Docker workshop 2

app.py

#!/usr/bin/env python3
from flask import Flask
import os

app = Flask(__name__)

class EnvNotSetError(Exception):
    def __repr__(self):
        return "EnvNotSetException was raised."
    pass


def getMessage():
    configfile = os.getenv("APPCONFIG")
    if not configfile:
        raise EnvNotSetError()
        
    with open(configfile, "r") as f:
        lines=[x[8:].strip() for x in f.readlines() if x.startswith("Message=")]

    return lines[0]



@app.route("/")
def index():
    try:
        message = getMessage()
    except FileNotFoundError:
        message = "CONFIGURATION FILE NOT FOUND! THIS IS NOT OK!"
    except IndexError:
        message = "CONFIGURATION FILE FOUND BUT NO MESSAGE! THIS IS NOT OK!"
    except EnvNotSetError:
        message = "ENVIRONMENT VARIABLE NOT SET! THIS IS NOT OK!"
    except Exception as ex:
        message = f"BIG ERROR: {ex}"

    return f"Hello! I have a Message for you. It reads:\n\n{message}"

app.run(host="0.0.0.0", port=3000, debug=True)

config.msg

Message=Hello from the other side!

docker-compose.yml

version: "3.9"
services:
  app:
    build: .
    ports:
      - "3000:3000"

Dockerfile

FROM ubuntu

RUN apt update -y && apt install -y python3 python3-pip && pip install flask

ENV APPCONFIG=/app/config.msg
ADD config.msg /app/config.msg

ADD app2.py /app/app.py

WORKDIR /app
CMD python3 app.py