前言

接上篇，我们已经把docker的环境搭建完毕。下面将按官网的教程进行相关的入门操手。官网的教程地址：Get Started, Part 2: Containers

Dockerfilew配置容器

在宿主机上建立一个目录如demo-docker
cd demo-docker
vi Dockerfile
在文件中录入如下内容：

# Use an official Python runtime as a parent image
# 我们使用官方提供的Python运行库作为父镜像
FROM python:2.7-slim

# Set the working directory to /app
# 设置工程目录路径 /app
WORKDIR /app

# Copy the current directory contents into the container at /app
# 复制当前文件夹下的文件到工程路径 /app下
ADD . /app

# Install any needed packages specified in requirements.txt
# 安装在requirements.txt中列出的依赖包
RUN pip install --trusted-host pypi.python.org -r requirements.txt

# Make port 80 available to the world outside this container
# 对外暴露本容器80端口
EXPOSE 80

# Define environment variable
# 定义环境变量
ENV NAME World

# Run app.py when the container launches
# 当容器运行时，执行的命令
CMD ["python", "app.py"]

vi requirements.txt，并录入如下内容

Flask
Redis

vi app.py 并录入如下内容

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)

最后在demo-docker中将有如下文件

app.py  Dockerfile  requirements.txt

创建docker镜像

docker build -t demo-docker .

运行完毕后，我们查看一下系统存在的docker镜像

docker image ls
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
demo-docker         latest              321a0064dbe2        About an hour ago   148MB
python              2.7-slim            b0259cf63993        7 days ago          138MB
hello-world         latest              725dcfab7d63        8 days ago          1.84kB

运行我们的镜像

# 将本机的4000端口映射到容器的80端口
docker run -p 4000:80 demo-docker

在后台运行

docker run -d -p 4000:80 demo-docker

启动后我们将得到容器的ID信息，停止的时候，我们将会使用到此ID.另外我们还可以通过命令来查看相关的ID

docker container ls
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS                  NAMES
83dd2473dc19        demo-docker         "python app.py"     7 seconds ago       Up 6 seconds        0.0.0.0:4000->80/tcp   pensive_yalow

停止在后台运行的容器

docker container stop 83dd2473dc19

docker的一些常用命令

docker build -t friendlyname .  # Create image using this directory's Dockerfile
docker run -p 4000:80 friendlyname  # Run "friendlyname" mapping port 4000 to 80
docker run -d -p 4000:80 friendlyname         # Same thing, but in detached mode
docker container ls                                # List all running containers
docker container ls -a             # List all containers, even those not running
docker container stop <hash>           # Gracefully stop the specified container
docker container kill <hash>         # Force shutdown of the specified container
docker container rm <hash>        # Remove specified container from this machine
docker container rm $(docker container ls -a -q)         # Remove all containers
docker image ls -a                             # List all images on this machine
docker image rm <image id>            # Remove specified image from this machine
docker image rm $(docker image ls -a -q)   # Remove all images from this machine
docker login             # Log in this CLI session using your Docker credentials
docker tag <image> username/repository:tag  # Tag <image> for upload to registry
docker push username/repository:tag            # Upload tagged image to registry
docker run username/repository:tag                   # Run image from a registry

一些常见问题

# 当因网络问题，安装一些依赖失败的时候，会发现Docker的镜像并没有构建完成，而且在
docker image ls
中可看到相关的信息。
此时，我们先运行
docker ps -a
如果存在容器，则先把容器给删除掉
docker rm <cotainerID>
再执行
docker rmi <imageID>