Pull an Image from a Private Registry

This page shows how to create a Pod that uses a Secret to pull an image from a private Docker registry or repository.

Before you begin

You need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. If you do not already have a cluster, you can create one by using Minikube, or you can use one of these Kubernetes playgrounds:
Katacoda
Play with Kubernetes

To check the version, enter kubectl version.

To do this exercise, you need a Docker ID and password.

Log in to Docker

On your laptop, you must authenticate with a registry in order to pull a private image:

docker login

When prompted, enter your Docker username and password.

The login process creates or updates a config.json file that holds an authorization token.

View the config.json file:

cat ~/.docker/config.json

The output contains a section similar to this:

 
   {
    "auths": {
        "https://index.docker.io/v1/": {
            "auth": "c3R...zE2"
        }
    }
}
 
  

Note: If you use a Docker credentials store, you won’t see that auth entry but a credsStore entry with the name of the store as value.

Create a Secret in the cluster that holds your authorization token

A Kubernetes cluster uses the Secret of docker-registry type to authenticate with a container registry to pull a private image.

Create this Secret, naming it regcred:

 
   kubectl create secret docker-registry regcred --docker-server=<your-registry-server> --docker-username=<your-name> --docker-password=<your-pword> --docker-email=<your-email>

where:

<your-registry-server> is your Private Docker Registry FQDN. (https://index.docker.io/v1/ for DockerHub)
<your-name> is your Docker username.
<your-pword> is your Docker password.
<your-email> is your Docker email.

You have successfully set your Docker credentials in the cluster as a Secret called regcred.

Inspecting the Secret `regcred`

To understand the contents of the regcred Secret you just created, start by viewing the Secret in YAML format:

kubectl get secret regcred --output=yaml

The output is similar to this:

 
   apiVersion: v1
data:
  .dockerconfigjson: eyJodHRwczovL2luZGV4L ... J0QUl6RTIifX0=
kind: Secret
metadata:
  ...
  name: regcred
  ...
type: kubernetes.io/dockerconfigjson
 
  

The value of the .dockerconfigjson field is a base64 representation of your Docker credentials.

To understand what is in the .dockerconfigjson field, convert the secret data to a readable format:

 
   kubectl get secret regcred --output="jsonpath={.data.\.dockerconfigjson}" | base64 -d

The output is similar to this:

{"auths":{"yourprivateregistry.com":{"username":"janedoe","password":"xxxxxxxxxxx","email":"[email protected]","auth":"c3R...zE2"}}}

To understand what is in the auth field, convert the base64-encoded data to a readable format:

echo "c3R...zE2" | base64 -d

The output, username and password concatenated with a :, is similar to this:

janedoe:xxxxxxxxxxx

Notice that the Secret data contains the authorization token similar to your local ~/.docker/config.json file.

You have successfully set your Docker credentials as a Secret called regcred in the cluster.

Create a Pod that uses your Secret

Here is a configuration file for a Pod that needs access to your Docker credentials in regcred:

`private-reg-pod.yaml`
`apiVersion: v1 kind: Pod metadata: name: private-reg spec: containers: - name: private-reg-container image: <your-private-image> imagePullSecrets: - name: regcred`

Download the above file:

 
   wget -O my-private-reg-pod.yaml https://k8s.io/docs/tasks/configure-pod-container/private-reg-pod.yaml

In file my-private-reg-pod.yaml, replace <your-private-image> with the path to an image in a private registry such as:

janedoe/jdoe-private:v1

To pull the image from the private registry, Kubernetes needs credentials. The imagePullSecrets field in the configuration file specifies that Kubernetes should get the credentials from a Secret named regcred.

Create a Pod that uses your Secret, and verify that the Pod is running:

 
   kubectl create -f my-private-reg-pod.yaml
kubectl get pod private-reg

What’s next

Learn more about Secrets.
Learn more about using a private registry.
See kubectl create secret docker-registry.
See Secret.
See the imagePullSecrets field of PodSpec.