Cached Docker image? - docker

I created my own image and pushed it to my repo on docker hub. I deleted all the images on my local box with docker rmi -f ...... Now docker images shows an empty list.
But when I do docker run xxxx/yyyy:zzzz it doesn't pull from my remote repo and starts a container right away.
Is there any cache or something else? If so, what is the way to clean it all?
Thank you

I know this is old now but thought I'd share still.
Docker will contain all those old images in a Cache unless you specifically build them with --no-cache, to clear the cache down you can simply run docker system prune -a -f and it should clear everything down including the cache.
Note: this will clear everything down including containers.

You forced removal of the image with -f. Since you used -f I'm assuming that the normal rmi failed because containers based on that image already existed. What this does is just untag the image. The data still exists as a diff for the container.
If you do a docker ps -a you should see containers based on that image. If you start more containers based on that same previous ID, the image diff still exists so you don't need to download anything. But once you remove all those containers, the diff will disappear and the image will be gone.

Related

is it possible recover the deleted docker image

I execute the docker(Docker version 19.03.1, build 74b1e89) clean command in the server:
docker system prune
to my surprise, this command delete the container that stopped. That's the problem, some container stopped by some reason but I still want to use it in the furture. Now it is deleted, is it possible to recover the mistaking deleted container that stopped?
No, it is not possible. You have to repull the image docker pull image, or rebuild the image.
Docker images and containers are not the same. See this answer.
docker system prune tells you:
WARNING! This will remove:
- all stopped containers
- all networks not used by at least one container
- all dangling images
- all dangling build cache
Are you sure you want to continue? [y/N]
So it should be no surprise that it removed your container and possibly also the image it was based on (if no other container was running based on that same image).
I believe it is not possible to recover your image or container, however you can rebuild them. Depending on how the image was obtained you have to run:
docker pull <image> # for an image on dockerhub or other registry
docker build <arguments> # for an image based on a dockerfile
After that you will have your image and you can run a container again with:
docker run <image>

Docker image layer always already exists

I've got this very weird issue where a layer of a docker image always Already exists, even if I remove /var/lib/docker and pull the image again.
The image in question is a simple nginx server containing an Angular webapp. The "already existing" layer is the one containing the webapp. Which means I can't update it at the moment.
FROM nginx:alpine
COPY nginx.conf /etc/nginx/nginx.conf
WORKDIR /usr/share/nginx/html
COPY dist/ .
I've build the image on my local machine and pushed it to the gitlab container registry. I've checked if the image is fine by pulling the image back from the registry. So the issue is clearly with my server.
The server is an ubuntu machine running Docker version 19.03.8, build afacb8b.
How can the layer still exist if I delete /var/lib/docker?
I got stucked at this point ... Any help is highly appreciated.
Update
I think I should extend my question a bit: I've tried all sorts of combinations of removing docker images:
docker rmi with and without force option etc.
docker image prune
docker system prune with and without --all, --volumes options
Like I said above even removing the whole /var/lib/docker directory (while docker service was stopped) didn't solve the issue. In my understanding this is the hard way of removing everything - so to say the brutal way of doing the steps above. But maybe I'm missing something here!?
Before pulling the image after all above measures again, docker images ls -a didn't list any image.
So why is there a single layer left?
cbdbe7a5bc2a: Already exists
10c113fb0c77: Pull complete
9ba64393807b: Pull complete
262f9908119d: Pull complete
to clean all images
docker rmi $(docker images -a --filter=dangling=true -q)
to clean ps
docker rm $(docker ps --filter=status=exited --filter=status=created -q)
after running this 2 commands, everything will be deleted

Docker remove container with changes

How can I remove a container without removing all the changes that have been made in this container?
I already used:
Stop all running containers: docker stop $(docker ps -a -q)
Delete all stopped containers: docker rm $(docker ps -a -q)
You can create a docker image from your container with docker commit.
This image can be used to start up new containers or can be pushed to a docker repository for later use.
https://docs.docker.com/engine/reference/commandline/commit/
You don’t. Anything you change in a Docker container will be lost as soon as the container is deleted. Also, you need to routinely delete containers to change options like the base image (if there’s some security patch you need), networking options, or environment variables.
The standard pattern for this involves two things:
Don’t install software or make other configuration changes inside a running container. Instead, write a Dockerfile that does that work for you, check it into source control, and use docker build to build an image from it. (If you get something wrong, you can easily fix it and re-run it; if you need to update something in six months you have a written record of what you did.)
If your container does need some persistent state, start it with docker run -v or a similar option to mount a host directory or named volume into the container. Data stored there will outlive the container.
In theory docker commit can turn a container into an image, but using it really isn’t a best practice. Images you build this way can’t be recreated or updated (again, imagine a critical security fix in the underlying base image). In some cases a committed container won’t even have the data you want to save (for example you can’t usefully commit a MySQL or PostgreSQL container).

How to make docker reset the image on remote server?

On docker build from jenkins 1st docker images are created tagged properly as LATEST on remote server.
On rebuild it supposed to overwrite docker image on server. But it didn't.
Virtually it creates new docker images with no-tag repository and no-tag tag. And avoid using predefined domain name for image.
So creates a new because it's supposed create NEW image because they are totally different.
Is there any way to avoid just deleting image directly from the remote server? But to update image docker on same tag(domain) name?
Any ideas on workaround? How to avoid making new docker images with static unchanged TAG name from jenkins build.
Because it eats a lot of memory space on the moment when run on cron.
How can I overwrite docker image or make a facade that it's overwrited?
You can delete no-tag images after build image from jenkins by: docker rmi $(docker images -f "dangling=true" -q)

docker pull always show "Already exists" for layers during pull even after deleting all images

here is my input and output:
shshenhx#shshenhx:~/Desktop/Docker$ docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
python latest 336d482502ab 4 days ago 692 MB
shshenhx#shshenhx:~/Desktop/Docker$ docker rmi 336
Untagged: python:latest
Untagged: python#sha256:bf0718e2882cabc144c9c07d758b09c65efc104a6ddc72a9a976f8b26f67c2ee
Deleted: sha256:336d482502ab564b0b2964b2ed037529ba40c7b4ade2117ca11d74edbf11f99e
Deleted: sha256:1e2f72b0bf844de7bfe57a32115b660770355843ef8078fb55629e720147e6a9
Deleted: sha256:b5818ba96f33835318f3e9d7b4094e1007be247f04ab931ea9ef83b45b451f90
Deleted: sha256:0c2d7cafdab1084ebbd0112b3bedf76458ae6809686fb0ad9bae8022f11c3a84
shshenhx#shshenhx:~/Desktop/Docker$ docker pull python
Using default tag: latest
latest: Pulling from library/python
4176fe04cefe: Already exists
851356ecf618: Already exists
6115379c7b49: Already exists
aaf7d781d601: Already exists
40cf661a3cc4: Already exists
975fe2fd635f: Pull complete
bf4db784e7fd: Pull complete
0491f7e9426b: Pull complete
Digest: sha256:bf0718e2882cabc144c9c07d758b09c65efc104a6ddc72a9a976f8b26f67c2ee
Status: Downloaded newer image for python:latest
My question is, I have already rm python image, why it still shows already exist for some of layers? How can I totally delete all the python layers.
Thanks.
What helped for me was to run docker-system prune after removing all containers and images. So the whole process I got it to work was:
Remove all containers docker rm -vf $(docker ps -a -q)
Remove all images docker rmi -f $(docker images -a -q)
Prune system with docker system prune
From reference of docker images command
Docker images have intermediate layers that increase reusability, decrease
disk usage, and speed up docker build by allowing each step to be cached.
These intermediate layers are not shown by default.
Maybe those Already exists are intermediate layers. By default, they are hided when you run docker images, please try docker images --all.
Docker has a solution for this on docker dashboard, just press the button below and presto it works! (This is in the troubleshooting section. or the bug icon)
There is a docker command that deletes images that do not have an associated running container:
docker image prune
allows you to clean up dangling images (a dangling image is not tagged and not referenced by any container)
docker image prune -a
will remove all images that are not used by any existing containers
docker image prune -a --filter "until=48h"
you can add a filter (--filter) to limit the images to be pruned, as in this example, only images that are older than 48 hours
You can add the -f or --force flag to prune the images and not prompt for confirmation
You could use this in a scheduled bash script to keep your drive tidy
docker system prune -a helped me.It will remove both unused and dangling images.
You can use docker system prune but it will clear everything in docker.
Its not an image problem its actually cache problem so deleting your images wont work because the problem relies in layer caching.
There is a --no-cache flag in docker build but I don't know if it works with docker pull too.
For someone interested in: (1) using the command line; (2) removing cache only for images that have been removed with docker rmi (i.e., not visible with docker images --all), but for which caches are still present, and for which the Already exists shows for layers when pulling image; you can try this command:
docker builder prune
(It may take up to 15 minutes to run this command, so be patient.)
This command seems to have solved the problem for me. I did not want to use the general, "system-wide" prune / purge / clean docker commands and functionalities, because I had some images and containers running (not related to the image that I have already removed), that I wished to have left as they were.
Source of the solution: https://forums.docker.com/t/how-to-delete-cache/5753/7
I think that the situation of "invisible" cached layers for images removed with docker rmi may happen due to the fact of using docker compose (as suggested also by John Doe in his comment to one of the answers in the current question: docker pull always show "Already exists" for layers during pull even after deleting all images).
So after a lot of searching, I have a solution although I don't think it's necessarily a great one.
The "sledge hammer solution" would be to do:
rm -rf /var/lib/docker
This basically factory resets docker, so you would lose everything. This was fine for my case, but be very careful and think this through before using this one.
Please try this command docker rmi 336d482502ab and then try to pull it again.

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