I specified a docker image when creating a small VM. Because of this feature, I expected a fairly hands-off way of updating the container to the latest image, but I can't find any documentation on how to do that, or at least a method that works. What the documentation says is that updating the configuration will cause the container to be updated to the latest image and the VM will be stopped & restarted, but this doesn't happen.
I've only been able to update the container by using the Cloud shell from the container registry page. Am I missing a more obvious way to do this?
Docker Tags
The version of the image is specified in the tag.
If you want the most recent, use the latest tag.
Otherwise, a version can be specified.
Example:
fedora/httpd:version1.0 will grab fedora image with version1.0.
fedora/httpd:latest will grab the latest fedora image.
Check what versioning format your image is using, and specify a version when pulling the image.
Updating your container to use newest image
To do this, you likely need to just stop the container, specify the image you want to use, and run the new container.
The key here is to trigger a new pull from the registry. If you are using the latest tag, the latest image should be pulled from the registry. Your important data/configuration should all be made persistent through volume mounting, etc. So you should just be able to plug-and-play with this new image.
If you are looking for the simplest way, maybe try writing a script to stop your running container, pull the latest image, and run this image.
It is slightly challenging to give an exact answer on this issue because there a couple ways to go about it.
Documentation for Docker Pull and Docker Tag
Use Tag for image instead of latest.
use something like this
Image: name_of_imgae:1.0
Related
I'm using some docker images, which I have pulled from a registry:
docker pull registry.example.com/project/backend:latest
docker pull registry.example.com/project/frontend:latest
Now there is a new version on the server registry. If I do a new pull, I will overwrite the current images. But I need to keep the current working images in case I do get some problems with the newest latest images.
So, how do I create a kind of backup of my running backend:latest and frontend:latest? After that I can pull the latest latest image and in case I need to, I can use the old working images...
To keep the current image on your local environment you can use docker tag
docker tag SOURCE_IMAGE[:TAG] TARGET_IMAGE[:TAG]
For example:
docker tag registry.example.com/project/backend:latest registry.example.com/project/backend:backup
Then when you pull the latest, the registry.example.com/project/backend:backup still existing
Pulling an image never deletes an existing image. However, if you have an image with the same name, the old image will become unnamed, and you'll have to refer to it by its image ID.
You've now seen the downside to using :latest tags. This is why it is better to reference an image by a specific version tag that the maintainer won't re-push.
First, you shouldn't be using latest in production environments. Rather define a tag you confirmed working.
And instead of executing stuff in an image to set it up, you should write a Dockerfile and make the installation repeatable and create your local image. That's actually one of the main reasons why docker is used.
What command(s) do I have to run to retrieve an older image of a software offered in Docker?
I have problems with the latest image of localstack so I though I could try older versions to see what happens. However, I saw a comment in an issue mentioning editing the YAML file this way:
image: localstack/localstack:0.9
but no other info... (it was not the point of the issue, so it's understandable).
I've been looking around and saw many posts about getting the latest image (i.e. docker update ...), but nothing that would allow me to go back in time except for images that I would happen to already have.
Just the change above had absolutely no effect. I'm wondering how can I get Docker to download an older image so I can run that older one instead of the latest? I'm also wondering about how to find a list of available tags for a given docker to make sure I use a version that actually exists.
You should look for existing tags at desired repo's hub.
If you are using docker-compose the correct way to do it is:
image: <image>:<tag>
If no tag was found then it is not available or does not exist.
Here are tags available at localstack hub
Is it possible with Docker to get a previous version of Docker image(not the current one), for example:
FROM base:previous
or something like this. Unfortunately, I don't know this image digest.
In your example previous is the tag of the image. If you know the tag of the older image just write that.
As an example the official mysql image (https://hub.docker.com/_/mysql/) lists several tags ranging from 5.5 to 8.0
So I can start an instance of mysql 5.5 using
docker run mysql:5.5
You could also do that in your Dockerfile, if the older version is 1.0 you would do:
FROM base:1.0
If you don't know which tag you used previously you might be able to find it if you list all your images locally
docker images
Good luck!
I want to upgrade the image where an existing container runs. After executing docker pull, I got the latest image. But the container still run on the older image. Is it possible to make an existing container to run on latest image? Thanks.
It's not possible at this time, but there's an open feature request to support this use case.
I was using centos image from https://registry.hub.docker.com/u/blalor/centos/
For some reason Blalor decided to remove passwd from the list of packages installed on the base image and my dockers stopped working on new deployments. Why does not docker know the build which was used for my dockers? I have had to change my base images now and change every server's docker image.
I could not use the tag feature because there is the tagging for the blalor's images? Do I have to use the source code and host the centos image myself so that it does not change again?
You do not need to use sources. If you have a working image, you can do docker history <your image> to see the image ID that was used and tag the proper one into shortfellow/centos. If you do not have a working image, on the link you provided, there is a build detail section with the history of build. You can see that on January 13th, 2014, it has been built and the image then was a531daec9f98. You can do FROM a531daec9f98 on your dockerfile to make sure it will never change or you can docker tag a531daec9f98 shortfellow/centos (you will need to docker pull a531daec9f98 before).
It is very similar to git in a sense that if you are using someone's repository, and if that someone does not use tags or branches, when he updates his reposiroty and you re pull, you will have the latest version with the new changes. In order to get back to the version you liked, you need to find the commit id. The solution would be to fork the repository. Which you can do on Docker by tagging the image under you username and pushing to a registry (docker push username/image)