How can I save the kubernetes pod as a docker image? - docker

I have a pod running Linux, I have let others use it. Now I need to save the changes made by others. Since sometimes I need to delete/restart the pod, the changes are reverted and new pod get created. So I want to save the pod container as docker image and use that image to create a pod.
I have tried kubectl debug node/pool-89899hhdyhd-bygy -it --image=ubuntu then install docker, dockerd inside but they don't have root permission to perform operations, installed crictl they where listing the containers but they don't have options to save them.
Also created a privileged docker image, created a pod from it, then used the command kubectl exec --stdin --tty app-7ff786bc77-d5dhg -- /bin/sh then tried to get running container, but it was not listing the containers. Below is the deployment i used to the privileged docker container
kind: Deployment
apiVersion: apps/v1
metadata:
name: app
labels:
app: backend-app
backend-app: app
spec:
replicas: 1
selector:
matchLabels:
app: backend-app
task: app
template:
metadata:
labels:
app: backend-app
task: app
spec:
nodeSelector:
kubernetes.io/hostname: pool-58i9au7bq-mgs6d
volumes:
- name: task-pv-storage
hostPath:
path: /run/docker.sock
type: Socket
containers:
- name: app
image: registry.digitalocean.com/my_registry/docker_app#sha256:b95016bd9653631277455466b2f60f5dc027f0963633881b5d9b9e2304c57098
ports:
- containerPort: 80
volumeMounts:
- name: task-pv-storage
mountPath: /var/run/docker.sock
Is there any way I can achieve this, get the pod container and save it as a docker image? I am using digitalocean to run my kubernetes apps, I do not ssh access to the node.

This is not a feature of Kubernetes or CRI. Docker does support snapshotting a running container to an image however Kubernetes no longer supports Docker.

Thank you all for your help and suggestions. I found a way to achieve it using the tool nerdctl - https://github.com/containerd/nerdctl.

Related

How to make a deployment file for a kubernetes service that depends on images from Amazon ECR?

A colleague created a K8s cluster for me. I can run services in that cluster without any problem. However, I cannot run services that depend on an image from Amazon ECR, which I really do not understand. Probably, I made a small mistake in my deployment file and thus caused this problem.
Here is my deployment file:
apiVersion: apps/v1
kind: Deployment
metadata:
name: hello-deployment
labels:
app: hello
spec:
replicas: 3
selector:
matchLabels:
app: hello
template:
metadata:
labels:
app: hello
spec:
containers:
- name: hello
image: xxxxxxxxx.yyy.ecr.eu-zzzzz.amazonaws.com/test:latest
ports:
- containerPort: 5000
Here is my service file:
apiVersion: v1
kind: Service
metadata:
name: hello-svc
labels:
app: hello
spec:
type: NodePort
ports:
- port: 5000
nodePort: 30002
protocol: TCP
selector:
app: hello
On the master node, I have run this to ensure kubernetes knows about the deployment and the service.
kubectl create -f dep.yml
kubectl create -f service.yml
I used the K8s extension in vscode to check the logs of my pods.
This is the error I get:
Error from server (BadRequest): container "hello" in pod
"hello-deployment-xxxx-49pbs" is waiting to start: trying and failing
to pull image.
Apparently, pulling is an issue..... This is not happening when using a public image from the public docker hub. Logically, this would be a rights issue. But looks like it is not. I get no error message when running this command on the master node:
docker pull xxxxxxxxx.yyy.ecr.eu-zzzzz.amazonaws.com/test:latest
This command just pulls my image.
I am confused now. I can pull my image with docker pull on the master node . But K8s fails doing the pull. Am I missing something in my deployment file? Some property that says: "repositoryIsPrivateButDoNotComplain"? I just do not get it.
How to fix this so K8s can easily use my image from Amazon ECR?
You should create and use secretes for the ECR authorization.
This is what you need to do.
Create a secrete for the Kubernetes cluster, execute the below-given shell script from a machine from where you can access the AWS account in which ECR registry is hosted. Please change the placeholders as per your setup. Please ensure that the machine on which you execute this shell script should have aws cli installed and aws credential configured. If you are using a windows machine then execute this script in Cygwin or git bash console.
#!/bin/bash
ACCOUNT=<AWS_ACCOUNT_ID>
REGION=<REGION>
SECRET_NAME=<SECRETE_NAME>
EMAIL=<SOME_DUMMY_EMAIL>
TOKEN=`/usr/local/bin/aws ecr --region=$REGION --profile <AWS_PROFILE> get-authorization-token --output text --query authorizationData[].authorizationToken | base64 -d | cut -d: -f2`
kubectl delete secret --ignore-not-found $SECRET_NAME
kubectl create secret docker-registry $SECRET_NAME \
--docker-server=https://${ACCOUNT}.dkr.ecr.${REGION}.amazonaws.com \
--docker-username=AWS \
--docker-password="${TOKEN}" \
--docker-email="${EMAIL}"
Change the deployment and add a section for secrete which you're pods will be using while downloading the image from ECR.
apiVersion: apps/v1
kind: Deployment
metadata:
name: hello-deployment
labels:
app: hello
spec:
replicas: 3
selector:
matchLabels:
app: hello
template:
metadata:
labels:
app: hello
spec:
containers:
- name: hello
image: xxxxxxxxx.yyy.ecr.eu-zzzzz.amazonaws.com/test:latest
ports:
- containerPort: 5000
imagePullSecrets:
- name: SECRET_NAME
Create the pods and service.
IF it succeeds, then still the secret will expire in 12 hours, to overcome that setup a crone ( for recreating the secretes on the Kubernetes cluster periodically. For setting up crone use the same script which is given above.
For the complete picture of how it is happening under the hood please refer to below diagram.
Regards
Amit Meena
For 12 Hour problem, If you are using Kubernetes 1.20, Please configure and use Kubelet image credential provider
https://kubernetes.io/docs/tasks/kubelet-credential-provider/kubelet-credential-provider/
You need to enable alpha feature gate KubeletCredentialProviders in your kubelet
If using Lower Kubernetes Version and this feature is not available then use https://medium.com/#damitj07/how-to-configure-and-use-aws-ecr-with-kubernetes-rancher2-0-6144c626d42c

Hostpath volume not mounting on kubernetes running on Docker-desktop for windows

I am running kubernetes on Docker-desktop for windows. I am connecting to the cluster from my WSL.
all my pods are running correctly. I am trying to mount a volume on my jupyterlab (pod) using hostpath. below is my config
apiVersion: apps/v1
kind: Deployment
metadata:
name: jupyter
labels:
app: jupyter
spec:
replicas: 1
selector:
matchLabels:
app: jupyter
template:
metadata:
labels:
app: jupyter
spec:
containers:
- name: jupyter
image: jupyter:1.1
ports:
- containerPort: 8888
securityContext:
runAsNonRoot: true
runAsUser: 1000
volumeMounts:
- name: mydir
mountPath: /notebooks
volumes:
- name: mydir
hostPath:
# directory location on host
path: /home/<myuser>/data
# this field is optional
type: DirectoryOrCreate
The pod starts without any issues. but i dont see the notbooks which i have kept in my hostpath onto my jupyter labs and vice versa( if i save a notebook in jupyter lab it does not get saved to my hostpath).
i followed the tutorial on https://kubernetes.io/docs/concepts/storage/volumes/#hostpath
i want to point out that i am using the #FROM jupyter/datascience-notebook:python-3.7.6" as my docker image.
i tried mounting /home/jovyan/ but it was giving me access related errors while starting the pod. so i reverted back to "/notebooks"
It looks like an issue with how the path is being written on Windows, I see the issue reported in the references below.
Solution:
If your file is in say C: drive, it should be converted to the below
/host_mnt/c/path/to/my/folder
If the above does not work you may want to remove the "type: DirectoryOrCreate" and retry.
References:
https://github.com/kubernetes/kubernetes/issues/59876#issuecomment-628955935
https://github.com/docker/for-win/issues/1703#issuecomment-366701358 .
If you are using WSL based engine on windows, the path should be /run/desktop/mnt/host/c/<folder>

Permission denied with Docker in Docker in Atlassian Bamboo Server

I'm trying to build a docker image using DIND with Atlassian Bamboo.
I've created the deployment/ StatefulSet as follows:
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
labels:
app: bamboo
name: bamboo
namespace: csf
spec:
replicas: 1
serviceName: bamboo
revisionHistoryLimit: 10
selector:
matchLabels:
app: bamboo
template:
metadata:
creationTimestamp: null
labels:
app: bamboo
spec:
containers:
- image: atlassian/bamboo-server:latest
imagePullPolicy: IfNotPresent
name: bamboo-server
resources: {}
terminationMessagePath: /dev/termination-log
terminationMessagePolicy: File
securityContext:
privileged: true
volumeMounts:
- name: bamboo-home
mountPath: /var/atlassian/application-data/bamboo
- mountPath: /opt/atlassian/bamboo/conf/server.xml
name: bamboo-server-xml
subPath: bamboo-server.xml
- mountPath: /var/run
name: docker-sock
volumes:
- name: bamboo-home
persistentVolumeClaim:
claimName: bamboo-home
- configMap:
defaultMode: 511
name: bamboo-server-xml
name: bamboo-server-xml
- name: docker-sock
hostPath:
path: /var/run
dnsPolicy: ClusterFirst
restartPolicy: Always
schedulerName: default-scheduler
securityContext: {}
terminationGracePeriodSeconds: 30
Note that I've set privileged: true in securityContext to enable this.
However, when trying to run docker images, I get a permission error:
Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Post http://%2Fvar%2Frun%2Fdocker.sock/v1.40/containers/create: dial unix /var/run/docker.sock: connect: permission denied.
See '/var/atlassian/application-data/bamboo/appexecs/docker run --help'
Am I missing something wrt setting up DIND?
The /var/run/docker.sock file on the host system is owned by a different user than the user that is running the bamboo-server container process.
Without knowing any details about your cluster, I would assume docker runs as 'root' (UID=0). The bamboo-server runs as 'bamboo', as can be seen from its Dockerfile, which will normally map to a UID in the 1XXX range on the host system. As these users are different and the container process did not receive any specific permissions over the (host) socket, the error is given.
So I think there are two approaches possible:
Or the container process continues to run as the 'bamboo' user, but is given sufficient permissions on the host system to access /var/run/docker.sock. This would normally mean adding the UID the bamboo user maps to on the host system to the docker group on the host system. However, making changes to the host system might or might not be an option depending on the context of your cluster, and is tricky in a cluster context because the pod could migrate to a different node where the changes were not applied and/or the UID changes.
Or the container is changed as to run as a sufficiently privileged user to begin with, being the root user. There are two ways to accomplish this: 1. you extend and customize the Atlassian provided base image to change the user or 2. you override the user the container runs as at run-time by means of the 'runAsUser' and 'runAsGroup' securityContext instructions as specified here. Both should be '0'.
As mentioned in the documentation here
If you want to run docker as non-root user then you need to add it to the docker group.
Create the docker group if it does not exist
$ sudo groupadd docker
Add your user to the docker group.
$ sudo usermod -aG docker $USER
Log out and log back in so that your group membership is re-evaluated.
$ newgrp docker
Verify that you can run docker commands without sudo
$ docker run hello-world
If that doesn't help you can change the permissions of docker socket to be able to connect to the docker daemon /var/run/docker.sock.
sudo chmod 666 /var/run
A better way to handle this is to run a sidecar container - docker:dind, and export DOCKER_HOST=tcp://dind:2375 in the main Bamboo container. This way you will invoke Docker in a dind container and won't need to mount /var/run/docker.sock

how to restart jenkins service inside pod in kubernetes cluster

I have created a kubernetes cluster and deployed jenkins by following file
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: jenkins-ci
spec:
replicas: 1
template:
metadata:
labels:
run: jenkins-ci
spec:
containers:
- name: jenkins-ci
image: jenkins:2.32.2
ports:
- containerPort: 8080
and service by
apiVersion: v1
kind: Service
metadata:
name: jenkins-cli-lb
spec:
type: NodePort
ports:
# the port that this service should serve on
- port: 8080
nodePort: 30000
# label keys and values that must match in order to receive traffic for this service
selector:
run: jenkins-ci
Now i can access jenkins UI in my browser without any problems. My issue I came into situation in which need to restart jenkins service manually??
Just kubectl delete pods -l run=jenkins-ci - Will delete all pods with this label (your jenkins containers).
Since they are under Deployment, it will re-create the containers. Network routing will be adjusted automatically (again because of the label selector).
See https://kubernetes.io/docs/reference/kubectl/cheatsheet/
You can use command below to enter the pod container.
$ kubectl exec -it kubernetes pod -- /bin/bash
After apply service Jenkins restart command.
For more details please refer :how to restart service inside pod in kubernetes cluster.

Is it correct to attach code through volume in kubernetes?

In order to do ease development in Docker, the code is attached to the containers through volumes. In that way, there is no need to rebuild the images each time the code is changed.
So, is it correct to think to use the same idea in Kubernetes?
PS: I know that the concepts PersistentVolume and PersistentVolumeClaim allow to attach volume, but they are intended for data.
Update
To ease the development, I do need to use the volume for both code and data. This will avoid me to rebuild the images at each change of code.
Below this is what I am trying to do in minikube:
the deployment
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: php-hostpath
spec:
replicas: 1
template:
metadata:
labels:
app: php-hostpath
spec:
containers:
- name: php-hostpath
image: php:7.0-apache
ports:
- containerPort: 80
volumeMounts:
- name: vol-php-hostpath
mountPath: /var/www/html
volumes:
- name: vol-php-hostpath
hostPath:
path: '/home/amine/DockerProjects/gcloud-kubernetes/application/06-hostPath-volume-example-minikube/src/'
the service
apiVersion: v1
kind: Service
metadata:
name: php-hostpath
namespace: default
labels:
app: php-hostpath
spec:
selector:
app: php-hostpath
ports:
- port: 80
targetPort: 80
type: "LoadBalancer"
The service and the deployment are well created in minikube:
$ kubectl get pods -l app=php-hostpath
NAME READY STATUS RESTARTS AGE
php-hostpath-3796606162-bt94w 1/1 Running 0 19m
$ kubectl get service -l app=php-hostpath
NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE
php-hostpath 10.0.0.110 <pending> 80:30135/TCP 27m
The folder src and the file src/index.php are also well created.
<?php
echo "This is my first docker project";
Now I want to check that every thing is running:
$ kubectl exec -ti php-hostpath-3796606162-bt94w bash
root#php-hostpath-3796606162-bt94w:/var/www/html# ls
root#php-hostpath-3796606162-bt94w:/var/www/html# exit
exit
The folder src and the file index.php are not in /var/www/html!
Have I missed something?
PS: if I were in production env, I will not put my code in a volume.
Thanks,
Based on this doc, Host folder sharing is not implemented in the KVM driver yet. This is the driver I am using actually.
To overcome this, there are 2 solutions:
Use the virtualbox driver so that you can mount your hostPath volume by changing the path on you localhost /home/THE_USR/... to /hosthome/THE_USR/...
Mount your volume to the minikube VM based on the command $ minikube mount /home/THE_USR/.... The command will return you the path of your mounted volume on the minikube VM. Example is given down.
Example
(a) mounting a volume on the minikube VM
the minikube mount command returned that path /mount-9p
$ minikube mount -v 3 /home/amine/DockerProjects/gcloud-kubernetes/application/06-hostPath-volume-example-minikube
Mounting /home/amine/DockerProjects/gcloud-kubernetes/application/06-hostPath-volume-example-minikube into /mount-9p on the minikubeVM
This daemon process needs to stay alive for the mount to still be accessible...
2017/03/31 06:42:27 connected
2017/03/31 06:42:27 >>> 192.168.42.241:34012 Tversion tag 65535 msize 8192 version '9P2000.L'
2017/03/31 06:42:27 <<< 192.168.42.241:34012 Rversion tag 65535 msize 8192 version '9P2000'
(b) Specification of the path on the deployment
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: php-hostpath
spec:
replicas: 1
template:
metadata:
labels:
app: php-hostpath
spec:
containers:
- name: php-hostpath
image: php:7.0-apache
ports:
- containerPort: 80
volumeMounts:
- name: vol-php-hostpath
mountPath: /var/www/html
volumes:
- name: vol-php-hostpath
hostPath:
path: /mount-9p
(c) Checking if mounting the volume worked well
amine#amine-Inspiron-N5110:~/DockerProjects/gcloud-kubernetes/application/06-hostPath-volume-example-minikube$ kubectl exec -ti php-hostpath-3498998593-6mxsn bash
root#php-hostpath-3498998593-6mxsn:/var/www/html# cat index.php
<?php
echo "This is my first docker project";
root#php-hostpath-3498998593-6mxsn:/var/www/html# cat index.php
<?php
echo 'This is my first hostPath on kubernetes';
root#php-hostpath-3498998593-6mxsn:/var/www/html# cat index.php
<?php
echo 'This is my first hostPath on kubernetes';
root#php-hostpath-3498998593-6mxsn:/var/www/html#
PS: this kind of volume mounting is only development environment. If I were in production environment, the code will not be mounted: it will be in the image.
PS: I recommend the virtualbox in stead of KVM.
Hope it helps others.
There is hostPath that allows you to bind mount a directory on the node into the a container.
In a multi node cluster you will want to restrict your dev pod to a particular node with nodeSelector (use the built-in label kubernetes.io/hostname: mydevhost).
With minikube look at the Mounted Host Folders section.
In my honest opinion, you can do it, but you shouldn't. One of the features of using containers is that you can have artifacts (containers) with always the same behaviour. A new version of your code should generate a new container. This way you can be sure, when testing, that any new issue detected will be directly related to the new code.
An hybrid approach (that I don't like either but I think is better) is to create a docker that downloads your code (selecting the correct release with envs) and runs it.
Using hostPaths is not a bad idea but can be a mess, if you have a not-so-small cluster.
Of course you can use PV, after all your code is data. You can use a distributed storage filesystem like NFS to do it.

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