掌握Dockerfile、Docker Compose与Docker Swarm使用

331 02-17

一、Dockerfile的构建

1、指定镜像

采用FROM指令：

FROM 指定镜像名称

2、设置标签信息

对镜像进行备注说明：

LABEL manager="admin" \
label1="docker build1" \
lable2="docker build2"

3、运行命令

容器运行后，执行的指令

RUN echo "docker build run."

4、容器启动指令

CMD sleep 6;echo start success

5、Dockerfile 的编写示例

# Dockerfile使用的镜像
FROM alpine

#镜像标签配置
LABEL manager="admin" \
label1="docker build1" \
lable2="docker build2"

#运行的指令
RUN echo "docker build run."

#容器启动后的执行命令
CMD sleep 6;echo start success

Dockerfile 主要分为四部分：镜像信息、维护信息、操作指令、启动时执行指令。

CMD与ENTRYPOINT的差异:

1. CMD指令指定的容器启动时命令可以被docker run指定的命令覆盖，而ENTRYPOINT指令指定的命令不能被覆盖，而是将docker run指定的参数当做ENTRYPOINT指定命令的参数；
例：
CMD ["ls","-a"]
docker run xxx -l 会替换为 -l 执行， 会报错。
2. CMD指令可以为ENTRYPOINT指令设置默认参数，而且可以被docker run指定的参数覆盖；
例：
ENTRYPOINT ["ls","-a"]
docker run xxx -l 会拼接为 ls -al执行。

如果运行JAVA程序, 增加ENTRYPOINT：

ENTRYPOINT [ "sh", "-c", "java -Djava.security.egd=file:/dev/./urandom
$JAVA_OPTS -jar /app.jar $PARAMS" ]
# 运行命令 docker run -e JAVA_OPTS="-Xmx512m -Xms33 -" -e PARAMS="--
spring.profiles=dev --server.port=8080" -jar /app/app.jar

6、运行容器

docker run --name test1  -it dockerfile:test1

7、镜像的存储

查看镜像信息：

docker image inspect my-wizard:0.1

存储目录结构：

 "GraphDriver": {
            "Data": {
                "LowerDir": "/var/lib/docker/overlay2/b7e19d896235074801e65678900f1eb9e3d42a15961e1c5776e821a48c508602/diff:/var/lib/docker/overlay2/94c244b15f5d5290dc48ea41fe90e30292169c1ad1316b4b4508a26043a03889/diff:/var/lib/docker/overlay2/51e4f5054f8035f78df429174458d3511c75086bacd9bc22727ba3b4bdf1ee17/diff:/var/lib/docker/overlay2/fe000be05464f9548d95b24c0773ec5fbefd9f18bc6b393d2fe2731e9bd5b929/diff:/var/lib/docker/overlay2/d257f693e8aa47470bb2a0ea82fcc833d5560e3b471cb008b8d00ff29979e90c/diff:/var/lib/docker/overlay2/3648999483d13c18d34f00d90d843b3aca2abfdc946180730593fecb8585c673/diff:/var/lib/docker/overlay2/3f469b0f602b3f8bf2d85a867652cb045c86bb44da93599a440c6af66c8c4702/diff:/var/lib/docker/overlay2/74114f4a8911f8bee5a793d16b9e66417033aaa3b2763920fd4e7203f2a83aeb/diff:/var/lib/docker/overlay2/7fe7e08fc852d57d1cdf3d8ffce3969da42af3f7c82f01b06501364f86cd615c/diff:/var/lib/docker/overlay2/b59d29226dd54f956383976ee17c2098e351fe73ec27794e35740a4af0467a19/diff:/var/lib/docker/overlay2/83054ea9dfefb4e0f666a640f82476be7b6ee2f0e050b9afc486a7eef755a0f1/diff:/var/lib/docker/overlay2/298e882043803bbafefbbcdd98cdc78df14f4bfa789867be918c60291d1b2ba4/diff:/var/lib/docker/overlay2/2eed01572ca6f1212afceff327c71b4d6bb92033b17ce7ec1476d72afed7b194/diff:/var/lib/docker/overlay2/3284164b93f7945defcbb61bb7eb0d78989b69acd0f20acb2a04b3ac9f6478f1/diff:/var/lib/docker/overlay2/2927eeb30fe0e11cb65dd08a196b9f63e9fd5f6e689aa2e71c58be47d043bef9/diff:/var/lib/docker/overlay2/92a64758e128809c3d6a5ce4bda56f231d969c9915cdc6891031dfaa13c5bf40/diff:/var/lib/docker/overlay2/ad0138bb13e3a6549a967a03be1338680fa79d65f77df0a24e3e3905fa31bb49/diff:/var/lib/docker/overlay2/3dd833c5349e77df38958ab59080311227c84dffd9e85d476d137ad5404a8417/diff:/var/lib/docker/overlay2/19b0730a578cbdf1bde44a7c0296c6dcff39d46154435370231e0b090f2989f8/diff:/var/lib/docker/overlay2/a4b2e0843b03de43dec536f958cb46072c8b5f33bc4cc2429eb92e098d6c3869/diff:/var/lib/docker/overlay2/e659df56cceb80589bfd6d68df3ef703773450158f4f682f5c2b3ac05308264d/diff:/var/lib/docker/overlay2/2e950590bd3aff9d24c436e45a8f53afbc6a5dec7c3cf86223473fa6953dffda/diff:/var/lib/docker/overlay2/f82ab6a6e0611a78a95611d281245b2c2edfaa273d29d88de989b081f79651bb/diff:/var/lib/docker/overlay2/c0c628c8cdf5641f1642eff0f42a5f12ab178cb596e6bce7a86efe725a7da333/diff:/var/lib/docker/overlay2/1041b58a07cfbf956c4a2a2ff2adc93ef1e3f85813dab0bac069452837c5f9fa/diff:/var/lib/docker/overlay2/0247958590c10ef1c20789c2131413b668357348af09955ac8f118b8723d7f5f/diff:/var/lib/docker/overlay2/a8896150c3e359092e2e6d62b755c440e13ee4f8db990135800e0ef46d7894c1/diff",
                "MergedDir": "/var/lib/docker/overlay2/66e9b11cf699cbdc26eac8dfd363274ac0cf601804ae79999c31265899204d4a/merged",
                "UpperDir": "/var/lib/docker/overlay2/66e9b11cf699cbdc26eac8dfd363274ac0cf601804ae79999c31265899204d4a/diff",
                "WorkDir": "/var/lib/docker/overlay2/66e9b11cf699cbdc26eac8dfd363274ac0cf601804ae79999c31265899204d4a/work"
            },
            "Name": "overlay2"
        },

二、Docker Compose的使用

1、安装Docker Compose

进入
https://github.com/docker/compose/releases检索docker引擎所对应的版本：

2、执行安装：

curl -SL https://github.com/docker/compose/releases/download/1.29.0/docker-compose-linux-x86_64 -o /usr/local/bin/docker-compose
sudo chmod +x /usr/local/bin/docker-compose

3、创建一个python应用脚本

app.py

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)

创建依赖信息文件：

requirements.txt

flask
redis

4、创建Dockerfile文件

# syntax=docker/dockerfile:1
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
EXPOSE 5000
COPY . .
CMD ["flask", "run"]

5、执行构建

创建名称为web的镜像

docker build -t web .

6、创建docker-compose配置文件

version: "3.9" #指定版本号;查看文档https://docs.docker.com/compose/compose-file/
services: #所有需要启动的服务
  web: #第一个服务的名字
    build: # 可手动执行创建镜像: docker build -t xxx -f Dockerfile .
      dockerfile: Dockerfile
      context: .
    image: 'hello:py'
    ports: #指定启动容器暴露的端口
      - "5000:5000"
  redis: #第二个服务的名字
    image: "redis:alpine"

7、启动执行：

通过命令启动： docker-compose up

加上-d参数，以后台方式启动。

[root@localhost composetest]# docker-compose up
Starting composetest_web_1   ... done
Starting composetest_redis_1 ... done
Attaching to composetest_redis_1, composetest_web_1
redis_1  | 1:C 04 Nov 2022 17:19:23.281 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
redis_1  | 1:C 04 Nov 2022 17:19:23.281 # Redis version=7.0.5, bits=64, commit=00000000, modified=0, pid=1, just started
redis_1  | 1:C 04 Nov 2022 17:19:23.281 # Warning: no config file specified, using the default config. In order to specify a config file use redis-server /path/to/redis.conf
redis_1  | 1:M 04 Nov 2022 17:19:23.281 * monotonic clock: POSIX clock_gettime
redis_1  | 1:M 04 Nov 2022 17:19:23.282 * Running mode=standalone, port=6379.
redis_1  | 1:M 04 Nov 2022 17:19:23.282 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
redis_1  | 1:M 04 Nov 2022 17:19:23.282 # Server initialized
redis_1  | 1:M 04 Nov 2022 17:19:23.282 # WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.
redis_1  | 1:M 04 Nov 2022 17:19:23.282 * Loading RDB produced by version 7.0.5
redis_1  | 1:M 04 Nov 2022 17:19:23.282 * RDB age 605 seconds
redis_1  | 1:M 04 Nov 2022 17:19:23.282 * RDB memory usage when created 0.82 Mb
redis_1  | 1:M 04 Nov 2022 17:19:23.282 * Done loading RDB, keys loaded: 1, keys expired: 0.
redis_1  | 1:M 04 Nov 2022 17:19:23.282 * DB loaded from disk: 0.000 seconds
redis_1  | 1:M 04 Nov 2022 17:19:23.282 * Ready to accept connections
web_1    |  * Serving Flask app 'app.py'
web_1    |  * Debug mode: off
web_1    | WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead.
web_1    |  * Running on all addresses (0.0.0.0)
web_1    |  * Running on http://127.0.0.1:5000
web_1    |  * Running on http://172.18.0.3:5000
web_1    | Press CTRL+C to quit

8、验证访问：

[root@localhost bin]# curl http://127.0.0.1:5000
Hello World! I have been seen 4 times.
[root@localhost bin]# curl http://172.18.0.3:5000
Hello World! I have been seen 5 times.

9、停止服务

[root@localhost composetest]# docker-compose stop redis
Stopping composetest_redis_1 ... done
[root@localhost composetest]# docker-compose stop web
Stopping composetest_web_1 ... done

这里的服务名字与docker-compose配置文件中的名称对应。

三、Docker Swarm集群模式

1、创建Dockerfile

创建一个需要采用集群模式部署的Dockerfile:

version: "3.7"
  services:
    app:  #定义应用程序的容器
      image: node:12-alpine
      command: sh -c "yarn install && yarn run dev"
      ports:
        - 3000:3000
      working_dir: /app
      volumes:
        - ./:/app
      environment:
        MYSQL_HOST: mysql
        MYSQL_USER: root
        MYSQL_PASSWORD: secret
        MYSQL_DB: todos
      networks:  # 加入application和databases两个网络
        - application
        - databases
      deploy: #安装docker swarm
        replicas: 6 #指定副本：部署到加入swarm集群的不同的节点（负载均衡+高可用）
    mysql: # 定义mysql数据库的容器
      image: mysql:5.7
      volumes:
        - mysql-data:/var/lib/mysql
      environment:
        MYSQL_ROOT_PASSWORD: secret
        MYSQL_DATABASE: todos
      networks: #这个服务加入hello自定义网络
        - databases
      deploy: #安装docker swarm
        replicas: 6 #指定副本：处于不同的服务器（负载均衡+高可用）
        
    redis: # 定义redis缓存的容器
      image: redis
      networks:
        - application 
        
  # 定义全局的配置信息，包括volumes与networks
  volumes:
    mysql-data:
  networks:
    application:
    databases:

2、集群初始化

主节点进行初始化：

[root@localhost ~]# docker swarm init
Swarm initialized: current node (oyje6kmyqnot8fop89msrs1wf) is now a manager.

To add a worker to this swarm, run the following command:

    docker swarm join --token SWMTKN-1-1iq2u7f21fty2wyih2xh6j8jzb87uiwi2gpqclg77ykii642kz-bupmi5rixs4a7zaho7i8o8kjf 10.10.20.15:2377

To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.

[root@localhost ~]#

其他节点加入执行：

docker swarm join --token SWMTKN-1-1iq2u7f21fty2wyih2xh6j8jzb87uiwi2gpqclg77ykii642kz-bupmi5rixs4a7zaho7i8o8kjf 10.10.20.15:2377

3、多个主节点的加入配置（高可用）

在集群主节点执行：

[root@localhost ~]# docker swarm join-token manager
To add a manager to this swarm, run the following command:

    docker swarm join --token SWMTKN-1-1iq2u7f21fty2wyih2xh6j8jzb87uiwi2gpqclg77ykii642kz-1dturcr1g93eak84d2jlvfbop 10.10.20.15:2377

在其他集群主节点执行

docker swarm join --token SWMTKN-1-1iq2u7f21fty2wyih2xh6j8jzb87uiwi2gpqclg77ykii642kz-1dturcr1g93eak84d2jlvfbop 10.10.20.15:2377

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