I used docker ps/docker ps -a/docker ps -n 1 all not showing my first image.
But it after I using docker pull hello-world it saying it installed successfully
docker pull pulls an image (and all the layers that make it up) to your local machine, but doesn't run anything.
docker ps lists containers on your system.
Once you run that container (using docker run hello-world), you'll see it in dokcer ps.
To view the image you pulled, you could use docker images.
As you find from the previous answer docker pull will download the image (mostly from the docker hub) and when trying to pull next time, it finds the image already in your local machine. To see all the images you have locally, use docker image ls.
Related
I have created a container using the following command: docker container run -i ubuntu. However, when I try to run a command within the container, such as cd, I get the following error: bash: line 1: cd: $'bin\r': No such file or directory. What could be the issue?
When you docker run an image, or use an image in a Dockerfile FROM line, or name an image: in a Docker Compose setup, Docker first checks to see if you have that image locally. If you have that image, Docker just uses it without checking Docker Hub or the other upstream registry.
Meanwhile, you can docker build or docker tag an image with any name you want...even a name that matches an official Docker Hub image.
You mention in a comment that you at some point did run docker build -t ubuntu .... That replaces the ubuntu image with what you built, so when you later docker run ubuntu, it's running your modified image and not the official Docker Hub Ubuntu image.
This is straightforward to fix. If you
docker rmi ubuntu
it will delete your local (modified) copy, and the next time you use it, Docker will automatically pull it from Docker Hub. It should also work to
# Explicitly get the Docker Hub copy of the image
docker pull ubuntu
# Build a custom image, pulling whatever's in the FROM line
docker build --pull -t my/image .
(You can also hit this in a Docker Compose setup if you specify both image: and build:; this instructs Compose on an explicit name to use for the built image. You do not need to repeat the FROM line in image:, and it causes trouble if you do. The resolution is the same as described above. I might leave image: out entirely unless you're planning to push the image to a registry.)
I recently started using podman and realized that images pulled via docker doesn't become available for use to podman and vice-versa. For example:-
If I pull the image using docker CLI, as shown below
docker pull registry.access.redhat.com/ubi7-minimal
and If I want to use the same image with podman or buildah, turns out I cannot
[riprasad#localhost ~]$ podman inspect registry.access.redhat.com/ubi7-minimal
Error: error getting image "registry.access.redhat.com/ubi7-minimal": unable to find 'registry.access.redhat.com/ubi7-minimal' in local storage: no such image
I understand that this is because both podman and docker uses a different storage location and hence the image pulled down via docker doesn't becomes available for use with podman and vice-versa.
[riprasad#localhost ~]$ docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
registry.access.redhat.com/ubi7-minimal latest fc8736ea8c5b 5 weeks ago 81.5MB
[riprasad#localhost ~]$ podman images
REPOSITORY TAG IMAGE ID CREATED SIZE
Is there a way to mitigate this issue, and somehow make docker and podman work inter-changeably on the very same image, irrespective of whether it has been pulled down via docker or podman ??
Docker and Podman do not sure the same storage. They can not, because Docker controls locking to its storage within the daemon. While Podman, Buildah, CRI-O, Skopeo all can share content, because they use the file system.
Podman and the other tools can work with the docker-daemon storage indirectly, via the "docker-daemon" transport.
Something like:
podman run docker-daemon:alpine echo hello
Should work.
Note, that podman is pulling the image out of the docker daemon and is storing the image in containers/storage, and then running the container, it is not using the Docker storage directly.
You can also do
podman push myimage docker-daemon:myimage
To copy an image from containers/storage into the docker daemon.
Adding to #rhatdan's post
podman run docker://alpine echo hello
This worked for me.
For more details: Here->
I have a docker image. I want to analyze the docker image history, for this I can use docker image history command in the docker installed environment.
But when am working in a Openshift cluster, I may not have the access to the docker command here. So here I want get the docker history command result for the given image.
So basically I have a docker image and I don't have docker installed there. In this case how can we get the history of that docker image?
Can anyone please help me on this?
You can get the registry info either via curl or skopeo inspect. But the rest of the metadata is stored inside the image itself so you do have to download at least the final layer.
Docker provides a way to run the container using docker run
Or just pull the container image using docker pull
Found a doc showing mapping between docker commands and kubectl.
Can't find docker pull equivalent in this doc.
If there is no any such equivalent to docker pull, then is there any way to just pull an image using kubectl cli.
In short - no, there is not.
And why would there be? Kubernetes is an orchestration tool for Docker, it will automatically pull pods for you if it needs them, so there's really no need to have a command to pull containers manually.
I think there isn't a kubectl ... equivalent and some of the reasons might be:
they are not equivalent 🙂. When you docker pull an image, you are planning to use it afterwards on your docker host. When you kubectl ... a deployment, you want the platform to schedule everything. For example if you have many worker nodes and the replicas are going to be scheduled to only two of them, then the other nodes don't have to pull the image.
kubectl is a tool that talks to the API server to control the cluster. It would be wrong to make it also responsible for container images (see, Leaky Abstractions) since you have available a lower level tool that talks to the Container Runtime Interface for that: crictl.
k8s-master:~$ crictl --help
NAME:
crictl - client for CRI
USAGE:
crictl [global options] command [command options] [arguments...]
VERSION:
v1.12.0
COMMANDS:
attach Attach to a running container
create Create a new container
exec Run a command in a running container
version Display runtime version information
images List images
inspect Display the status of one or more containers
inspecti Return the status of one or more images
inspectp Display the status of one or more pods
logs Fetch the logs of a container
port-forward Forward local port to a pod
ps List containers
pull Pull an image from a registry
...
pic from: www.aquasec.com/wiki/display/containers/Kubernetes+Architecture+101
what takes place with container run-times under the hood is complicated and keeps evolving. Think about this, people started creating Kubernetes clusters and the container engine used was Docker. Then Docker adopted containerd so we had Kubernetes on top of Docker on top of containerd, which caused problems like this:
Users won't see Kubernetes pulled images with the docker images command... And vice versa, Kubernetes won't see images created by docker pull, docker load or docker build commands...
source / more details: Kubernetes Containerd Integration Goes GA
crictl pull <image name>
There is no need to pull by kubernetes in cli.
Why?
Becuase when you run kubectl create -f template.yml it containe an image and it cjecked that the image is exist or not. If it does not exist it pull image automatically.
You will not find equivalent of docker pull in Kubernetes because this command is related to images management. Explanation below.
One of Docker features is abbility to create Images. You can create your own image using Dockerfile (docker build .) or pull from Docker Hub which contains many pre-built images.
If you use pull command it will just download image, it will not deploy any container.
$ docker pull hello-world
Using default tag: latest
latest: Pulling from library/hello-world
$ docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
hello-world latest fce289e99eb9 5 months ago 1.84kB
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
As you see, $ docker pull will only display download image. As Docker is also responsible for image management you can pull or push images to repository (DockerHub).
To create container in Docker you have to use $ docker run. This command will automatically download image and run container.
$ docker run --name mynginx -p 80:80 -d nginx
Unable to find image 'nginx:latest' locally
latest: Pulling from library/nginx
...
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
4abf804611a8 nginx "nginx -g 'daemon of…" 4 minutes ago Up 4 minutes 0.0.0.0:80->80/tcp mynginx
In short:
Create adds a writeable container on top of your image and sets it up for running whatever command you specified in your CMD. The container ID is reported back but it’s not started.
Start will start any stopped containers. This includes freshly created containers.
Run is a combination of create and start. It creates the container and starts it.
Kubernetes is container-orchestration system so it is not responsible for creating or edit images. That is why you will not find equivalent of docker pull (download only image).
Commands like kubectl apply -f <deployment> with image inside YAML file or kubectl run nginx --image=nginx are based on images from DockerHub (more like docker create).
Hope it helped.
It could be a bit tricky, but it is possible to achieve similar to docker pull results using kubectl. You just need to know how to exit the containers with zero exit code.
The idea is to pull several images on all nodes in the Kubernetes cluster.
For doing this you could create a DaemonSet which will try to create Pods on every applicable node in the cluster. To pull several images at once, just add several initContainers to the DaemonSet template. ImagePullPolicy set to IfNotPresent, restartPolicy set to Never. Set command individually to each initContainer to make it exit successfully. You need something like sh -c "exit 0", just ensure that container has sh binary inside, or use another possible command that usually gives you zero exit code: <appname_binary> version or <appname_binary> --help.
After applying that DaemonSet to the cluster, Kubernetes creates Pods from DaemonSet templates on each node and runs each initContainer in the Pod in order of presence. Before starting each container kubelet pulls the image required to run that container.
When you see that all DaemonSet Pods completed successfuly - you can be sure that on every node you have all images, required for running those containers.
You can play with nodeAffinity or taints/tolerations if you want to run the DaemonSet only on specific nodes.
I built a docker image like this:
sudo docker image build -t docker_image_gotk3 .
If I execute
sudo docker images I can see the line:
REPOSITORY TAG IMAGE ID CREATED SIZE
docker_image_gotk3 latest c13f7fcdb11d 14 minutes ago 20.4MB
I searched the complete file system and I didn't find a single file named docker_image_gotk3. How do I actually get it?
You have to export the docker image to push GitHub.
docker save -o docker_image_gotk3.tar docker_image_gotk3
ls -sh docker_image_gotk3.tar
20.4M docker_image_gotk3.tar
Github doesn't appear to have a Docker registry service as of now.
Maybe you could try tracking your image in Docker Hub as an alternative to what Tibi02 proposes?
Just create an account at https://hub.docker.com/ if you don't have one already, and do the following:
docker login in your terminal to authenticate in Docker Hub
docker image push your_username/docker_image_gotk3:latest to upload your image to the registry
Then you should be able to see it at https://cloud.docker.com/repository/docker/you_username/docker_image_gotk3, and download your image with docker image pull your_username/docker_image_gotk3:latest
Hope this helps!