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. 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 check the version, enterkubectl 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"
}
}
}
auth
entry but a credsStore
entry with the name of the store as value.
Create a Secret based on existing Docker credentials
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:
- set the name of the data item to
.dockerconfigjson
- base64 encode the docker file and paste that string, unbroken
as the value for field
data[".dockerconfigjson"]
- set
type
tokubernetes.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 a Secret by providing credentials on the command line
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. Usehttps://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.
Inspecting the Secret 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":"jdoe@example.com","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.
Create a Pod that uses your Secret
Here is a configuration file for a Pod that needs access to your Docker credentials in regcred
:
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/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
What's next
- Learn more about Secrets.
- Learn more about using a private registry.
- Learn more about adding image pull secrets to a service account.
- See kubectl create secret docker-registry.
- See Secret.
- See the
imagePullSecrets
field of PodSpec.