Naming containers

Learn to name a container with --name.

Naming

If no name is given, Docker generates a random one like jolly_tesla. Giving a meaningful name with --name lets you write later commands without copying IDs. The name must be unique:

$ docker run -d --name db postgres:16
$ docker run -d --name db postgres:16
docker: Error response from daemon: Conflict. The container name "/db" is already in use

Renaming and hostname

docker rename changes the name of an existing container. The hostname seen inside the container is by default the first 12 characters of the ID; it is set with --hostname:

docker rename db db_eski
docker run --rm --hostname derleyici alpine hostname
# derleyici

Exercise Free the name

Write three commands: rename the existing db container to db_eski; start a new container named db from the postgres:16 image in the background with the environment variable POSTGRES_PASSWORD=gizli; list the running containers.

Show example solution

docker rename db db_eski
docker run -d --name db -e POSTGRES_PASSWORD=gizli postgres:16
docker ps

Test yourself

How is the "The container name is already in use" error fixed?
- The old container is removed or a different name is given
- The image is pulled again
- Docker is reinstalled
- The port is changed
Show answer

The old container is removed or a different name is given — A stopped container still keeps its name.

Change the container's name.

docker ____ db db_eski

Show answer

docker rename db db_eski

Match.

--name

Container name
--hostname

Name seen inside
docker rename

Changes the name
jolly_tesla

Random name

Next lesson: Restart policy

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