In my use case I always fetch the image tagged with "latest" tag. This "latest" tag gets updated regularly. So even if the latest tag image is updated on registry, the "docker run" command does not update it on local host. This is expected behavior as the "latest" image exists on local host.
But I want to make sure that if the "latest" image on local host and registry are different then it should pull the latest image from registry.
Is there any way to achieve this?
You can manually docker pull the image before you run it. This is fairly inexpensive, especially if the image hasn't changed. You can do it while the old container is still running to minimize downtime.
docker pull the-image
docker stop the-container
docker rm the-container
docker run -d ... --name the-container the-image
In an automated environment you might consider avoiding the latest tag and other similar fixed strings due to exactly this ambiguity. In Kubernetes, for example, the default behavior is to reuse a local image that has some name, which can result in different nodes running different latest images. If you label your images with a date stamp or source-control ID or something else such that every image has a unique tag, you can just use that tag.
Finding the tag value can be problematic outside the context of a continuous-deployment system; Docker doesn't have any built-in way to find the most recent tag for an image.
# docker pull the-image:20220704 # optional
docker stop the-container
docker rm the-container
docker run -d ... --name the-container the-image:20220704
docker rmi the-image:20220630
One notable advantage of this last approach is that it's very easy to go back to an earlier build if today's build happens to be broken; just switch the image tag back a build or two.
Related
Here is the link of docker hub from where I am pulling the image "https://hub.docker.com/r/zcgzcgzcg/squadv2/tags"
My main motive is to run the environment on my machine locally.
If you do not specify which version of zcgzcgzcg/squadv2 you want, Docker will, per default use the tag latest.
But you don't have any image zcgzcgzcg/squadv2:latest.
You have one tagged 4.0, though, so:
docker run zcgzcgzcg/squadv2:4.0
Is what you are looking for.
This is implicitly described in the documentation where they point at the fact that:
$ docker run --name test -it debian
This example runs a container named test using the debian:latest image.
Source: https://docs.docker.com/engine/reference/commandline/run/#assign-name-and-allocate-pseudo-tty---name--it
But it is also explicitly descriped in the docker pull page:
If no tag is provided, Docker Engine uses the :latest tag as a default.
Source: https://docs.docker.com/engine/reference/commandline/pull/#pull-an-image-from-docker-hub
The problem is you are not specifying the tag in your docker run command. You have pulled 4.0, as you can see in the docker images output - but when you don't specify the tag, it will default to latest - which you don't have. So, try this:
docker run zcgzcgzcg/squadv2:4.0
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)
What happens on docker registry server space side when an image is created from same docker file. So, for example in case below, if I push an image with tag 1.0 and then create another image with same docker file and push that with tag 1.1. Is it going to take any additional space on docker registry?
docker build . -t myRegistry.com/myImage:1.0
docker push myRegistry.com/myImage:1.0
docker build . -t myRegistry.com/myImage:1.1
docker push myRegistry.com/myImage:1.1
docker build . -t myRegistry.com/myImage:1.2
docker push myRegistry.com/myImage:1.2
docker build . -t myRegistry.com/myImage:1.3
docker push myRegistry.com/myImage:1.3
In your sample case, the container registry will use the same image, which is calculated by the image's sha256 value (also known as the IMAGE ID) -- the tag is simply alias to that unique image.
It's a one-to-many relationship, i.e., you can have many tags point to the same image. You can use docker images --no-trunc to see the full value of the IMAGE ID. (Note this is useful if you have consistency issues using common tags like "latest" or "develop" since you can't be sure which image it actually is unless you use the sha256 value.)
For builds on different machines/environments, using the same Dockerfile with the same files may result in the same hash, but it depends on many variables like how dynamic your dependencies are, if timestamps have changed, etc.
As #Henry mentioned, this further applies (largely behind the scenes) to individual layers of an image:
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.
see docs
Btw, to see a container's sha256 value to see which image it came from, you can inspect it, e.g., docker inspect --format='{{index .RepoDigests 0}}' mongo:3.4-jessie
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.
I created a new image running:
docker build -t team1/es-image2 . | tee build.log
First, the create date doesn't reflect today's date. I wasn't concerned with that at first but after running it, it sort of makes sense...the running image is from another image created previously. I ran it with this command:
docker run -i -t --rm -P team1/es-image2
I verified that the correct image was running using:
docker ps
I deleted the older image and tried running again but it still appears to be running the older image because -P showed all the older mapped ports and the working directory was also from the older image.
So, I can't understand why, the build is using the older containers even though the Dockerfile is not specifying all the items that were specified in the older image.
Thanks!
docker ps
is only to show container.
To show images you need to use
docker images
And to delete them use
docker rmi
A little clarification about image and container.
An image is the definition of a container, and a container is a part of the system isolated from the current directory tree.
You use an image to run a container. You can use the same image to run multiple container.
When building the image from the Dockerfile, you may specify --no-cache=true to exclude any intermediate builds.