1、单机多容器部署
在之前的章节中我们已经对Docker有了初步的认知，知道如何去部署项目，如何实现多容器的通信。但是大家应该也体会到了部署容器时的繁琐。每部署一个容器都需要很多的命令去操作，容器多了之后我们都不记得这个容器是加了什么参数了，而且也需要花费较多的时间去部署，如果能像写配置文件一样去维护多个容器，那一定很方便。
接下来要说的 Docker Compose 就是用来解放我们的双手的，通过配置 yaml 文件去实现容器的部署，只需要配几个参数就能做到多容器的配置、通信和维护了。
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Docker Compose
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安装
如果是Mac或者Windows系统，在安装了Docker的时候就已经内置了Docker Compose了，如果是Linux系统，则需要手动安装。
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# 第一步 sudo curl -L "https://github.com/docker/compose/releases/download/1.25.4/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose # 第二步 sudo chmod +x /usr/local/bin/docker-compose
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示例
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创建目录
$ mkdir composetest $ cd composetest -
创建 app.py 文件
import time import redis from flask import Flask app = Flask(__name__) cache = redis.Redis(host='redis', port=6379) def get_hit_count(): retries = 5 while True: try: return cache.incr('hits') except redis.exceptions.ConnectionError as exc: if retries == 0: raise exc retries -= 1 time.sleep(0.5) @app.route('/') def hello(): count = get_hit_count() return 'Hello World! I have been seen {} times.\n'.format(count) -
创建 requirements.txt 文件
flask redis -
编写Dockerfile
FROM python:3.7-alpine WORKDIR /code ENV FLASK_APP app.py ENV FLASK_RUN_HOST 0.0.0.0 RUN apk add --no-cache gcc musl-dev linux-headers COPY requirements.txt requirements.txt RUN pip install -r requirements.txt COPY . . CMD ["flask", "run"] -
编写docker-compose.yml
version: '3' # docker-compose的版本 services: web: # 构建一个容器,名为 web build: . # 使用本地Dockerfile构建 ports: # 端口映射 - "5000:5000" redis: # 构建一个容器,名为 redis image: "redis:alpine" # 从远端仓库拉取 -
运行docker-compose
- 默认会寻找当前目录下的 docker-compose.yml
- 如果要指定名称则加
-f xxx.yml参数
[root@10 composetest]# docker-compose up -d -
测试功能
每访问一次页面，都会调用 Redis 的 increment 递增访问次数。
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docker-compose.yml文件 参数介绍
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version: '3'
- 表示docker-compose的版本
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services
- 一个service表示一个container
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networks
- 相当于docker network create app-net
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volumes
- 相当于
-v v1:/var/lib/mysql
- 相当于
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image
- 表示使用哪个镜像，要从远端拉取
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build
- 表示使用本地Dockerfile构建镜像
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ports
- 相当于 -p 8080:8080
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environment
- 相当于 -e
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docker-compose常见操作
- 查看版本
- docker-compose version
- 根据 yml 创建service
- docker-compose up
- 指定 yaml：docker-compose up -f xxx.yaml
- 后台运行：docker-compose up -d
- 查看启动成功的service
- docker-compose ps
- 也可以使用 docker ps
- 查看images
- docker-compose images
- 停止/启动service
- docker-compose stop/start
- 删除service[同时会删除掉network和volume]
- docker-compose down
- 进入到某个service
- docker-compose exec redis sh
- 查看版本
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scale扩缩容
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准备 docker-compose.yml 文件，注意去除 ports 参数，防止端口冲突
version: '3' services: web: build: . networks: - app-net redis: image: "redis:alpine" networks: - app-net networks: app-net: driver: bridge -
创建 service 容器
- docker-compose up -d
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对 web 容器进行扩缩容
- docker-compose up --scale web=5 -d
- 表示增加 web 容器数量到 5
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查看容器
- docker-compose ps
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2、多机多容器部署
Docker Compose只是能在单机下对容器进行管理，如果涉及到多台宿主机它就没办法了，这时就需要另一个技术Docker Swarm。
Docker Swarm可以实现多机下的容器管理、通信与编排，不过这里也是不会讲太多，因为现在的容器编排主流是 Kubernetes！
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Docker Swarm
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安装
任意平台下安装过Docker就已经内置了Docker Swarm了，所以无需安装
但是我们需要准备多台机器去测试多机部署，这里我们用虚拟机代替
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使用vagrantfile来安装多台虚拟机
boxes = [ { :name => "manager-node", :eth1 => "192.168.50.111", :mem => "1024", :cpu => "1" }, { :name => "worker01-node", :eth1 => "192.168.50.112", :mem => "1024", :cpu => "1" }, { :name => "worker02-node", :eth1 => "192.168.50.113", :mem => "1024", :cpu => "1" } ] Vagrant.configure(2) do |config| config.vm.box = "centos/7" boxes.each do |opts| config.vm.define opts[:name] do |config| config.vm.hostname = opts[:name] config.vm.provider "vmware_fusion" do |v| v.vmx["memsize"] = opts[:mem] v.vmx["numvcpus"] = opts[:cpu] end config.vm.provider "virtualbox" do |v| v.customize ["modifyvm", :id, "--memory", opts[:mem]] v.customize ["modifyvm", :id, "--cpus", opts[:cpu]] v.customize ["modifyvm", :id, "--name", opts[:name]] end config.vm.network :public_network, ip: opts[:eth1] end end end -
一次构建多节点的情况下，通过vagrant ssh [node name]进入虚拟机
vagrant ssh [manager-node / worker01-node / worker02-node]初始化步骤、配置xshell连接与第一章节一致，这里不细讲了
在每台虚拟机中安装Docker
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搭建Swarm集群
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在 manager 节点中初始化集群配置
[root@10 ~]# docker swarm init --advertise-addr=192.168.50.111 Swarm initialized: current node (rf5m8pyx7w7i2tutxumspn3ph) is now a manager. To add a worker to this swarm, run the following command: # 这段命令是需要到worker节点执行,表示加入集群 docker swarm join --token SWMTKN-1-3wwhsp6boxd5damm9f549v21eshj5cdkuu97xmz6vo1pkvuhrr-6wtpwh1ewl3ib3ryr9j5dayzc 192.168.50.111:2377 To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions. -
worker 节点加入集群
[root@10 ~]# docker swarm join --token SWMTKN-1-3wwhsp6boxd5damm9f549v21eshj5cdkuu97xmz6vo1pkvuhrr-6wtpwh1ewl3ib3ryr9j5dayzc 192.168.50.111:2377 This node joined a swarm as a worker. -
在manager节点查看集群状态
hostname 需要手动修改，默认是展示网卡ip的，比如：hostnamectl set-hostname manager-node
[root@manager-node ~]# docker node ls ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION rf5m8pyx7w7i2tutxumspn3ph * manager-node Ready Active Leader 19.03.7 ncgr8mqhhz47itjqcyhamtn62 worker01-node Ready Active 19.03.7 -
成员节点类型转换
可以将worker提升成manager，从而保证manager的高可用，但这个提升只是让worker有成为manager的资格，没有提升的worker节点无权成为manager
[root@manager-node ~]# docker node promote ncgr8mqhhz47itjqcyhamtn62 Node ncgr8mqhhz47itjqcyhamtn62 promoted to a manager in the swarm. # 现在worker节点的 manager status变成 Reachable,表示拥有变成Leader的权限了 [root@manager-node ~]# docker node ls ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION ncgr8mqhhz47itjqcyhamtn62 10.0.2.15 Ready Active Reachable 19.03.7 rf5m8pyx7w7i2tutxumspn3ph * 10.0.2.15 Ready Active Leader 19.03.7 #降级可以用demote [root@manager-node ~]# docker node demote ncgr8mqhhz47itjqcyhamtn62 Manager ncgr8mqhhz47itjqcyhamtn62 demoted in the swarm. [root@manager-node ~]# docker node ls ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION rf5m8pyx7w7i2tutxumspn3ph * manager-node Ready Active Leader 19.03.7 ncgr8mqhhz47itjqcyhamtn62 worker01-node Ready Active 19.03.7
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Docker Swarm常用操作
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创建一个tomcat的service
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docker service create --name my-tomcat tomcat
[root@manager-node ~]# docker service create --name my-tomcat tomcat h9xki026ivexy28r3242izu5g overall progress: 1 out of 1 tasks 1/1: running [==================================================>] # 创建完成后会使用5秒时间对容器的可用性进行验证 verify: Waiting 5 seconds to verify that tasks are stable... # 5秒结束会变成 Service converged verify: Service converged
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删除容器
- docker service rm my-tomcat
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查看当前Swarm的service
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docker service ls
[root@manager-node ~]# docker service ls ID NAME MODE REPLICAS IMAGE PORTS zdf8vgmay2hx my-tomcat replicated 1/1 tomcat:latest
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查看service的启动日志
- docker service logs my-tomcat
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查看service的详情
- docker service inspect my-tomcat
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查看my-tomcat运行在哪个node上
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docker service ps my-tomcat
# 可以看到容器是创建在manager节点的 [root@manager-node ~]# docker service ps my-tomcat ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS s83wnalw3xx0 my-tomcat.1 tomcat:latest manager-node Running Running 3 minutes ago
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水平扩容service
[root@manager-node ~]# docker service scale my-tomcat=3 my-tomcat scaled to 3 overall progress: 3 out of 3 tasks 1/3: running [==================================================>] 2/3: running [==================================================>] 3/3: running [==================================================>] verify: Service converged # 可以发现，my-tomcat的service会分别部署到不同宿主机中 [root@manager-node ~]# docker service ps my-tomcat ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS s83wnalw3xx0 my-tomcat.1 tomcat:latest manager-node Running Running 7 minutes ago qs8qfoo7ge0n my-tomcat.2 tomcat:latest worker01-node Running Running 28 seconds ago 4m661e5msju9 my-tomcat.3 tomcat:latest worker01-node Running Running 28 seconds ago如果不用docker service ps，执行docker ps，会发现container的name和service名称不一样，这是正常的，也要注意别搞混了
[root@worker01-node ~]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 59ea2502ede4 tomcat:latest "catalina.sh run" 10 minutes ago Up 10 minutes 8080/tcp my-tomcat.1.u6o4mz4tj3969a1p3mquagxok -
如果某个node上的my-tomcat挂掉了，这时候会自动扩展
[root@worker01-node ~]# docker rm -f 0e9b5d804c25 # 现在manager上运行2个容器了 [root@manager-node ~]# docker service ps my-tomcat ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS s83wnalw3xx0 my-tomcat.1 tomcat:latest manager-node Running Running 10 minutes ago 1qbunkr1fs5j my-tomcat.2 tomcat:latest manager-node Running Running 6 seconds ago qs8qfoo7ge0n \_ my-tomcat.2 tomcat:latest worker01-node Shutdown Failed 12 seconds ago "task: non-zero exit (137)" 4m661e5msju9 my-tomcat.3 tomcat:latest worker01-node Running Running 3 minutes ago
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多机通信 overlay 网络
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使用swarm创建容器后，会自动生成一个overlay的网络模式
[root@manager-node ~]# docker network ls NETWORK ID NAME DRIVER SCOPE f707fc44e537 bridge bridge local d2f72fb35175 host host local w5p8g8c4z5sk ingress overlay swarm a2f09c4b5e89 none null local
+ 创建一个overlay网络，用于docker swarm中多机通信 ```ruby # -d 表示指定网络模式类型 [root@manager-node ~]# docker network create -d overlay my-overlay-net wekfq4m34mc5welq5d7xvc6d0 # 此时worker node查看不到，只有创建容器且分配到该宿主机之后才可以看到 [root@worker01-node ~]# docker network ls NETWORK ID NAME DRIVER SCOPE c7f42990d130 bridge bridge local 81a19f795c7e host host local w5p8g8c4z5sk ingress overlay swarm 7356babbeab8 none null local [root@manager-node ~]# docker service create --name my-tomcat --network my-overlay-net tomcat gl90f1frfeae9cutnz0uc7i72 overall progress: 1 out of 1 tasks 1/1: running [==================================================>] verify: Service converged # 扩容 [root@10 ~]# docker service scale my-tomcat=3 my-tomcat scaled to 3 overall progress: 3 out of 3 tasks 1/3: running [==================================================>] 2/3: running [==================================================>] 3/3: running [==================================================>] verify: Service converged # 现在worker节点可以看到之前在manager节点创建的overlay网络模式了 [root@worker01-node ~]# docker network ls NETWORK ID NAME DRIVER SCOPE c7f42990d130 bridge bridge local 81a19f795c7e host host local w5p8g8c4z5sk ingress overlay swarm wekfq4m34mc5 my-overlay-net overlay swarm 7356babbeab8 none null localoverlay网络与brige网络模式的区别就是overlay是多机多容器之间通信的，brige是单机多容器通信
通过docker swarm创建的容器，无论访问哪台宿主机的ip地址，最终都可以访问到正确的容器中的项目。如果是使用容器名称进行通信，还会自动做到负载均衡。
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docker stack
docker stack与docker-compose其实是一样的，compose是单机容器管理，stack是多机容器管理。
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新建service.yml文件
version: '3' services: wordpress: image: wordpress ports: - 8080:80 environment: WORDPRESS_DB_HOST: db WORDPRESS_DB_USER: exampleuser WORDPRESS_DB_PASSWORD: examplepass WORDPRESS_DB_NAME: exampledb networks: - ol-net volumes: - wordpress:/var/www/html deploy: mode: replicated replicas: 3 restart_policy: condition: on-failure delay: 5s max_attempts: 3 update_config: parallelism: 1 delay: 10s db: image: mysql:5.7 environment: MYSQL_DATABASE: exampledb MYSQL_USER: exampleuser MYSQL_PASSWORD: examplepass MYSQL_RANDOM_ROOT_PASSWORD: '1' volumes: - db:/var/lib/mysql networks: - ol-net deploy: mode: global placement: constraints: - node.role == manager volumes: wordpress: db: networks: ol-net: driver: overlay -
根据service.yml创建service
# -c 指定配置文件 [root@manager-node swarmtest]# docker stack deploy -c service.yml my-service Creating network my-service_ol-net Creating service my-service_db Creating service my-service_wordpress -
测试
- 浏览器访问 [任意节点的ip]:8080
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> 可以确认，无论访问集群中哪个节点的ip，docker都可以帮助自动指向正确的容器
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docker stack常用操作
- 根据service.yml创建service
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docker stack deploy -c service.yml my-service
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查看stack具体信息
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docker stack ls
[root@manager-node swarmtest]# docker stack ls NAME SERVICES ORCHESTRATOR my-service 2 Swarm
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查看具体的service
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docker stack services my-service
[root@manager-node swarmtest]# docker stack services my-service ID NAME MODE REPLICAS IMAGE PORTS 6h3ipjnx32sc my-service_wordpress replicated 0/3 wordpress:latest *:8080->80/tcp cwo60mztuoou my-service_db global 1/1 mysql:5.7
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查看某个service详情
- docker service inspect my-service_db
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