Not picking up password from linked mysql container

[guidodobboletta]

According to the documentation Docker Hub:

-e WORDPRESS_DB_PASSWORD=... (defaults to the value of the MYSQL_ROOT_PASSWORD environment variable from the linked mysql container)

I have this docker-compose file that should work but it doesn't. When trying to configure wordpress it still asks me for all my database information.

After adding WORDPRESS_DB_PASSWORD to the wordpress service it actually works.

It seems that the linked container code is not working at all, I've also had a look at the entrypoint script for the wordpress:php7.0 image and couldn't find any reference to MYSQL_ROOT_PASSWORD neither on this entire github repo.

This is my compose file:

version: '3.7' 
services:     
  wordpress:   
   image: 'wordpress:php7.0' 
   ports: 
    - '5000:80'
   links:
     - mariadb:mysql

  mariadb:
   image: 'mariadb'
   ports:
    - '3306:3306'
   volumes: 
     - mariadb:/var/lib/mysql
   environment:
     - MYSQL_ROOT_PASSWORD=tmr

volumes:
  mariadb:

[wglambert]

By linked the docs are specifying the --link option to docker run

For containers on the same network the env var values need to be supplied to wordpress

[guidodobboletta]

What's the difference ? Isn't docker-compose also linking the containers the same way docker run would?

https://docs.docker.com/compose/compose-file/#links

[wglambert]

By default Compose sets up a single network for your app. Each container for a service joins the default network and is both reachable by other containers on that network, and discoverable by them at a hostname identical to the container name.
https://docs.docker.com/compose/networking/

Docker also has a linking system that allows you to link multiple containers together and send connection information from one to another. When containers are linked, information about a source container can be sent to a recipient container. This allows the recipient to see selected data describing aspects of the source container.
https://docs.docker.com/network/links/#connect-with-the-linking-system

--link is soft-deprecated, it still provides functionality that Docker networks don't and we use it as an example in the docs to easily demonstrate connectivity without detailing network creation/deletion.

[guidodobboletta]

Ah I see. So I'll have to provide the environment variables to worpdress directly. Sorry for the confusion and thanks for the explanation!

[wglambert]

Docker-compose does support links if you want https://docs.docker.com/compose/networking/#links

[guidodobboletta]

That's what I'm already doing but it's not working. You can see my original comment with my docker-compose config

[wglambert]

Apparently if the containers are on a network, the information from using a --link isn't shared, and since docker-compose creates a network by default; that link functionality doesn't work for it.

[dwasss]

I have the same problem but I'm using depends_on and a custom network to connect the containers together. The generated root password is not being passed to the WordPress container so it cannot log in.

[tianon]

Correct -- that's the expected behavior. Environment variables are only automatically shared with --link, and only when using the default bridge network. You will need to specify the password environment variable on your WordPress container directly.

[dwasss]

That's unfortunate :/ I will try the 2nd solution mentioned in https://stackoverflow.com/questions/39706385/is-it-possible-to-generate-a-random-mysql-password-with-dockercompose.

---

Meh, I ran into issues with the solution above due to use of sudo with docker and complications with environment variables. I will just put a random password in the docker-compose file...