Dockerize a Flaskapp - Python

Question

I need help Dockerizing an app.

Following is my requirements.txt:

Flask==0.12
flask-redis==0.3

And this is my app.py:

import os

from flask import Flask
from flask_redis import FlaskRedis

app = Flask(__name__)
app.config['REDIS_URL'] = 'redis://redis:6379/0'

redis = FlaskRedis(app)

@app.route('/')
def counter():
    return '{0} {1} {2}'.format('This webpage has been viewed',str(redis.incr('web2_counter')),' time(s).')

I've created my Dockerfile like this:

FROM python:3.6-stretch

# We don't want to run our application as root if it is not strictly necessary, even in a container.
# Create a user and a group called 'app' to run the processes.
# A system user is sufficient and we do not need a home.
RUN adduser --system --group --no-create-home app


# Place the application components in a dir below the root dir
COPY . /app

# Make the directory the working directory for subsequent commands
WORKDIR /app


# Install from the requirements.txt we copied above
RUN pip install -r requirements.txt --no-cache-dir


# Hand everything over to the 'app' user
RUN chown -R app:app /app


# Subsequent commands, either in this Dockerfile or in a
# docker-compose.yml, will run as user 'app'
USER app

COPY . .

and my docker-compose.yml:

version: '3'

services:

  web:
     build: .
     command: flask run --host=0.0.0.0 --port=5000
     ports:
        - "5000:5000"
     environment:
      - FLASK_APP=app.py
      - FLASK_DEBUG=1
     volumes:
        - .:/app
     depends_on:
        - redis

  redis:
    image: "redis:alpine"
    ports:
      - '6379:6379'

The redis container starts as normal, but not the web. Getting below error:

"Traceback (most recent call last):
  File "/usr/local/bin/flask", line 5, in <module>
    from flask.cli import main
    ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/flask/__init__.py", line 19, in <module>
    from jinja2 import Markup, escape
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ImportError: cannot import name 'Markup' from 'jinja2' (/usr/local/lib/python3.11/site-packages/jinja2/__init__.py)"

Expected result: curl localhost:5000

This webpage has been viewed N time(s)

Can someone point me to the right direction?

[ImportError cannot import name Markup from jinja2](https://stackoverflow.com/questions/71645272/importerror-cannot-import-name-markup-from-jinja2) — Esther, Jun 23 '22 at 21:13
try running "USER app" before pip install. because pip normally install stuff to a user directory. so by switching it you can no longer see the pip installations. or remove the user stuff for testing to see if it will work — Furkan, Jun 23 '22 at 21:19

score 1 · Accepted Answer · answered Jun 23 '22 at 21:27

1

Your requirements.txt should contain all needed requirements. Something like this

Flask==1.1.1
Jinja2==2.11.3
MarkupSafe==2.0.1
itsdangerous==1.1.0
Werkzeug==2.0.2
flask-redis==0.3

answered Jun 23 '22 at 21:27

Jishnu Ramesh

617
10
17

Why do i need `Jinja2` etc? – kabax Jun 23 '22 at 21:38
I will point you to original flask documentation. Jinja2 is the templating engine for Flask. The way project is structured and imports works means you will need to install it regardless whether you use it or not https://flask.palletsprojects.com/en/2.1.x/templating/#templates – Jishnu Ramesh Jun 23 '22 at 22:00

Dockerize a Flaskapp - Python

1 Answers1