Docker部署用Python編寫(xiě)的Web應(yīng)用的實(shí)踐
1. 安裝 docker
在 WSL2 中安裝 docker https://www.jb51.net/article/223179.htm
會(huì)報(bào)錯(cuò)：
# Executing docker install script, commit: 93d2499759296ac1f9c510605fef85052a2c32be
WSL DETECTED: We recommend using Docker Desktop for Windows.
Please get Docker Desktop from https://www.docker.com/products/docker-desktop
You may press Ctrl+C now to abort this script.
+ sleep 20
去下載安裝 windows 下的 docker
2. 編寫(xiě)代碼
使用 Flask 框架啟動(dòng)了一個(gè) Web 服務(wù)器，而它唯一的功能是：如果當(dāng)前環(huán)境中有 “NAME” 這個(gè)環(huán)境變量，就把它打印在 “Hello” 后，否則就打印 “Hello world”，最后再打印出當(dāng)前環(huán)境的 hostname
import os
from flask import Flask
import socket
from gevent import pywsgi
app = Flask(__name__)
@app.route('/')
def hello():
html = "<h3>Hello {name}!</h3>" \
"<b>Hostname:</b> {hostname}<br/>"
return html.format(name=os.getenv("NAME", "world"), hostname=socket.gethostname())
if __name__ == "__main__":
server = pywsgi.WSGIServer(('0.0.0.0', 12345), app)
server.serve_forever()
導(dǎo)出依賴(lài)包
pip freeze >requirements.txt
Flask==2.0.1 gevent==21.8.0 greenlet==1.1.1 itsdangerous==2.0.1 Jinja2==3.0.1 MarkupSafe==2.0.1 Werkzeug==2.0.1 zope.event==4.5.0 zope.interface==5.4.0
3. 編寫(xiě) Dockerfile
# 使用官方提供的 Python 開(kāi)發(fā)鏡像作為基礎(chǔ)鏡像 FROM python:3.8-slim # 將工作目錄切換為 /app WORKDIR /app # 將當(dāng)前目錄下的所有內(nèi)容復(fù)制到 /app 下 ADD . /app # 使用 pip 命令安裝這個(gè)應(yīng)用所需要的依賴(lài) # RUN pip install --trusted-host pypi.python.org -r requirements.txt RUN pip install --trusted-host https://pypi.tuna.tsinghua.edu.cn/simple -r requirements.txt # 國(guó)內(nèi)的源更快 # 允許外界訪(fǎng)問(wèn)容器的 12345 端口 EXPOSE 12345 # 設(shè)置環(huán)境變量 ENV NAME World # 設(shè)置容器進(jìn)程為：python app.py，即：這個(gè) Python 應(yīng)用的啟動(dòng)命令 CMD ["python", "app.py"] # CMD 前面 隱式的包含了 ENTRYPOINT ， /bin/sh -c
在 WSL 里操作 ：
讓 docker 制作鏡像，-t 加 tag，自動(dòng)加載 Dockerfile，執(zhí)行里面的語(yǔ)句
docker build -t helloworld .
[+] Building 17.4s (10/10) FINISHED => [internal] load build definition from Dockerfile 0.1s => => transferring dockerfile: 757B 0.0s => [internal] load .dockerignore 0.1s => => transferring context: 2B 0.0s => [internal] load metadata for docker.io/library/python:3.8-slim 2.9s => [auth] library/python:pull token for registry-1.docker.io 0.0s => [1/4] FROM docker.io/library/python:3.8-slim@sha256:4dd66d1ccaddaa0587851cb92b365bf3090dccb41393c6f8b 0.0s => [internal] load build context 0.1s => => transferring context: 813B 0.0s => CACHED [2/4] WORKDIR /app 0.0s => [3/4] ADD . /app 0.1s => [4/4] RUN pip install --trusted-host https://pypi.tuna.tsinghua.edu.cn/simple -r requirements.txt 13.6s => exporting to image 0.6s => => exporting layers0.6s => => writing image sha256:390d32b9f7a20ccd347361bd31450807d3e63d052e334865cf8460968ffceff4 0.0s => => naming to docker.io/library/helloworld 0.0s Use 'docker scan' to run Snyk tests against images to find vulnerabilities and learn how to fix them
查看鏡像
(k8s)PC:/mnt/d/gitcode/k8s$ docker image ls REPOSITORY TAG IMAGE ID CREATED SIZE helloworld latest 390d32b9f7a2 About a minute ago 169MB
啟動(dòng)容器
docker run -p 4000:12345 helloworld
因?yàn)樵?Dockerfile 中已經(jīng)指定了 CMD。否則，就得把進(jìn)程的啟動(dòng)命令加在后面 python app.py
查看容器啟動(dòng)
(base) $ docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES f6e051d1af6b helloworld "python app.py" 2 minutes ago Up 2 minutes 0.0.0.0:4000->12345/tcp, :::4000->12345/tcp upbeat_elion
通過(guò) -p 4000:12345 告訴 Docker，把容器內(nèi)的 12345 端口映射在宿主機(jī)的 4000 端口上
這樣做的目的是，只要訪(fǎng)問(wèn)宿主機(jī)的 4000 端口，就可以看到容器里應(yīng)用 返回的結(jié)果
curl http://localhost:4000 # <h3>Hello World!</h3><b>Hostname:</b> dc1c1343e366<br/>
使用容器完成了一個(gè)應(yīng)用的開(kāi)發(fā)與測(cè)試
4. 上傳鏡像
注冊(cè) docker hub，docker login 命令登錄
docker tag helloworld kobe24o/helloworld:v0
kobe24o 是賬號(hào)名（鏡像倉(cāng)庫(kù)），helloworld 鏡像名，v0自己分配的版本號(hào)
docker push kobe24o/helloworld:v0
(k8s) $ docker push kobe24o/helloworld:v0 The push refers to repository [docker.io/kobe24o/helloworld] 931022d457d6: Pushing [================> ] 16.07MB/47.27MB c76dc68917fc: Pushed 047ca6dfe9ab: Pushed d82f4c466b47: Mounted from library/python 5aa75f4e55e7: Mounted from library/python 74d6903a940b: Mounted from library/python 2f9c2b8e82bd: Mounted from library/python ba5a5fe43301: Mounted from library/python
5. 修改鏡像
(base) $ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS
NAMES
dd3bf057cb09 helloworld "python app.py" 7 seconds ago Up 5 seconds 0.0.0.0:4000->12345/tcp, :::4000->12345/tcp compassionate_carver
(base) $ docker exec -it dd3bf057cb09 /bin/sh
# pwd
/app
# touch newfile.txt
# ls
Dockerfile app.py newfile.txt requirements.txt
# exit
(base) $ docker commit dd3bf057cb09 kobe24o/helloworld:v1
sha256:ca8880f84040f9bdd7ef13763b9c64f8bd4a513a74bc2b095be06aae5b60268a
上面操作，新加了一個(gè)文件到鏡像里，commit 保存
docker inspect --format '{{ .State.Pid}}' dd3bf057cb09
1763
# 查看正在運(yùn)行的容器的進(jìn)程號(hào) PID
通過(guò)查看宿主機(jī)的 proc 文件，看到這個(gè) 進(jìn)程的所有 Namespace 對(duì)應(yīng)的文件
root:/# ls -l /proc/{PID}/ns/
total 0
lrwxrwxrwx 1 root root 0 Sep 14 11:15 cgroup -> 'cgroup:[4026531835]'
lrwxrwxrwx 1 root root 0 Sep 14 11:15 ipc -> 'ipc:[4026532220]'
lrwxrwxrwx 1 root root 0 Sep 14 09:49 mnt -> 'mnt:[4026532218]'
lrwxrwxrwx 1 root root 0 Sep 14 11:15 net -> 'net:[4026531992]'
lrwxrwxrwx 1 root root 0 Sep 14 11:15 pid -> 'pid:[4026532221]'
lrwxrwxrwx 1 root root 0 Sep 14 11:15 pid_for_children -> 'pid:[4026532221]'
lrwxrwxrwx 1 root root 0 Sep 14 11:15 user -> 'user:[4026531837]'
lrwxrwxrwx 1 root root 0 Sep 14 11:15 uts -> 'uts:[4026532219]'
一個(gè)進(jìn)程，可以選擇 加入 到某個(gè)進(jìn)程已有的 Namespace 當(dāng)中，從而達(dá)到 “進(jìn)入” 這個(gè)進(jìn)程所在容器的目的，這正是 docker exec 的實(shí)現(xiàn)原理
push 到 hub
(base) $ docker push kobe24o/helloworld:v1 The push refers to repository [docker.io/kobe24o/helloworld] dfee38b42dbb: Pushed 931022d457d6: Layer already exists c76dc68917fc: Layer already exists 047ca6dfe9ab: Layer already exists d82f4c466b47: Layer already exists 5aa75f4e55e7: Layer already exists 74d6903a940b: Layer already exists 2f9c2b8e82bd: Layer already exists ba5a5fe43301: Layer already exists v1: digest: sha256:7af7ff571ea9fd70d48abeaa2b38a1ed1c1a4e5a933b722d82af25d3e889f84e size: 2206
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