If your container uses an image thats held in a private repository then you will need to authenticate before accessing it.

This post will cover the different ways possible to authenticate with a docker registry.

Creating the Registry secret

The first step is to create the secret. In this example I will use azure container registry.

kubectl create secret docker-registry azure \
  --docker-server myregistry.azurecr.io \      
  --docker-username <registryusername> \
  --docker-password <registrypassword>

Using Deployment YAML

You can update your deployment YAML to utilise the above secret.

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: test
  name: test
  namespace: test
spec:
  selector:
    matchLabels:
      app: test
  template:
    metadata:
      labels:
        app: test
    spec:
      containers:
          image: myregistry.azurecr.io/test-app
          imagePullPolicy: Always
          name: test
      imagePullSecrets:
        - name: azure

Using a Service Account

Each namespace in Kubernetes is created with a default service account. This service account can be use a docker-registry secret. The benefit of adding a service account this way is that you will not need to update the existing YAML. Any containers in this namespace will use the ImagePull secret by default.

kubectl edit serviceaccount default -n test

Update the YAML to add the imagePullSecret like below.

apiVersion: v1
kind: ServiceAccount
metadata:
  name: default
  namespace: test
secrets:
- name: default-token-2v4n2
imagePullSecrets:
- name: azure