版權聲明：本文為博主原創文章，未經博主允許不得轉載。 https://blog.csdn.net/zhaobryant/article/details/79600059

簡介

本文將用Docker的方式來構建一個應用APP。

過去，如果要開發一個Python應用APP，所需做的第一件事就是在開發機上安裝Python運行時環境。在這種情形下，開發機的環境必須與APP所要求的環境一致，同時還需要與生產環境相匹配。

通過使用Docker，可以將一個可移植的Python運行時環境作為一個image獲取，而無需安裝。然后，就可以基于Python運行時環境image，將APP代碼及其依賴庫合并構建，從而簡化了應用APP的部署難度。

用Dockerfile定義容器Container

Dockerfile是由一系列命令和參數構成的腳本，這些命令應用于基礎鏡像并最終創建一個新的鏡像。它簡化了業務部署的流程，大大提高了業務的部署速度。Dockerfile的產出為一個新的可以用于創建容器的鏡像。

Dockerfile語法由兩部分構成，分別是“注釋”和“命令+參數”。

# Line blocks used for commenting COMMAND argument1 argument2 ...

對于Dockerfile，我們首先創建一個空目錄，然后cd到該目錄，并創建Dockerfile文件。

# 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"]

其中，app.py和requirements.txt都位于與Dockerfile相同的目錄下，具體如下：

zjl@ubuntu:~/docker/pyapp$ ls app.py Dockerfile requirements.txt

對于requirements.txt，其內容如下：

Flask Redis

對于app.py，其內容如下：

from flask import Flask from redis import Redis, RedisError import os import socketredis = 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)

現在，我們知道，pip install -r requirements.txt為Python安裝了Flask和Redis庫，同時APP會打印出環境變量NAME，同時將socket.gethostname()打印出來。

構建新的image鏡像

下面，我們進行構建，具體如下：

zjl@ubuntu:~/docker/pyapp$ ls app.py Dockerfile requirements.txtzjl@ubuntu:~/docker/pyapp$ sudo docker build -t fhello . Sending build context to Docker daemon 4.608kB Step 1/7 : FROM python:2.7-slim 2.7-slim: Pulling from library/python d2ca7eff5948: Pull complete cef69dd0e5b9: Pull complete 50e1d7e4f3c6: Pull complete 861e9de5333f: Pull complete Digest: sha256:e9baca9b405d3bbba71d4c3c4ce8a461e4937413b8b910cb1801dfac0a2423aa Status: Downloaded newer image for python:2.7-slim---> 52ad41c7aea4 Step 2/7 : WORKDIR /app ... Step 3/7 : ADD . /app ... Step 4/7 : RUN pip install --trusted-host pypi.python.org -r requirements.txt ... Step 5/7 : EXPOSE 80 ... Step 6/7 : ENV NAME World ... Step 7/7 : CMD ["python", "app.py"] ... Successfully built d3fafd68e807 Successfully tagged fhello:latestzjl@ubuntu:~/docker/pyapp$ sudo docker image ls REPOSITORY TAG IMAGE ID CREATED SIZE fhello latest 12d000cd7a1b 12 minutes ago 148MB

運行新的image鏡像

$ sudo docker run -p 4000:80 fhello* Running on http://0.0.0.0:80/ (Press CTRL+C to quit)# 訪問該網站 $ curl localhost:4000 <h3>Hello World!</h3><b>Hostname:</b> f4e37f061593<br/><b>Visits:</b> <i>cannot connect to Redis, counter disabled</i>$ sudo docker container ls CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 4a150bdc67cd fhello "python app.py" 10 seconds ago Up 9 seconds 0.0.0.0:4000->80/tcp upbeat_austin

關閉容器，命令如下：

$ sudo docker container stop 4a150bdc67cd 4a150bdc67cd

給鏡像打上標簽

syntax: -->> docker tag image username/repository:tag $ sudo docker tag fhello zhjl/getstarted:alpha-1 $ sudo docker image ls REPOSITORY TAG IMAGE ID CREATED SIZE fhello latest 12d000cd7a1b 18 minutes ago 148MB zhjl/getstarted alpha-1 12d000cd7a1b 18 minutes ago 148MB$ docker run -p 4000:80 zhjl/getstarted:alpha-1

Recap and cheat sheet

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

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