UP creates a new container as expected but also deletes a previously renamed container

[dkfi]

Given the following YML file:

version: '2'

services:
   db:
      build: .
      container_name: mydb
      restart: always

The image built is a customized postgres:9.6 image. By running "docker-compose up" I end up with a running container named "mydb". I then needed to have an identical container running side-by-side to perform some comparisons: in order to do this I renamed the running container "mydb" to "mydb-old". At this point I would have thought that by running "docker-compose up" with the very same untouched YML file I would've ended up with a fresh "mydb" and the previous "mydb-old" containers running. Instead "docker-compose up" returned

kristian@kristian:~/sandbox/mydb$ docker-compose up -d
Recreating mydb-old

which resulted in the deletion of mydb-old and the recreation of an empty mydb container. Am I missing something?

[shin-]

docker-compose uses labels to identify which containers belong to a project, so changing the container name is not going to "deregister" it.

You could remove the container_name and run docker-compose up; docker-compose scale db=2 if you just need 2 identical containers side by side.

[dkfi]

Thanks for the reply. I guess I was missing something then! ;) Is there a way to deregister a container created with docker-compose for backup purposes? I would like to keep the previous container on the side just in case the new one has problems. Or maybe a better approach?

[shin-]

As I mentioned, docker-compose scale is the best way to do this. Once you don't need the previous container anymore, you can use docker rm directly.

[dkfi]

Great. Thanks for the suggestion @shin- .