Docker初体验，创建并导出第一个本地镜像

准备工作，创建一个目录docker-test，用来存放创建镜像所需的文件，同事完成相关文件的创建。

[root@ChatDevOps ~]# mkdir docker-test [root@ChatDevOps ~]# cd docker-test/ [root@ChatDevOps docker-test]# touch Dockerfile [root@ChatDevOps docker-test]# touch app.py [root@ChatDevOps docker-test]# touch requirements.txt

在Dockerfile中加入以下内容：

# Use an official Python runtime as a parent image FROM python:2.7-slim # Set the working directory to /app WORKDIR /app # Copy the current directory contents into the container at /app ADD . /app # Install any needed packages specified in requirements.txt RUN pip install --trusted-host pypi.python.org -r requirements.txt # Make port 80 available to the world outside this container EXPOSE 80 # Define environment variable ENV NAME World # Run app.py when the container launches CMD ["python", "app.py"]

在app.py中增加以下内容：

from flask import Flask from redis import Redis, RedisError import os import socket # Connect to Redis redis = Redis(host="redis", db=0, socket_connect_timeout=2, socket_timeout=2) app = Flask(__name__) @app.route("/") def hello(): try: visits = redis.incr("counter") except RedisError: visits = "<i>cannot connect to Redis, counter disabled</i>" html = "<h3>Hello {name}!</h3>" \ "<b>Hostname:</b> {hostname}<br/>" \ "<b>Visits:</b> {visits}" return html.format(name=os.getenv("NAME", "world"), hostname=socket.gethostname(), visits=visits) if __name__ == "__main__": app.run(host='0.0.0.0', port=80)

在requirements.txt中添加以下内容：

Flask Redis

安装pip，并使用pip安装Flask和Redis：

[root@ChatDevOps docker-test]# curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py [root@ChatDevOps docker-test]# python get-pip.py [root@ChatDevOps docker-test]# pip install -r requirements.txt [root@ChatDevOps docker-test]# rm -rf get-pip.py [root@ChatDevOps docker-test]# ls app.py Dockerfile requirements.txt

执行构建命令，使用-t选项指定镜像的仓库、标签。注意，镜像名称必须小写。

[root@ChatDevOps docker-test]# docker build -t local/chatdevops . Sending build context to Docker daemon 4.608 kB Step 1/7 : FROM python:2.7-slim Trying to pull repository docker.io/library/python ... 2.7-slim: Pulling from docker.io/library/python ... ... [root@ChatDevOps docker-test]# docker image ls REPOSITORY TAG IMAGE ID CREATED SIZE local/chatdevops latest fc26e265213a 21 minutes ago 151 MB docker.io/fedora latest cc510acfcd70 2 weeks ago 253 MB

使用刚刚创建的镜像构建一个容器，并将容器的80端口映射到本机的4000端口。

[root@ChatDevOps docker-test]# docker run -p 4000:80 local/chatdevops * Serving Flask app "app" (lazy loading) * Environment: production WARNING: Do not use the development server in a production environment. Use a production WSGI server instead. * Debug mode: off * Running on http://0.0.0.0:80/ (Press CTRL+C to quit) 172.17.0.1 - - [23/May/2018 04:21:04] "GET / HTTP/1.1" 200 - 172.17.0.1 - - [23/May/2018 04:21:04] "GET /favicon.ico HTTP/1.1" 404 - 172.17.0.1 - - [23/May/2018 04:22:24] "GET / HTTP/1.1" 200 -

在浏览器看一下效果：

镜像制作完成，导出镜像，选项-o表示将导出内容写入一个文件，替代了标准输出。

[root@ChatDevOps docker-test]# docker save -o chatdevops.tar local/chatdevops [root@ChatDevOps docker-test]# ll 总用量 153716 -rw-r--r--. 1 root root 666 5月 23 09:52 app.py -rw-------. 1 root root 157392896 5月 23 11:47 chatdevops.tar -rw-r--r--. 1 root root 509 5月 23 11:12 Dockerfile -rw-r--r--. 1 root root 12 5月 23 09:51 requirements.txt

在异机上导入刚刚创建的镜像。

[root@ChatDevOps docker-test]# scp chatdevops.tar root@10.1.1.1.12:/root/ [root@ChatDevOps ~]# ll 总用量 153704 -rw-------. 1 root root 157392896 5月 23 14:30 chatdevops.tar [root@ChatDevOps ~]# docker load --input chatdevops.tar ba291263b085: Loading layer [==================================================>] 82.94 MB/82.94 MB 10dd6271862c: Loading layer [==================================================>] 7.487 MB/7.487 MB 4e1a46391216: Loading layer [==================================================>] 46.96 MB/46.96 MB a40d037570f2: Loading layer [==================================================>] 7.649 MB/7.649 MB d9bad830e350: Loading layer [==================================================>] 1.536 kB/1.536 kB 16b29278858d: Loading layer [==================================================>] 5.12 kB/5.12 kB b6e1c4419841: Loading layer [==================================================>] 12.32 MB/12.32 MB Loaded image: local/chatdevops:latest [root@ChatDevOps ~]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE local/chatdevops latest dea564c3cb05 3 hours ago 151 MB

本文是Docker官方文档的实例的实践与拓展，刚刚学习Docker，诸多问题还望大家海涵和指教。