製做第一個docker鏡像

首先建立一個新目錄用於存放咱們製做鏡像所需的文件 

進入到新目錄中 執行touch Dockerfile 建立一個Dockerfile文件，Dockerfile 定義了容器運行的須要的環境，網絡端口、磁盤資源、要執行的命令等等。

複製如下內容到Dockerfile中

#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
COPY . /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 8081

# Define environment variable
ENV NAME World

# Run app.py when the container launches
CMD ["python", "app.py"]

在新目錄下執行命令 touch requirements.txt複製如下內容

Flask
Redis

在新目錄下執行命令 touch app.py複製如下內容

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=8081)

執行命令 docker build --tag=helloworld:v0.0.1 . 構建你的第一個docker鏡像，別忘了命令的最後一個. 。

經過下面命令查看您剛剛製做的鏡像

# docker image ls
REPOSITORY           TAG                 IMAGE ID            CREATED             SIZE
helloworld           v0.0.1              f471662fe76e        2 minutes ago       131MB

該鏡像經過Python代碼啓了一個簡單的web服務，下面開始運行您的鏡像

#docker run -p 8099:8081 helloworld:v0.0.1

 * Serving Flask app "app" (lazy loading)
 * Environment: production
   WARNING: This is a development server. Do not use it in a production deployment.
   Use a production WSGI server instead.
 * Debug mode: off
 * Running on http://0.0.0.0:8081/ (Press CTRL+C to quit)

看到上面的輸出說明您的docker 鏡像 helloworld 啓動成功，您能夠經過curl命令測試容器是否正在正常運行，docker run -p 其實是將本地的8099端口映射到容器的8081端口。

# curl http://localhost:8099
<h3>Hello World!</h3><b>Hostname:</b> a64e25c2a522<br/><b>Visits:</b> <i>cannot connect to Redis, counter disabled</i>

您能夠經過一下命令查看當前機器正在運行的容器

# docker container ls
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS                    NAMES
a64e25c2a522        helloworld:v0.0.1   "python app.py"     7 minutes ago       Up 7 minutes        0.0.0.0:8099->8081/tcp   frosty_newton