml

As variáveis são definidas com ${}:

services:
  postgre:
    image: postgres:${POSTGRES_TAG}
    ports:
      - 5432:5432
    environment:
      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD}
      POSTGRES_USER: ${POSTGRES_USER}
      POSTGRES_DB: ${POSTGRES_DB}
    volumes:
      - postgre-docker-vol:/var/lib/postgresql/data
    networks:
      - kubenews-net
  kubenews:
    image: marcelodpbarbieri/kube-news:${KUBENEWS_TAG}
    build:
      context: ./src
      dockerfile: Dockerfile
    ports:
      - 8080:8080
    depends_on:
      - postgre
    environment:
      DB_DATABASE: ${POSTGRES_DB}
      DB_USERNAME: ${POSTGRES_USER}
      DB_PASSWORD: ${POSTGRES_PASSWORD}
      DB_HOST: postgre
    networks:
      - kubenews-net

volumes:
  postgre-docker-vol:

networks:
  kubenews-net:
    driver: bridge

Maneiras de Passar os Valores

Existem duas formas de passar os valores para as variáveis:

Comando de subida do Docker Compose

~/devops-kube-news$ POSTGRES_TAG=12.17 \ 
                    POSTGRES_PASSWORD=kubenews \ 
                    POSTGRES_USER=kubenews \
                    POSTGRES_DB=kubenews \
                    KUBENEWS_TAG=v2 \
                    docker compose up -d
[+] Running 15/15
 ✔ postgre Pulled                                                           16.7s
   ✔ c57ee5000d61 Pull complete                                              6.5s
   ✔ 488633c8ea56 Pull complete                                              6.5s
   ✔ b225155ec9af Pull complete                                              6.7s
   ✔ 3ac67b1cae65 Pull complete                                              6.7s
   ✔ d61f871f8508 Pull complete                                              7.0s
   ✔ 54b907a1ec71 Pull complete                                              7.1s
   ✔ a237b518eb0c Pull complete                                              7.1s
   ✔ 84e65f02e2ea Pull complete                                              7.2s
   ✔ 719de8b4249b Pull complete                                             12.7s
   ✔ a92b8318c401 Pull complete                                             12.7s
   ✔ a919920e6eed Pull complete                                             12.7s
   ✔ 2ab6f140e216 Pull complete                                             12.8s
   ✔ f8632183bfbd Pull complete                                             12.8s
   ✔ 4c25b193a2b6 Pull complete                                             12.8s
[+] Running 2/2
 ✔ Container devops-kube-news-postgre-1   Started                            0.5s
 ✔ Container devops-kube-news-kubenews-1  Started                            1.2s

Para verificar as configurações aplicadas pode-se utilizar o docker compose config:

~/devops-kube-news$ POSTGRES_TAG=12.17 \
                    POSTGRES_PASSWORD=kubenews \
                    POSTGRES_USER=kubenews \
                    POSTGRES_DB=kubenews \
                    KUBENEWS_TAG=v2 \
                    docker compose config
name: devops-kube-news
services:
  kubenews:
    build:
      context: /home/marcelo/devops-kube-news/src
      dockerfile: Dockerfile
    depends_on:
      postgre:
        condition: service_started
        required: true
    environment:
      DB_DATABASE: kubenews
      DB_HOST: postgre
      DB_PASSWORD: kubenews
      DB_USERNAME: kubenews
    image: marcelodpbarbieri/kube-news:v2
    networks:
      kubenews-net: null
    ports:
      - mode: ingress
        target: 8080
        published: "8080"
        protocol: tcp
  postgre:
    environment:
      POSTGRES_DB: kubenews
      POSTGRES_PASSWORD: kubenews
      POSTGRES_USER: kubenews
    image: postgres:12.17
    networks:
      kubenews-net: null
    ports:
      - mode: ingress
        target: 5432
        published: "5432"
        protocol: tcp
    volumes:
      - type: volume
        source: postgre-docker-vol
        target: /var/lib/postgresql/data
        volume: {}
networks:
  kubenews-net:
    name: devops-kube-news_kubenews-net
    driver: bridge
volumes:
  postgre-docker-vol:
    name: devops-kube-news_postgre-docker-vol

Arquivo de Ambiente

Utilizar um arquivo .env:

~/devops-kube-news$ touch .env
~/devops-kube-news$ vim .env
~/devops-kube-news$ cat .env
POSTGRES_TAG=12.17
POSTGRES_PASSWORD=kubenews
POSTGRES_USER=kubenews
POSTGRES_DB=kubenews
KUBENEWS_TAG=v2

~/devops-kube-news$ docker compose config
name: devops-kube-news
services:
  kubenews:
    build:
      context: /home/marcelo/devops-kube-news/src
      dockerfile: Dockerfile
    depends_on:
      postgre:
        condition: service_started
        required: true
    environment:
      DB_DATABASE: kubenews
      DB_HOST: postgre
      DB_PASSWORD: kubenews
      DB_USERNAME: kubenews
    image: marcelodpbarbieri/kube-news:v2
    networks:
      kubenews-net: null
    ports:
      - mode: ingress
        target: 8080
        published: "8080"
        protocol: tcp
  postgre:
    environment:
      POSTGRES_DB: kubenews
      POSTGRES_PASSWORD: kubenews
      POSTGRES_USER: kubenews
    image: postgres:12.17
    networks:
      kubenews-net: null
    ports:
      - mode: ingress
        target: 5432
        published: "5432"
        protocol: tcp
    volumes:
      - type: volume
        source: postgre-docker-vol
        target: /var/lib/postgresql/data
        volume: {}
networks:
  kubenews-net:
    name: devops-kube-news_kubenews-net
    driver: bridge
volumes:
  postgre-docker-vol:
    name: devops-kube-news_postgre-docker-vol

~/devops-kube-news$ docker compose up -d
[+] Running 2/2
 ✔ Container devops-kube-news-postgre-1   Started                            0.3s
 ✔ Container devops-kube-news-kubenews-1  Started                            0.8s

Por padrão o arquivo .env é considerado, porém também pode ser especificado caso queira utilizar arquivos de ambiente diferentes (i.e., dev.env, hom.env, prd.env etc.)

~/devops-kube-news$ docker compose --env-file .env up -d
[+] Running 2/2
 ✔ Container devops-kube-news-postgre-1   Started                            0.3s
 ✔ Container devops-kube-news-kubenews-1  Started                            0.8s

Valores Padrão

Caso não sejam definidos valores para as variáveis de ambiente podem ser considerados valores padrão utilizando :- ficando ${KUBENEW_TAG:-latest}.

Retirar a declaração da variável de ambiente do arquivo .env:

~/devops-kube-news$ cat .env
POSTGRES_TAG=12.17
POSTGRES_PASSWORD=kubenews
POSTGRES_USER=kubenews
POSTGRES_DB=kubenews

Editar o arquivo compose.yaml:

~/devops-kube-news$ vim compose.yaml

services:
  postgre:
    image: postgres:${POSTGRES_TAG}
    ports:
      - 5432:5432
    environment:
      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD}
      POSTGRES_USER: ${POSTGRES_USER}
      POSTGRES_DB: ${POSTGRES_DB}
    volumes:
      - postgre-docker-vol:/var/lib/postgresql/data
    networks:
      - kubenews-net
  kubenews:
    image: marcelodpbarbieri/kube-news:${KUBENEWS_TAG:-latest}
    build:
      context: ./src
      dockerfile: Dockerfile
    ports:
      - 8080:8080
    depends_on:
      - postgre
    environment:
      DB_DATABASE: ${POSTGRES_DB}
      DB_USERNAME: ${POSTGRES_USER}
      DB_PASSWORD: ${POSTGRES_PASSWORD}
      DB_HOST: postgre
    networks:
      - kubenews-net

volumes:
  postgre-docker-vol:

networks:
  kubenews-net:
    driver: bridge

Destaque para:

  kubenews:
    image: marcelodpbarbieri/kube-news:${KUBENEWS_TAG:-latest}

Verificação da configuração:

~/devops-kube-news$ docker compose config
name: devops-kube-news
services:
  kubenews:
    build:
      context: /home/marcelo/devops-kube-news/src
      dockerfile: Dockerfile
    depends_on:
      postgre:
        condition: service_started
        required: true
    environment:
      DB_DATABASE: kubenews
      DB_HOST: postgre
      DB_PASSWORD: kubenews
      DB_USERNAME: kubenews
    image: marcelodpbarbieri/kube-news:latest
    networks:
      kubenews-net: null
    ports:
      - mode: ingress
        target: 8080
        published: "8080"
        protocol: tcp
  postgre:
    environment:
      POSTGRES_DB: kubenews
      POSTGRES_PASSWORD: kubenews
      POSTGRES_USER: kubenews
    image: postgres:12.17
    networks:
      kubenews-net: null
    ports:
      - mode: ingress
        target: 5432
        published: "5432"
        protocol: tcp
    volumes:
      - type: volume
        source: postgre-docker-vol
        target: /var/lib/postgresql/data
        volume: {}
networks:
  kubenews-net:
    name: devops-kube-news_kubenews-net
    driver: bridge
volumes:
  postgre-docker-vol:
    name: devops-kube-news_postgre-docker-vol

Destaque para:

image: marcelodpbarbieri/kube-news:latest

Construção de Imagem

Se a tag v6 não existir ele cria a imagem:

~/devops-kube-news$ KUBENEWS_TAG=v6 docker compose --env-file .env build
[+] Building 1.1s (11/11) FINISHED                                 docker:default
 => [kubenews internal] load build definition from Dockerfile                0.0s
 => => transferring dockerfile: 163B                                         0.0s
 => [kubenews internal] load metadata for docker.io/library/node:20.10.0-al  1.0s
 => [kubenews internal] load .dockerignore                                   0.0s
 => => transferring context: 2B                                              0.0s
 => [kubenews 1/5] FROM docker.io/library/node:20.10.0-alpine3.18@sha256:32  0.0s
 => [kubenews internal] load build context                                   0.0s
 => => transferring context: 830B                                            0.0s
 => CACHED [kubenews 2/5] WORKDIR /app                                       0.0s
 => CACHED [kubenews 3/5] COPY package*.json .                               0.0s
 => CACHED [kubenews 4/5] RUN npm install                                    0.0s
 => CACHED [kubenews 5/5] COPY . .                                           0.0s
 => [kubenews] exporting to image                                            0.0s
 => => exporting layers                                                      0.0s
 => => writing image sha256:157ac0c3edb100e995c900a98bd8dd4021b907964ec992d  0.0s
 => => naming to docker.io/marcelodpbarbieri/kube-news:v6                    0.0s
 => [kubenews] resolving provenance for metadata file                        0.0s
marcelo@Latitude5440:~/devops-kube-news$ docker image ls
REPOSITORY                    TAG       IMAGE ID       CREATED        SIZE
marcelodpbarbieri/kube-news   v6        157ac0c3edb1   25 hours ago   169MB
...