Docker error cannot delete docker container, conflict: unable to remove repository reference

Question

I want to remove the container at Docker, but an error occurs when you want to delete

My next step before removing the container, see the list of existing container

sts@Yudi:~/docker$ sudo docker ps -as

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS                    PORTS               NAMES                  SIZE
78479ffeba5c        ubuntu              "/bin/bash"         42 hours ago        Exited (0) 42 hours ago                       sharp_wescoff          81 B (virtual 187.7 MB)
0bd2b54678c7        training/webapp     "python app.py"     5 days ago          Exited (0) 5 days ago                         backstabbing_ritchie   0 B (virtual 323.7 MB)
0adbc74a3803        training/webapp     "python app.py"     5 days ago          Exited (143) 5 days ago                       drunk_feynman          0 B (virtual 323.7 MB)

one I want to delete the list, namely "training / webapp" but an error that occurred

sts@Yudi:~/docker$ sudo docker rmi training/webapp
Error response from daemon: conflict: unable to remove repository reference "training/webapp" (must force) - container 0bd2b54678c7 is using its referenced image 54bb4e8718e8
Error: failed to remove images: [training/webapp]

Whether the container is running in the images?

Please help

Answer 1

There is a difference between docker images and docker containers. Check this SO Question.

In short, a container is a runnable instance of an image. which is why you cannot delete an image if there is a running container from that image. You just need to delete the container first.

docker ps -a                # Lists containers (and tells you which images they are spun from)

docker images               # Lists images 

docker rm <container_id>    # Removes a stopped container

docker rm -f <container_id> # Forces the removal of a running container (uses SIGKILL)

docker rmi <image_id>       # Removes an image 
                            # Will fail if there is a running instance of that image i.e. container

docker rmi -f <image_id>    # Forces removal of image even if it is referenced in multiple repositories, 
                            # i.e. same image id given multiple names/tags 
                            # Will still fail if there is a docker container referencing image

Update for Docker 1.13+ [Since Jan 2017]

In Docker 1.13, we regrouped every command to sit under the logical object it’s interacting with

Basically, above commands could also be rewritten, more clearly, as:

docker container ls -a
docker image ls
docker container rm <container_id>
docker image rm <image_id>

Also, if you want to remove EVERYTHING you could use:

docker system prune -a

WARNING! This will remove:

• all stopped containers
• all networks not used by at least one container
• all unused images
• all build cache