入门-container-最底层

最底层是container，第二层是service，最高层是stack。

前提

• dockers version:1.13或者更高(17.03.1-ce)

用Dockerfile定制container

dockerfile定义了container的环境里面的内容。在container里面的资源(如网络接口和磁盘驱动)都是虚拟的，和物理机分离的，所以必须映射端口、指定要copy的文件。

创建一个空目录，创建一个Dockerfile文件。

# Use an official python runtime as a base 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 -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"]

需要在container中运行的App

在Dockerfile的同级目录中添加两个文件：requirements.txt和app.py。

Dockerfile中的ADD命令将这两个文件存放在image中，EXPOSE命令可以让我们通过HTTP访问。

requirements.txt

Flask
Redis

app.py

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)

在一个container中获取hostname得到的是container ID。

构建这个app

docker build -t friendlyhello .

运行app

docker run -p 4000:80 friendlyhello

docker run -d -p 4000:80 friendlyhello

docker ps

docker stop 1fa4ab2cf395

分享image

A registry is a collection of repositories, and a repository is a collection of images.

登陆docker id

docker login

给image打标签

本地image和一个registry中的一个repository建立联系的标记为username/repository:tag。

docker tag friendlyhello john/get-started:part1

发布image

docker push username/repository:tag

从远程仓库获取image

docker run -p 4000:80 username/repository:tag

在构建和运行image的时候，如果没有指定:tag，将会使用:latest。运行的时候如果没有tag则运行:latest的版本(不见得是最新的版本)。

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 ps                                 # See a list of all running containers
docker stop <hash>                     # Gracefully stop the specified container
docker ps -a           # See a list of all containers, even the ones not running
docker kill <hash>                   # Force shutdown of the specified container
docker rm <hash>              # Remove the specified container from this machine
docker rm $(docker ps -a -q)           # Remove all containers from this machine
docker images -a                               # Show all images on this machine
docker rmi <imagename>            # Remove the specified image from this machine
docker rmi $(docker images -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