Minimal dockerizable FastCGI example using Python

.env

COMPOSE_PROJECT_NAME    = example
PYTHON_VER		 = 3

CONTAINER_UID	 = 1000
CONTAINER_GID	 = 1000

SOCKET_UID		 = 1000
SOCKET_GID		 = 33
SOCKET_MODE		 = 660

PUBLIC_SOCKETDIR 	= ./sockets
INTERNAL_SOCKETDIR	= /fcgi-sockets.d/

docker-compose.yml

version: '3.9'
    
services:
  example:
    build:
      context: ./app
      dockerfile: Dockerfile
      args:
        PYTHON_VER:         '${PYTHON_VER}'
        INTERNAL_SOCKETDIR: '${INTERNAL_SOCKETDIR}'
        SOCKET_UID:         '${SOCKET_UID}'
        SOCKET_GID:         '${SOCKET_GID}'
    user: '${CONTAINER_UID}:${CONTAINER_GID}'
    container_name: '${COMPOSE_PROJECT_NAME}'
    restart: unless-stopped
    environment:
      SOCKET_MODE:  '${SOCKET_MODE}'
      SOCKET_DIR:   '${INTERNAL_SOCKETDIR}'
    volumes:
      - ${PUBLIC_SOCKETDIR}:${INTERNAL_SOCKETDIR}

Dockerfile

ARG PYTHON_VER
FROM python:${PYTHON_VER}

WORKDIR /example

COPY example.py /example/example.py

COPY requirements.txt requirements.txt
RUN pip install --no-cache-dir -r requirements.txt

ARG SOCKET_UID  
ARG SOCKET_GID
ARG INTERNAL_SOCKETDIR
RUN (mkdir --mode=u+rwx,g+rs,g-w,o-rwx -p $INTERNAL_SOCKETDIR ) && \
	(chown $SOCKET_UID:$SOCKET_GID $INTERNAL_SOCKETDIR )
# make sure that host directory matches these permissions

CMD [ "python3", "/example/example.py" ]

init.sh

#!/bin/bash

# Load variables from Docker's `.env` file
if [ -f .env ]
then
	export -n $(cat .env | sed -e '/^#/d;/^\s*$/d' -e "s/'/'\\\''/g" -e "s/\t//g" | tr -d ' ' | xargs -d '\n')
fi

# Set permissions for volume mounts

if [ -n "$PUBLIC_SOCKETDIR" ]
then
	mkdir ${PUBLIC_SOCKETDIR}
	chown ${SOCKET_UID}:${SOCKET_GID} ${PUBLIC_SOCKETDIR}
	chmod 6710 ${PUBLIC_SOCKETDIR}
fi

Python_FastCGI_example.py

#!/usr/bin/python3

# ############################################
from fastcgi import *
from pathlib import Path
from socketserver import UnixStreamServer,TCPServer
from warnings import warn
import sys, os, csv

sock_dir  = os.environ.get('SOCKET_DIR', '/fcgi-sockets.d/')
sock_path = f'{sock_dir}/fcgi.sock'
sock_mode = int(os.environ.get('SOCKET_MODE', '660'), 8) # convert to octal
p = Path(sock_path)
if p.exists(): p.unlink()


class FCGIRequestHandler(FcgiHandler):
    def handle(self):
        self.print(f'Content-type: text/html\n\n<h1>Hello {os.getuid()}!</h1>\n')        
        self.print(f'<h4>OS</h4><pre>\n')
        self.print( '\n'.join([f'{k} = {v}' for k, v in os.environ.items()]) )
        self.print(f'</pre><hr><h4>FastCGI::params</h4><pre>\n')
        self.print( '\n'.join([f'{k} = {v}' for k, v in self.environ.items()]) )
        self.print(f'</pre>\n')

with UnixStreamServer(str(p), FCGIRequestHandler) as srv: 
    os.chmod(sock_path, sock_mode)
    srv.serve_forever()

requirements.txt

fastcgi