Untagging image not working

sw00choi commented 7 years ago

If there are multiple tags for an image, "docker rmi " should untag the given tag from the image. But, when i try to untag from the image, error occurs like this:

> docker images
REPOSITORY                TAG                 IMAGE ID            CREATED             SIZE
ubuntu                    latest              56465e1e45d2        4 weeks ago         0 B

> docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS               NAMES
bf26aabdf1e1        ubuntu              "/bin/sh -c 'while tr"   2 minutes ago       Up 3 minutes                            myubuntu

> docker tag ubuntu ubuntu:newtag

> docker images
REPOSITORY                TAG                 IMAGE ID            CREATED             SIZE
ubuntu                    newtag              56465e1e45d2        4 weeks ago         0 B
ubuntu                    latest              56465e1e45d2        4 weeks ago         0 B

> docker rmi ubuntu:newtag
Error response from daemon: Conflict, cannot delete ubuntu:newtag because the running container bf26aabdf1e1 is using it, stop it and use -f to force (05edbea0-aa3e-11e6-97d4-9f4f8deb19ed)

tgross commented 7 years ago

Check via docker ps -a that you don't have a stopped container bf26aabdf1e1 with that tag.

sw00choi commented 7 years ago

I tested again like this.

I have an image and a container.

> docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
ubuntu              latest              56465e1e45d2        4 weeks ago         0 B

> docker ps -a
CONTAINER ID        IMAGE               COMMAND                  CREATED              STATUS              PORTS               NAMES
8364d05b7aea        ubuntu              "/bin/sh -c 'while tr"   About a minute ago   Up About a minute                       myubuntu

Then, I tagged the image like this:

> docker tag ubuntu:latest ubuntu:atag
> docker tag ubuntu:latest ubuntu:btag
> docker tag ubuntu:latest ubuntu:ctag

> docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
ubuntu              atag                56465e1e45d2        4 weeks ago         0 B
ubuntu              btag                56465e1e45d2        4 weeks ago         0 B
ubuntu              ctag                56465e1e45d2        4 weeks ago         0 B
ubuntu              latest              56465e1e45d2        4 weeks ago         0 B

The IMAGE column of the result from docker ps -a is changed to ubuntu:atag. (It seems that docker ps -a picks the first tag from the image's alphabetically ordered tag list. Some user might be confused because it looks like the image of the running container has been changed. But I don't think it's a big problem.)

> docker ps -a
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS               NAMES
8364d05b7aea        ubuntu:atag         "/bin/sh -c 'while tr"   3 minutes ago       Up 3 minutes                            myubuntu

I want to untag ubuntu:atag, ubuntu:btag, and ubuntu:ctag from the image, but error occurs as follows:

> docker rmi ubuntu:atag
Error response from daemon: Conflict, cannot delete ubuntu:atag because the running container 8364d05b7aea is using it, stop it and use -f to force (fc16b0c0-aaca-11e6-92c6-73e360e212e3)

> docker rmi ubuntu:btag
Error response from daemon: Conflict, cannot delete ubuntu:btag because the running container 8364d05b7aea is using it, stop it and use -f to force (ffadba30-aaca-11e6-92c6-73e360e212e3)

> docker rmi ubuntu:ctag
Error response from daemon: Conflict, cannot delete ubuntu:ctag because the running container 8364d05b7aea is using it, stop it and use -f to force (015576c0-aacb-11e6-92c6-73e360e212e3)

I could not get rid of any of those until I remove the container. It means that before I remove any tag, all containers using the image should be removed.

tgross commented 7 years ago

(It seems that docker ps -a picks the first tag from the image's alphabetically ordered tag list. Some user might be confused because it looks like the image of the running container has been changed. But I don't think it's a big problem.)

That is the behavior of the upstream Docker implementation too (or at least was at one point). I agree that it's weird.

I could not get rid of any of those until I remove the container. It means that before I remove any tag, all containers using the image should be removed.

I can confirm the behavior you're seeing and the upstream Docker implementation doesn't match this. There's an open JIRA DOCKER-163 that refers to this commit https://github.com/joyent/sdc-docker/commit/51a1e2f where the behavior was implemented; it looks like we're not hitting this branch. I'll add a note to this in the open JIRA ticket and ping @twhiteman here.

Some workarounds in the meantime:

Option 1

You can delete all the tags associated with the image via docker rmi -f <short ID>. The container will remain behind.

docker rmi -f a46650c13b46
Untagged: alpine:c
Untagged: alpine:b
Untagged: alpine:a
Untagged: alpine:latest
Deleted: a46650c13b46891f6d1cfc601acca45087ec4031df57b5bc06ea689330d694d7

Option 2

You can update the tag you want to delete to point to an image that you're not running a container for.

$ docker pull alpine:3.3
3.3: Pulling from alpine (req e78a60b0-ab39-11e6-a0a4-29f42d73db17)
ce2f9b63043b: Pull complete
Digest: sha256:75a6050d5237f432391a0e3fac37b44ee5b5c78158868a68cfaaf72e872a2176
Status: Downloaded newer image for alpine:3.3

$ docker pull alpine:latest
latest: Pulling from alpine (req ea7fd2f0-ab39-11e6-a0a4-29f42d73db17)
a46650c13b46: Already exists
Digest: sha256:fb76bd8c78f158a05b2d7b3ad624d4be0d094c6645a5c713883eb6af47553881
Status: Image is up to date for alpine:latest

$ docker tag alpine:latest alpine:atag
$ docker tag alpine:latest alpine:btag
$ docker tag alpine:latest alpine:ctag

$ docker run --name test1 alpine:ctag exit 1
$ docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS                      PORTS               NAMES
a07fe6b45c1b        alpine              "exit 1"            28 seconds ago      Exited (17) 8 seconds ago                       test1

$ docker rmi alpine:ctag
Error response from daemon: Conflict, cannot delete alpine:latest because the container a07fe6b45c1b is using it, use -f to force (2dfd0bb0-ab3a-11e6-a0a4-29f42d73db17)

$ docker tag alpine:3.3 alpine:c

$ docker rmi alpine:c
Untagged: alpine:c

$ docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS                      PORTS               NAMES
a07fe6b45c1b        alpine              "exit 1"            2 minutes ago       Exited (17) 2 minutes ago                       test1

twhiteman commented 7 years ago

Thanks - logging this as a bug here https://smartos.org/bugview/DOCKER-975, which should be fixed soon. Closing this issue.

twhiteman commented 7 years ago

Didn't realize sw00choi had already started a CR for this, so re-opening: https://cr.joyent.us/#/c/890/

twhiteman commented 7 years ago

Fixed by @sw00choi - thanks!

TritonDataCenter / sdc-docker

Untagging image not working #95