環境

• Mac M1
• docker:Version 20.10.11

1. 建立app.py

from flask import Flask
from redis import Redis
import os
import socket

app = Flask(__name__)
redis = Redis(host=os.environ.get('REDIS_HOST', '127.0.0.1'), port=6379)


@app.route('/')
def hello():
    redis.incr('hits')
    return f"Hello Container World! I have been seen {redis.get('hits').decode('utf-8')} times and my hostname is {socket.gethostname()}.\n"

2. 同一層建立dockerfile

FROM python:3.9.5-slim

RUN pip install flask redis && \
    groupadd -r flask && useradd -r -g flask flask && \
    mkdir /src && \
    chown -R flask:flask /src

USER flask

COPY app.py /src/app.py

WORKDIR /src

ENV FLASK_APP=app.py REDIS_HOST=redis

EXPOSE 5000

CMD ["flask", "run", "-h", "0.0.0.0"]

3. image 的準備

$ docker image pull redis
$ docker image build -t flask-demo .
$ docker image ls
REPOSITORY   TAG       IMAGE ID       CREATED         SIZE
flask-demo   latest    d92f7778af76   9 minutes ago   123MB
redis        latest    f16c30136ff3   4 weeks ago     107MB

4. 創建一個docker bridge

$ docker network create -d bridge demo-network
960a617c97c6a197624c51fc02dbbf9007080662052551296d55b0cc7d5f2ba7
$ docker network ls
NETWORK ID     NAME           DRIVER    SCOPE
b2077f8151cb   bridge         bridge    local
caf0f586ef79   demo-network   bridge    local
d1465da885e1   host           host      local

5. 創建redis container
   創建一個叫 redis-server 的container，連到demo-network上

$ docker container run -d --name redis-server --network demo-network redis
960a617c97c6a197624c51fc02dbbf9007080662052551296d55b0cc7d5f2ba7

$ docker container ls
CONTAINER ID   IMAGE        COMMAND                  CREATED          STATUS          PORTS                    NAMES
960a617c97c6   redis        "docker-entrypoint.s…"   12 minutes ago   Up 12 minutes   6379/tcp                 redis-server

6. 創建flask container

$ docker container run -d --network demo-network --name flask-demo --env REDIS_HOST=redis-server -p 5000:5000 flask-demo

7. 打開瀏覽器

輸入:

127.0.0.1:5000

會看到下圖，每次刷新頁面，計數加1:ㄋ

Hello Container World! I have been seen 2 times and my hostname is a426b16a8d01.

總結

如果把上面的步驟合併到一起，成為一個部署腳本:

# prepare image
docker image pull redis
docker image build -t flask-demo .

# create network
docker network create -d bridge demo-network

# create container
docker container run -d --name redis-server --network demo-network redis
docker container run -d --network demo-network --name flask-demo --env REDIS_HOST=redis-server -p 5000:5000 flask-demo