How to use Azure Container Registry in Kubernetes

Written by Mehrdad Zandi

What is Azure Container Registry (ACR)

 

 

Azure Container Registry (ACR) is a private registry service for building, storing, and managing container images and related artifacts like as Dockerhub. ACR is used specially by Enterprises which don’t want to have their containers on a public share.

ACR comes in three pricing tiers: Basic, Standard, and Premium. The main difference between them is the amount of included storage and the number of webhooks you can use. Additionally, the premium tier supports geo-replication. This means that your images are still available when a data center goes down.

In this post, I will describe  how to create ACR,  how to upload images to ACR, and how to pull images from ACR by configuring your Microservice and  Azure Kubernetes cluster  to run them in your  Kubernetes cluster.

Prerequisites

 

Create Azure Container Registry in the Azure Portal

I have described in my post Azure Container Registry (ACR) , how to create and how to push image to ACR. You  can create ACR by looking to this post.

Here I have  created ACR with name: mehzanContainerRegistry with Resource Group: mehzanRSG, in Region: Sweden Central.

Pushing Image to ACR

You have two alternative to push image to ACR:

  • Alternative 1: importing the image from Dockerhub.
  • Alternative 2: uploading it from a CI/CD pipeline.

I am going to describe the both alternatives in this post

Alternative 1: Import Image from Dockerhub into ACR

To import the image, use the following Azure CLI commands: (run az login first and then az acr import ..)

az login
az acr import --name mehzancontainerregistry --source docker.io/mehzan07/productmicroservice:latest  --image productmicroservice:latest

 

The first line logs you into your Azure subscription and the second one takes the name of your ACR (name should be lowercase), the source image from Dockerhub, and the image name which will be created in ACR .

In here I have taken the  productmicroservice  image from my Dockerhub:  docker.io/mehzan07. (Your image should be exist in the your Dockerhub, otherwise you can push it from your local).

If importing is succeeded then navigate to your  ARC registry in the  Azure portal and select Repositories, then you can see productmicroservice (as shown in the following figure)If you double click it shows tag: latest.

 

azure container Importing Image: product microservice from Dockerhub to ACR

 Create Azure Kubernetes Service (AKS)

You have to  create an Azure Kubernetes Service (AKS), To Create AKS look to my post: Azure Kubernetes Service (AKS)

I have created AKS with name: microservice-aks with Resource group: mehzanRSG in Region: Sweden Central ( in the same Resource group and and same Region for ACR which I have created in this post).

Note: I haven’t create any Services and Progress yet, I shall create this later on.

Pulling Image from Azure Container Register to Kubernetes (aks)

To pull this image from kubernetes we should authorize Kubernetes to pull images from ACR.

Kubernetes is not authorized to pull the image. This is because ACR is a private container registry and you have to give Kubernetes permission to pull the images.

Allowing Kubernetes to pull ACR Images

To allow Kubernetes to pull images from ACR, you first have to create a service principal and give it the acrpull role.

Service principals define who can access the application, and what resources the application can access. A service principal is created in each tenant where the application is used, and references the globally unique application object. The tenant secures the service principal sign-in and access to resources. For more about  Service Principal.

Use the following bash script to create the service principal and assign it the acrpull role.

1- Run the following script on Azure CLi command (start from portal):

 

ACR_NAME=mehzancontainerregistry
SERVICE_PRINCIPAL_NAME=acr-service-principal

ACR_REGISTRY_ID=$(az acr show --name $ACR_NAME --query id --output tsv)

PASSWORD=$(az ad sp create-for-rbac --name $SERVICE_PRINCIPAL_NAME --scopes $ACR_REGISTRY_ID --role acrpull --query "password" --output tsv)
USER_NAME=$(az ad sp list --display-name $SERVICE_PRINCIPAL_NAME --query "[].appId" --output tsv)

echo "Service principal ID: $USER_NAME"
echo "Service principal password: $PASSWORD"

Where the mehzancontainerregisry is the ACR name which we have created in the beginning of this post.

Note: If running of copy of this script is not worked  then you should first copy and paste it to notepad and then take from there to run in the Azure CLI.

If it is succeed then output will be like as following:

Service principal ID: f8922aa7-81df-48a5-a8c6-5b158edb6072
Service principal password: oDm8Q~eVBH-15mE25t3EIqyTt0pc87UWmhVURaIM

Save these Service principal ID and  Service principal password: and use them in the next step (in the following).

2- Next, create an image pull secret with the following command  in the command line:

 

kubectl create secret docker-registry acr-secret  --namespace default --docker-server=mehzancontainerregistry.azurecr.io --docker-username=f8922aa7-81df-48a5-a8c6-5b158edb6072  --docker-password=oDm8Q~eVBH-15mE25t3EIqyTt0pc87UWmhVURaIM

where  docker- server value (mehzancontainerregistry.azurecr.io) is ACR Service and it is created with creating of ACR in the beginning. namespace: as default,  docker-username: the Service principal ID  value  and docker password f Service principal password value from the step 1.

If it succeed the output will be: “secret/acr-secret created “

namespace value can be found from Ks8: dashboard as shown in  the following figure:

 

azure-container-registry-in-kubernetes-11.png
Namespace: default on ks8: dashboard on top-right dropdown.

3- Use the Image Pull Secret in  your Microservice (productmicroservice)
After the image pull secret was created, you have to tell your microservice to use it.  I  have used the values.yaml  file (under charts:productmicroservice) for values, as  following code:

 

imagePullSecrets:
  - name: acr-secret

I have build image and pushed to  my dockerhub before importing of image. The Source code can be found in my Github.

If you used a different name for your secret in the kubectl create secret docker-registry, then you have to use your name instead of acr-secret.

4- Copy the following yaml  in somewhere in your local machine and give a file name (like as : acr-secret.yml)

 

apiVersion: apps/v1
kind: Deployment
metadata:
  name: productmicroservice 
  namespace: default
spec:
  replicas: 1
  selector:
    matchLabels:
      app: productmicroservice 
  template:
    metadata:
      labels:
        app: productmicroservice 
    spec:
      containers:
      - name: mehzancontainerregistry
        image: mehzancontainerregistry.azurecr.io/productmicroservice:latest
        imagePullPolicy: IfNotPresent       
      imagePullSecrets:
       - name: acr-secret

And run it in the following kubectlcommand as follow:

 

kubectl apply -f path\filename.yml

I have saved the script in acr-secret.yml in the path C:\Utvecklingprogram\Kubernetes\

And run it as following  command line from my local machine

 

kubectl apply -f C:\Utvecklingprogram\Kubernetes\acr-secret.yml

If it succeed the output shall be: pod/productmicroservice created

where name: productmicroservice is the pod name of productmicroservice in the kubernetes (shall be seen in KS8: dashboard) and containers: name: mehzancontainerregistry   is the ContainerRegistry name we have created in Azure (the name should be lower case). The image: mehzancontainerregistry.azurecr.io/productmicroservice:latest  is the image in the Container Registry Service from Azure which we have imported from my Dockerhub.

Test the pulling image from Kubernetes (aks).

Connect to the K8s dashboard (by starting Octant from your local machine) If you have not installed Octant look to the my post: azure-kubernetes-service-aks

Start Octant from your local machine(start menu) and click on the  Workloads: Pods, the following shall be displayed:

azure podsPod: productmicroservice is pulling from ACR and Running.

Look to the Config and Storage: Secret:

azure secrets
Config and Storage: Secrets: acr-secret is ok

 

 

 

 

 

As you see the acr-secret is created in your KS8 service.

Look to the Events:

azure events
Event shows pod: productmicroservice is created 

If we check the Services on the KS8: dashboard then we see this part is empty, because we have created only a kubernets (microservice-aks) without any  “Service and Ingress”.  Now we want to have Service and test application (productmicroservice). We can create Service And Ingress as  described  in my post: Azure Kubernetes Service (AKS)   In the section: deploy the first Application.

 

Now go to the KS8 dashboard : Discovery and Load Balancing: Services then you can see that productmicroservice is created as following image:

azure services
Service productmicroservice is created and has External IP: 4.225.208.21

Open browser with the external IP : 4.225.208.21, then the Swagger UI is displayed for ProductMicroservice as following:

azure api
Swagger UI inj the productmicroservice: image pulled from ACR.

That is all.

We have created ACR, imported image from dockerhub, created AKS Service and configured, authorized to pull from ACR and tested it with KS8:dashboard.

In the end Cleanup all resources

When you are finished,  delete all created resources in your Azure account. AKS creates three additional resource groups. Make sure to delete them too. Delete all resource groups.

Conclusion

In this post I have created an Azure Container Registry (ACR) in Azure Portal and Imported image from Dockerhub to ACR. Then I have created an Azure Kubernetes Service (AKS) and Authorized it to access to pull image from ACR. In the end I have tested it in KS8 dashboard (Helm octant), which shows the Swagger UI is uploaded from my application (ProductMicroservices).

All the Source code is  on my GitHub.

Read about Alternative 2: Uploading Image to ACR from Azure DevOps Pipelines here. 

About the author

 

Mehrdad is Consultant as System developer and Architect in Microsoft stack: .NET Platform, C#, , .NET Core, Micoroservices, Docker Containers, Azure, Kubernetes Service, DevOps , CI/CD, SQL Server, APIs, Websites, and more
In Frontend: HTML, JavaScript, CSS, jQuery, React, and more.
In addition I can build Websites by WordPress.

Frilanskonsult Mehrdad

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