入门-service-第二层

前提

• dockers version:1.13或者更高(17.03.1-ce)
• 安装Docker Compose

理解service

在一个分布式应用中，不同的部分都被称为service。

services实际上是containers in production。一个service启动一个image，它规定了image的运行方式(使用哪些端口，需要多少个container的复制集才能满足service等)。

docker-compose.yml文件可以很简单的定义、运行、规划services。

docker-compose.yml

可以把该文件保存在任何位置。确保image已经上传。

version: "3"
services:
  web:
    # replace username/repo:tag with your name and image details
    image: username/repository:tag
    deploy:
      replicas: 5
      resources:
        limits:
          cpus: "0.1"
          memory: 50M
      restart_policy:
        condition: on-failure
    ports:
      - "80:80"
    networks:
      - webnet
networks:
  webnet:

• 从registry拉取image
• 运行5个image的实例作为服务，称为web，限制每个使用最多10%的CPU和50M的内存
• 如果停止运行立即重新启动container
• 映射本地80端口到web的80端口
• 指导web的containers通过负载均衡网络webnet共享80端口。(在内部，containers will publish to web’s port 80 at an ephemeral port)
• 使用默认设置定义webnet网络

运行新的负债均衡的app

docker swarm init

# app name: getstartedlab
docker stack deploy -c docker-compose.yml getstartedlab

# See a list of the five containers you just launched
docker stack ps getstartedlab

Scale(规划) the app

可以修改replicas，保存，重新运行docker stack deploy:

docker stack deploy -c docker-compose.yml getstartedlab

Docker will do an in-place update, no need to tear the stack down first or kill any containers.

摧毁app和swarm

docker stack rm getstartedlab

This removes the app, but our one-node swarm is still up and running (as shown by docker node ls). Take down the swarm with docker swarm leave --force.

docker stack ls              # List all running applications on this Docker host
docker stack deploy -c <composefile> <appname>  # Run the specified Compose file
docker stack services <appname>       # List the services associated with an app
docker stack ps <appname>   # List the running containers associated with an app
docker stack rm <appname>                             # Tear down an application