sqlalchemy cannot connect to MYSQL server on '127.0.0.1'

Question

I am trying to dockerize powerdns-admin and the app needs connection a database, the database i use is mariadb via sqlalchemy.
The docker-compose:
docker-compose.yml

version: "3"

services:
  app:
    image: ngoduykhanh/powerdns-admin:latest
    container_name: powerdns_admin
    ports:
      - "9191:80"
    logging:
      driver: json-file
      options:
        max-size: 50m
    environment:
      - SQLALCHEMY_DATABASE_URI=mysql://root:[email protected]/powerdns
      - GUNICORN_TIMEOUT=60
      - GUNICORN_WORKERS=2
      - GUNICORN_LOGLEVEL=DEBUG
      - OFFLINE_MODE=False # True for offline, False for external resources

When i run docker-compose up -d it only outputs the following error:

sqlalchemy.exc.OperationalError: (MySQLdb._exceptions.OperationalError) (2002, "Can't connect to MySQL server on '127.0.0.1' (115)")

When i do mysql -uroot -pdbpass from the host of the docker-compose, i can connect successfully.
same when i run the following commands from the mysql host:

mysql -uroot -pdbpass -h 127.0.0.1
mysql -uroot -pdbpass -h localhost

What is wrong?

Asked By: ben shalev

||

Source

Answer 1

When you run a docker container, you it behaves a lot like a separate machine. When you try to connect to 127.0.0.1 you’re trying to connect to the container itself. Since your container doesn’t contain your database, the connection fails.

From inside a container you can reach the host machine on ip address 172.17.0.1. So your database URI should be

SQLALCHEMY_DATABASE_URI=mysql://root:[email protected]/powerdns

Answered By: Hans Kilian

sqlalchemy cannot connect to MYSQL server on '127.0.0.1'

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