How to Setup Private Docker Registry in Kubernetes (k8s)

It is always recommended to have private docker registry or repository in your Kubernetes cluster. Docker private registry allows the developers to push and pull their private container images. Once the application’s containers are pushed to private registry then developers can use the path of their private registry while creating and deploying their yaml files.

In this article, we will learn how we can deploy private docker registry as a deployment on top of Kubernetes cluster. I am assuming Kubernetes cluster is already up and running.

Kubernetes lab details for setting up private docker registry

  • k8s-master – – CentOS 7
  • k8s-worker-1 – – CentOS 7
  • k8s-worker-2 –  – CentOS 7
  • kadmin user with sudo rights
  • NFS share ‘/opt/certs’ & ‘/opt/registry’

Note:  In my case, I have setup nfs server on master node and exported /opt/certs and /opt/registry as nfs share.

Before starting the deployment of private registry, please make sure these nfs shares are mounted on each worker nodes. Run the following commands on each worker node.

$ sudo mkdir /opt/certs /opt/registry $ sudo mount /opt/certs $ sudo mount /opt/registry

For permanent mount, add nfs entries in /etc/fstab file.

In place of mounting these nfs shares, we can also create nfs based persistent volumes and later we can use these persistent volumes in yaml file.

Let’s dive into installation and configuration steps of private docker registry in Kubernetes.

Step 1) Generate self-signed certificates for private registry

Login to your control plane or master node and use openssl command to generate self-signed certificates for private docker repository.

[[email protected] ~]$ cd /opt [[email protected] opt]$ sudo openssl req -newkey rsa:4096 -nodes -sha256 -keyout ./certs/registry.key -x509 -days 365 -out ./certs/registry.crt


Once the key and certificate file are generated, use ls command to verify them,

[[email protected] opt]$ ls -l certs/ total 8 -rw-r--r--. 1 root root 2114 Sep 26 03:26 registry.crt -rw-r--r--. 1 root root 3272 Sep 26 03:26 registry.key [[email protected] opt]$

Step 2) Deploy private registry as deployment via yaml file

On your master node, create a private-registry.yaml file with the following contents

[[email protected] ~]$ mkdir docker-repo [[email protected] ~]$ cd docker-repo/ [[email protected] docker-repo]$ vi private-registry.yaml apiVersion: apps/v1 kind: Deployment metadata:   name: private-repository-k8s   labels:     app: private-repository-k8s spec:   replicas: 1   selector:     matchLabels:       app: private-repository-k8s   template:     metadata:       labels:         app: private-repository-k8s     spec:       volumes:       - name: certs-vol         hostPath:           path: /opt/certs           type: Directory       - name: registry-vol         hostPath:           path: /opt/registry           type: Directory       containers:         - image: registry:2           name: private-repository-k8s           imagePullPolicy: IfNotPresent           env:           - name: REGISTRY_HTTP_TLS_CERTIFICATE             value: "/certs/registry.crt"           - name: REGISTRY_HTTP_TLS_KEY             value: "/certs/registry.key"           ports:             - containerPort: 5000           volumeMounts:           - name: certs-vol             mountPath: /certs           - name: registry-vol             mountPath: /var/lib/registry

save and close the yaml file


Run the following kubectl command deploy the private registry using above created yaml file,

[[email protected] docker-repo]$ kubectl create -f private-registry.yaml deployment.apps/private-repository-k8s created [[email protected] docker-repo]$

Execute below kubectl commands to verify status of registry deployment and its pod.

[[email protected] ~]$ kubectl get deployments private-repository-k8s NAME                     READY   UP-TO-DATE   AVAILABLE   AGE private-repository-k8s   1/1     1            1           3m32s [[email protected] ~]$ [[email protected] ~]$ kubectl get pods | grep -i private-repo private-repository-k8s-85cf76b9d7-qsjxq   1/1     Running   0          5m14s [[email protected] ~]$

Perfect, above output confirms that registry has been deployed successfully, Now copy the registry certificate file to worker nodes and master node under the folder “/etc/pki/ca-trust/source/anchors“. Execute the following commands on master node and each worker nodes

$ sudo cp /opt/certs/registry.crt /etc/pki/ca-trust/source/anchors/ $ sudo update-ca-trust $ sudo systemctl restart docker

Step 3) Expose registry deployment as a nodeport service type

To expose registry deployment as a nodeport service type, create the following yaml file with the beneath contents,

[[email protected] ~]$ cd docker-repo/ [[email protected] docker-repo]$ vi private-registry-svc.yaml apiVersion: v1 kind: Service metadata:   labels:     app: private-repository-k8s   name: private-repository-k8s spec:   ports:   - port: 5000     nodePort: 31320     protocol: TCP     targetPort: 5000   selector:     app: private-repository-k8s   type: NodePort

save and close the file.

Now deploy the service by running following kubectl command,

[[email protected] docker-repo]$ kubectl create -f private-registry-svc.yaml service/private-repository-k8s created [[email protected] docker-repo]$

Run below kubectl command to verify the service status,

[[email protected] ~]$ kubectl get svc private-repository-k8s NAME                     TYPE       CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE private-repository-k8s   NodePort   <none>        5000:31320/TCP   2m1s [[email protected] ~]$

Step 4) Test and Use private docker registry in k8s

To test private registry, we will download nginx image locally and then will upload that image to private registry, from the master node run the following set of commands,

[[email protected] ~]$ sudo docker pull nginx [[email protected] ~]$ sudo docker tag nginx:latest k8s-master:31320/nginx:1.17 [[email protected] ~]$ sudo docker push k8s-master:31320/nginx:1.17

Output of above command would like below:


Run below docker command to verify whether nginx is uploaded to private repository or not.

[[email protected] ~]$ sudo docker image ls | grep -i nginx nginx                                latest              7e4d58f0e5f3        2 weeks ago         133MB k8s-master:31320/nginx               1.17                7e4d58f0e5f3        2 weeks ago         133MB [[email protected] ~]$

Now, let’s deploy a nginx based deployment and in the yaml file specify the image’s path as our private docker registry. Example is shown below:

[[email protected] ~]$ vi nginx-test-deployment.yaml apiVersion: apps/v1 kind: Deployment metadata:   name: nginx-test-deployment   labels:     app: nginx spec:   replicas: 3   selector:     matchLabels:       app: nginx   template:     metadata:       labels:         app: nginx     spec:       containers:       - name: nginx-1-17         image: k8s-master:31320/nginx:1.17         ports:         - containerPort: 80

Save and Close the file


Run following kubectl commands,

[[email protected] ~]$ kubectl create -f nginx-test-deployment.yaml deployment.apps/nginx-test-deployment created [[email protected] ~]$ kubectl get deployments  nginx-test-deployment NAME                    READY   UP-TO-DATE   AVAILABLE   AGE nginx-test-deployment   3/3     3            3           13s [[email protected] ~]$ [[email protected] ~]$ kubectl get  pods | grep nginx-test-deployment nginx-test-deployment-f488694b5-2rvmv     1/1     Running   0          80s nginx-test-deployment-f488694b5-8kb6c     1/1     Running   0          80s nginx-test-deployment-f488694b5-dgcxl     1/1     Running   0          80s [[email protected] ~]$

Try to describe any pod using ‘kubectl describe‘ command and verify image path

[[email protected] ~]$ kubectl describe pod nginx-test-deployment-f488694b5-2rvmv

Output of above command would be,


Above output confirms that container’s image path is our private docker registry, so it means nginx image has been downloaded from private registry. That’s all from this article, I hope these steps help you to setup private docker registry on your Kubernetes cluster. Please do share your feedback and comments in the comments section below.

Also ReadHow to Setup Kubernetes Cluster on Google Cloud Platform (GCP)

Also ReadHow to Setup NGINX Ingress Controller in Kubernetes

The post How to Setup Private Docker Registry in Kubernetes (k8s) first appeared on Linuxtechi.

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