Azure Container Registry (ACR) is a managed Docker registry service that allows you to store and manage container images for Azure deployments. Publishing an image to ACR involves several key steps that every Azure developer should understand.
First, you need to create an Azure Container Registry …Azure Container Registry (ACR) is a managed Docker registry service that allows you to store and manage container images for Azure deployments. Publishing an image to ACR involves several key steps that every Azure developer should understand.
First, you need to create an Azure Container Registry instance through the Azure Portal, Azure CLI, or ARM templates. When creating the registry, you select a SKU (Basic, Standard, or Premium) based on your storage and throughput requirements.
Before pushing an image, you must authenticate to the registry. The most common method uses the Azure CLI command 'az acr login --name <registry-name>', which retrieves credentials and logs you into the registry. Service principals or managed identities can also be used for automated scenarios.
Next, you need to tag your local Docker image with the fully qualified registry path. The format follows: <registry-name>.azurecr.io/<image-name>:<tag>. For example, if your registry is named 'myregistry' and your image is 'myapp', you would use: 'docker tag myapp myregistry.azurecr.io/myapp:v1'.
Once tagged, push the image using the standard Docker push command: 'docker push myregistry.azurecr.io/myapp:v1'. The image layers are uploaded to ACR and stored securely.
Alternatively, ACR Tasks provides a feature called Quick Tasks that builds and pushes images in the cloud using 'az acr build --registry <registry-name> --image <image-name>:<tag> .' This approach eliminates the need for a local Docker installation.
After publishing, you can verify the image exists using 'az acr repository list' or 'az acr repository show-tags' commands. The image is now ready for deployment to Azure services like Azure Kubernetes Service, Azure Container Instances, or Azure App Service.
Best practices include using image scanning for vulnerabilities, implementing geo-replication for high availability, and applying retention policies to manage storage costs.
Publish an Image to Azure Container Registry
Why It Is Important
Publishing container images to Azure Container Registry (ACR) is a fundamental skill for Azure developers. ACR serves as a private registry for storing and managing container images, enabling secure deployment pipelines and integration with Azure services like Azure Kubernetes Service (AKS), Azure Container Instances (ACI), and Azure App Service. Understanding this process is essential for the AZ-204 exam and real-world cloud development.
What Is Azure Container Registry?
Azure Container Registry is a managed, private Docker registry service based on the open-source Docker Registry 2.0. It allows you to: - Store and manage container images securely - Build, store, and deploy container images within Azure - Integrate with existing container development and deployment pipelines - Use geo-replication for global distribution
How It Works
The process of publishing an image to ACR involves several steps:
1. Create an Azure Container Registry: Use Azure CLI: az acr create --resource-group myResourceGroup --name myRegistry --sku Basic
2. Log in to the Registry: az acr login --name myRegistry
3. Tag Your Local Image: Tag the image with the ACR login server name: docker tag myimage:v1 myregistry.azurecr.io/myimage:v1
4. Push the Image: docker push myregistry.azurecr.io/myimage:v1
5. Verify the Upload: az acr repository list --name myRegistry --output table
Authentication Methods
- Azure CLI: Uses az acr login for interactive authentication - Service Principal: For automated pipelines and CI/CD - Admin Account: Not recommended for production but useful for testing - Managed Identity: For Azure services accessing ACR
ACR Tasks
ACR Tasks can automate image building in the cloud: az acr build --registry myRegistry --image myimage:v1 . This builds and pushes the image in one command, eliminating the need for a local Docker installation.
Exam Tips: Answering Questions on Publishing Images to ACR
Key Points to Remember:
1. Login Server Format: Always remember the format is <registryname>.azurecr.io
2. SKU Differences: Know the three tiers - Basic, Standard, and Premium. Premium supports geo-replication and private endpoints.
3. Command Order: The sequence is login, tag, then push. Questions may test if you know the correct order.
4. ACR Build vs Docker Push: Understand when to use az acr build versus traditional docker build and push workflows.
5. Authentication Scenarios: Service principals are preferred for CI/CD pipelines. Admin accounts should be avoided in production scenarios.
6. Tagging Convention: Images must be tagged with the full ACR login server path before pushing.
7. Repository Commands: Know commands like az acr repository list and az acr repository show-tags for verification.
Common Exam Scenarios:
- Choosing the correct authentication method for a given scenario - Identifying the proper sequence of commands to push an image - Selecting the appropriate SKU based on requirements like geo-replication - Troubleshooting failed pushes due to incorrect tagging or authentication
Practice Command: Be familiar with the complete workflow from creating a registry to pushing and verifying an image.