This page shows how to create a Pod that uses a Secret to pull an image from a private container image registry or repository.
You need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. It is recommended to run this tutorial on a cluster with at least two nodes that are not acting as control plane hosts. If you do not already have a cluster, you can create one by using minikube or you can use one of these Kubernetes playgrounds:
To do this exercise, you need the docker command line tool, and a Docker ID for which you know the password.
On your laptop, you must authenticate with a registry in order to pull a private image.
Use the docker tool to log in to Docker Hub. See the log in section of Docker ID accounts for more information.
docker login
When prompted, enter your Docker ID, and then the credential you want to use (access token, or the password for your Docker ID).
The login process creates or updates a config.json file that holds an authorization token. Review how Kubernetes interprets this file.
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"
}
}
}
auth entry but a credsStore entry with the name of the store as value. A Kubernetes cluster uses the Secret of kubernetes.io/dockerconfigjson type to authenticate with a container registry to pull a private image.
If you already ran docker login, you can copy that credential into Kubernetes:
kubectl create secret generic regcred \
--from-file=.dockerconfigjson=<path/to/.docker/config.json> \
--type=kubernetes.io/dockerconfigjson
If you need more control (for example, to set a namespace or a label on the new secret) then you can customise the Secret before storing it. Be sure to:
.dockerconfigjson
data[".dockerconfigjson"]
type to kubernetes.io/dockerconfigjson
Example:
apiVersion: v1
kind: Secret
metadata:
name: myregistrykey
namespace: awesomeapps
data:
.dockerconfigjson: UmVhbGx5IHJlYWxseSByZWVlZWVlZWVlZWFhYWFhYWFhYWFhYWFhYWFhYWFhYWFhYWFhYWxsbGxsbGxsbGxsbGxsbGxsbGxsbGxsbGxsbGxsbGx5eXl5eXl5eXl5eXl5eXl5eXl5eSBsbGxsbGxsbGxsbGxsbG9vb29vb29vb29vb29vb29vb29vb29vb29vb25ubm5ubm5ubm5ubm5ubm5ubm5ubm5ubmdnZ2dnZ2dnZ2dnZ2dnZ2dnZ2cgYXV0aCBrZXlzCg==
type: kubernetes.io/dockerconfigjson
If you get the error message error: no objects passed to create, it may mean the base64 encoded string is invalid. If you get an error message like Secret "myregistrykey" is invalid: data[.dockerconfigjson]: invalid value ..., it means the base64 encoded string in the data was successfully decoded, but could not be parsed as a .docker/config.json file.
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. Use 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.
kubectl is running. regcred
To understand the contents of the regcred Secret you created, start by viewing the Secret in YAML format:
kubectl get secret regcred --output=yaml
The output is similar to this:
apiVersion: v1
kind: Secret
metadata:
...
name: regcred
...
data:
.dockerconfigjson: eyJodHRwczovL2luZGV4L ... J0QUl6RTIifX0=
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 --decode
The output is similar to this:
{"auths":{"your.private.registry.example.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 --decode
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.
Here is a manifest for an example Pod that needs access to your Docker credentials in regcred:
pods/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 onto your computer:
curl -L -O my-private-reg-pod.yaml https://k8s.io/examples/pods/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:
your.private.registry.example.com/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 apply -f my-private-reg-pod.yaml
kubectl get pod private-reg
imagePullSecrets field within the container definitions of a Pod
© 2022 The Kubernetes Authors
Documentation Distributed under CC BY 4.0.
https://kubernetes.io/docs/tasks/configure-pod-container/pull-image-private-registry/