pFp - Python, Flask, PostgreSQL

• Python, Flask, PostgreSQL in a Docker Development environment

Prerequisites

• Install and run Docker Desktop
  • https://www.docker.com/get-started

Run Docker images

On the command line (the terminal)

• Clone this repository where you want it.

  • git clone

• Change into the directory

• cd pfp

• Change the PostgreSQL account info in the docker-compose.yml file if you want

      POSTGRES_DB: "dbase"
      POSTGRES_USER: "dbuser"
      POSTGRES_PASSWORD: "dbpass"
      PGDATA: "/var/lib/postgresql/data"
  

• The first time you run this, you will need to create a new docker network

  • docker network create traefikNetwork

• Start the container

  • docker-compose up
  • Or run it in the background to free up the terminal
    • docker-compose up -d

• To stop the containers

  • press ctrl-c
  • then run docker-compose down

• View the web pages at http://lvh.me or http://pfp.lvh.me

  • You can also edit the /etc/hosts file to allow for using existing domain names. For example, add 127.0.0.1 example.com to your /etc/hosts file (Linux or Mac), or c:\windows\system32\drivers\etc\hosts (Windows). Now you can browse to http://example.com .

• View pgAdmin at http://pga.lvh.me

  • After start up, log into pgAdmin with credentials:
    • username: dbuser@pgadmin.com
    • password: dbpass
    • This can be changed in the docker-compose.yml file

        PGADMIN_DEFAULT_EMAIL: "dbuser@pgadmin.com"
        PGADMIN_DEFAULT_PASSWORD: "dbpass"
      

  • Select the 'Add New Server' button.
  • Fill out the field for 'Name'.
  • Select the 'Connection' tab, and fill out 'Host' with postgres, 'Password' with dbpass, and check the 'Save Password' box.
  • Click the 'Save' button
  • The dbase database is now available.
  • type in the db user name and db password to log in

Database Connection

• Connect to the PostgreSQL database with the following credentials:

    POSTGRES_DB: "dbase"
    POSTGRES_USER: "dbuser"
    POSTGRES_PASSWORD: "dbpass"
    url: "postgresql://dbuser:dbpass@postgres:5432/dbase"
  
  

  • The server/host/database url is 'postgres' which is the name of the PostgreSQL container. Because the Python/Flask and PostgreSQL are all in containers, they know to connect to each other through shortcut network names.

Environment Variables

You can set environment variables in the docker-compose.yml file and have them available in the Flask app.

Add Environment variables to the Flask container

  flask:
    build:
      context: .
    depends_on:
      - "traefik"
      - "postgres"
    environment:
      SECRET_KEY: "put_your_secrets_here"
    volumes:
      - "./webapp:/webapp/"
    labels:
      - "traefik.enable=true"
      - "traefik.http.services.flask.loadbalancer.server.port=80"
      - "traefik.http.routers.flask.rule=Host(`localhost`, `lvh.me`, `pfp.lvh.me`, `example.com`)"
      - "traefik.http.routers.flask.entrypoints=web"

Access them in the Flask app

Add import os to the top of the app.py file.

Then add this line after the app = Flask(__name__) line.

app.config['SECRET_KEY'] = os.getenv('SECRET_KEY')

General Notes

• This will run four containers: a proxy container, a Python/Flask container, a PostgreSQL container and a pgAdmin container.
• All of the files for the website building can go in the webapp folder.
• The database files are stored in the db-data folder. This allows for the data to persist between restarts and for hands on access.
  • To restart with a clean database, just delete this folder.
  • To seed the database with a database, tables, and data, just uncomment the line in the docker-compose.yml file referencing postgres_seed.sql. The db-data folder will need to be deleted first. This works best if using a postgres dump file. Otherwise, the sql file just needs to have valid SQL statments.
    • #- ./postgres_seed.sql:/docker-entrypoint-initdb.d/postgres_seed.sql
• You can view the console output of any of the containers by using the command:
  • docker logs -f <container name>

Traefik Notes

This uses the Traefik image from here: https://hub.docker.com/_/traefik/

• Documentation is here: https://doc.traefik.io/traefik/
• You can have multiple domains and subdomains pointing to a single container using the Hosts line in the label section of docker-compose.yml
  • "traefik.http.routers.flask.rule=Host(lvh.me, fun.lvh.me, realdomain.com)"

lvh.me Notes

lvh.me is a free service that redirects to localhost, so now you can access the site at http://lvh.me instead of http://localhost