Detailed explanation of docker compose configuration

2.1 image

• web user defined service name
• Image can be specified as the image name or image ID. if it does not exist locally, it will automatically try to pull

services: web: image: redis

2.2 build

• The service startup can be based on 2.1 image or Dockerfile. The build task will be executed when the service is started up.
• The sub tag context sets the context root directory
• The sub tag Dockerfile specifies the Dockerfile file
• The child tag args specifies the environment variables used during the build

  services: web: build: context: ../ dockerfile: Dockerfile args: - buildno=1 - password=123456

• Specifying both the image and build tags will name the built image after the image

  services: web: build: . image: webapp:tag

2.3 command

• Using command overrides the command to be executed by default after the image is started

  services: web: command: redis-server /etc/redis/redis.conf --appendonly yes

  services: web: command: ["redis-server", "/etc/redis/redis.conf", "--appendonly", "yes"]

2.4 container_name

• The format of docker compose startup container name is: < project name > < service name > < serial number >
• You can also use container_name custom container name

  services: web: container_name: redis-6379

2.5 depends_on

• Generally, in a project, the container needs to have a specific start sequence, otherwise it will fail to start due to dependency problems.
• Example: if you start the application container without starting the database, the application container will exit because the database cannot be found
• Solution: dependencies_ on

  services: web: build: . depends_on: - db - redis redis: image: redis:latest db: image: mysql:5.7

2.6 dns

• The same purpose as the -- dns parameter in docker run

  services: web: dns: 8.8.8.8

  services: web: dns: - 8.8.8.8 - 114.114.114.114

2.7 entrypoint

• There is an instruction entrypoint in Dockerfile to specify the access point. The definition of entrypoint in docker-compose.yml will overwrite the definition in Dockerfile

  services: web: entrypoint: java -jar app.jar --spring.profiles.active=release

  services: web: entrypoint: - java - -jar - app.jar - --spring.profiles.active=release

2.8 environment

• It is equivalent to the function of docker run -e

  services: mysql: image: mysql environment: - MYSQL_ROOT_PASSWORD=123456 - MYSQL_ALLOW_EMPTY_PASSWORD=yes

2.9 extra_hosts

• Adding the host name mapping is equivalent to adding records to / etc/hosts, and is equivalent to the function of docker run -- add host

  services: web: extra_hosts: - webnode1:192.168.171.100 - webnode2:192.168.171.101

• This is what / etc/hosts in the container can see

  192.168.171.100 webnode1 192.168.171.101 webnode2

2.10 ports

• The port mapping label is equivalent to the docker run -p function

  services: web: ports: - 80:80 - 1180:1180

2.11 volumes

• Mounting a directory or an existing data volume container is equivalent to the docker run -v function
• HOST:CONTAINER HOST:CONTAINER:ro,: ro means read-only, and the default is read-write

  services: web: volumes: - /usr/share/zoneinfo/Asia/Shanghai:/etc/localtime:ro - ./webdist:/home/webdist

2.12 networks

• Join the specified network

  services: web: networks: - web-net - backend-net

2.13 cap_add,cap_drop

• Add or remove the kernel functionality of the container

2.14 cgroup_parent

• Specifies the parent cgroup of the container

2.15 others

• There are other single value Tags: user working_dir hostname privileged restart

  services: web: user: mysql working_dir: /home/webdist hostname: webnode privileged: true restart: always

https://www.jianshu.com/p/2217cfed29d7

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