Practice of deploying web applications written in Python with Docker

1. Install Docker
2. Write code
3. Write a Dockerfile
4. Upload the image
5. Modify the image

1. Install Docker

Install docker in WSL2 https://www.jb51.net/article/223179.htm

Will report an error:

# 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

Go to download and install docker under windows

insert image description here

2. Write code

A web server is started using the Flask framework, and its only function is: if there is an environment variable "NAME" in the current environment, it prints it after "Hello", otherwise it prints "Hello world", and finally prints the hostname of the current environment

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()

Export dependency packages

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. Write a Dockerfile

# Use the official Python development image as the base image FROM python:3.8-slim 

# Change the working directory to /app 
WORKDIR /app 

#Copy all the contents in the current directory to /app ADD . /app

# Use pip to install the dependencies required by this application # 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 
# Domestic sources are faster# Allow external access to the container's port 12345 EXPOSE 12345 

# Set environment variable ENV NAME World 

# Set the container process to: python app.py, that is: the startup command of this Python application CMD ["python", "app.py"]
# CMD implicitly includes ENTRYPOINT, /bin/sh -c

insert image description here

In WSL:

Let Docker create an image, add -t tag, automatically load Dockerfile, and execute the statements in it

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 layers 0.6s
 => => 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

View Mirror

(k8s)PC:/mnt/d/gitcode/k8s$ docker image ls
REPOSITORY TAG IMAGE ID CREATED SIZE
helloworld latest 390d32b9f7a2 About a minute ago 169MB

Start the container

docker run -p 4000:12345 helloworld

Because CMD has been specified in the Dockerfile. Otherwise, you have to add the process startup command at the end python app.py

View container startup

(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

-p 4000:12345 tells Docker to map port 12345 in the container to port 4000 on the host machine.

The purpose of this is to access port 4000 of the host machine to see the results returned by the application in the container.

curl http://localhost:4000
# <h3>Hello World!</h3><b>Hostname:</b> dc1c1343e366<br/>

Completed the development and testing of an application using containers

4. Upload the image

docker tag helloworld kobe24o/helloworld:v0

kobe24o is the account name (image repository), helloworld is the image name, and v0 is the version number assigned by itself

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. Modify the image

(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

The above operation adds a new file to the image and commits it to save.

docker inspect --format '{{ .State.Pid}}' dd3bf057cb09
1763
# View the process ID PID of the running container

By viewing the proc file of the host machine, you can see the files corresponding to all Namespaces of this process.

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]'

A process can choose to join the namespace of a certain process, so as to "enter" the container where the process is located. This is exactly the implementation principle of docker exec .

Push to the 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

This is the end of this article about Docker deployment of web applications written in Python. For more relevant content about Docker deployment of Python web applications, please search for previous articles on 123WORDPRESS.COM or continue to browse the following related articles. I hope everyone will support 123WORDPRESS.COM in the future!

You may also be interested in: