When you put an application in a container, something that often breaks is the connection to the database and other services. If you're struggling to get two containers to talk to each other, you can try these 4 troubleshooting steps to quickly fix your issue. In short:

- Containers should be in the same network

- Connecting to a container by its name isn't possible in the default network, create on of your own instead

- Make sure you are using the correct IP address

- The network should have ICC enabled (it does by default)

In the article, I elaborate a little bit more on each bullet point and show you a solution. This isn't a comprehensive list, but hopefully it helps some folks who have already spent several hours debugging their issues.