[Docker入门-2] Docker Containers 的创建和使用

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Dockerfile

• Dockerfile 定义了容器内部环境，虚拟了网络、存储等资源，该环境与系统的其他部分隔离。外部访问服务资源时，Dockerfile会说明需要“复制”到哪些文件哪些环境

创建Dockerfile

vi Dockerfile

文件内容如下：

# 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 80

# Define environment variable
ENV NAME World

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

Dockerfile文件中包含了app.py和requirements.txt文件（说明即将进行哪些操作）

app.py文件内容

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 = "cannot connect to Redis, counter disabled"

    html = "
Hello {name}!
" \
           "Hostname: {hostname}
" \
           "Visits: {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)

requirements.txt文件内容

Flask
Redis

内容如下：

创建一个Docker镜像

docker build --tag=friendlyhello .

运行应用

docker run -p 4000:80 friendlyhello

访问：http://localhost:4000/