How to Migrate Azure Container Registry Artifacts to Vultr Container Registry

Azure Container Registry (ACR) is Microsoft's managed Docker registry service built on the open-source Docker Registry 2.0. While ACR integrates tightly with Azure services, organizations often migrate to alternative registries for cost optimization, multi-cloud flexibility, or simpler management. Vultr Container Registry offers a straightforward, globally distributed solution with predictable pricing and easy integration with container orchestration platforms.

This guide explains how to migrate container images from Azure Container Registry to Vultr Container Registry using Docker and Skopeo, covering authentication, transfer, verification, and cutover.

Prerequisites

Before you begin, you need to:

• Deploy an Ubuntu 24.04 instance to use as your migration workstation.
• Install Docker on the workstation.
• Install the Azure CLI and authenticate with an account that has pull access to your ACR.
• Provision a Vultr Container Registry and note the registry URL, username, and API key.

Authenticate with Azure Container Registry

Connect your workstation to ACR so Docker can pull images. Azure offers multiple authentication methods depending on your security requirements.

1. Sign in to Azure CLI.

   CONSOLE

   Copy

   $ az login

   Explain Code

   Powered by Vultr AgentBeta

   Follow the browser prompts to complete authentication.

2. Authenticate Docker with your ACR instance. Replace ACR-NAME with your registry name (without the .azurecr.io suffix).

   CONSOLE

   Copy

   $ az acr login --name ACR-NAME

   Explain Code

   Powered by Vultr AgentBeta

   Output:

   Login Succeeded

   Note

   If you prefer token-based authentication or need to authenticate from CI/CD pipelines, you can enable the admin user or use a service principal.

Inventory Your ACR Repositories

Before migrating, catalog all repositories and their tags in your ACR. This inventory helps you track progress and ensures no images are missed during the transfer.

1. List all repositories in your ACR.

   CONSOLE

   Copy

   $ az acr repository list --name ACR-NAME --output table

   Explain Code

   Powered by Vultr AgentBeta

   Output:

   Result
   ---------------
   frontend
   backend-api
   worker-service
   nginx-proxy

2. View tags for a specific repository.

   CONSOLE

   Copy

   $ az acr repository show-tags --name ACR-NAME --repository frontend --output table

   Explain Code

   Powered by Vultr AgentBeta

   Output:

   Result
   --------
   v1.0.0
   v1.1.0
   latest

3. List all images with their tags across repositories.

   CONSOLE

   Copy

   $ for repo in $(az acr repository list --name ACR-NAME -o tsv); do
       echo "=== $repo ==="
       az acr repository show-tags --name ACR-NAME --repository $repo -o tsv
     done

   Explain Code

   Powered by Vultr AgentBeta

   Document this inventory before proceeding with migration.

Authenticate with Vultr Container Registry

Configure Docker to push images to your Vultr registry. You'll need the registry URL and API credentials from the Vultr Console.

1. Log in to the Vultr Console.

2. Navigate to Products.

3. Select Container Registry.

4. Select your registry and note the Registry URL, Username, and API Key from the overview page.

5. Authenticate Docker with the Vultr registry. Replace VULTR-REGISTRY-URL, USERNAME, and API-KEY with your credentials. The registry URL should not include https://.

   CONSOLE

   Copy

   $ docker login VULTR-REGISTRY-URL -u USERNAME -p API-KEY

   Explain Code

   Powered by Vultr AgentBeta

   Output:

   Login Succeeded

Migrate Images Using Docker

The standard migration workflow involves pulling images from ACR to your workstation, retagging them with the Vultr registry URL, and pushing to the destination. You can migrate individual images or automate the entire registry transfer with a script.

Migrate a Single Image

1. Pull an image from ACR. Replace ACR-NAME with your Azure registry name.

   CONSOLE

   Copy

   $ docker pull ACR-NAME.azurecr.io/frontend:v1.0.0

   Explain Code

   Powered by Vultr AgentBeta

2. Tag the image for Vultr. Replace VULTR-REGISTRY-URL with your Vultr registry URL.

   CONSOLE

   Copy

   $ docker tag ACR-NAME.azurecr.io/frontend:v1.0.0 VULTR-REGISTRY-URL/frontend:v1.0.0

   Explain Code

   Powered by Vultr AgentBeta

3. Push the image to Vultr.

   CONSOLE

   Copy

   $ docker push VULTR-REGISTRY-URL/frontend:v1.0.0

   Explain Code

   Powered by Vultr AgentBeta

Migrate All Repositories

Automate the migration of all images using a shell script.

1. Create a migration script.

   CONSOLE

   Copy

   $ nano acr_to_vultr.sh

   Explain Code

   Powered by Vultr AgentBeta

2. Add the following content. Replace ACR-NAME and VULTR-REGISTRY-URL with your values.

   BASH

   Copy

   #!/bin/bash
   
   ACR_NAME="ACR-NAME"
   VULTR_URL="VULTR-REGISTRY-URL"
   
   for repo in $(az acr repository list --name "$ACR_NAME" -o tsv); do
       for tag in $(az acr repository show-tags --name "$ACR_NAME" --repository "$repo" -o tsv); do
           src="${ACR_NAME}.azurecr.io/${repo}:${tag}"
           dest="${VULTR_URL}/${repo}:${tag}"
           
           echo "Migrating $src -> $dest"
           docker pull "$src"
           docker tag "$src" "$dest"
           docker push "$dest"
       done
   done
   
   echo "Migration complete."

   Explain Code

   Powered by Vultr AgentBeta

   Save and close the file.

3. Make the script executable and run it.

   CONSOLE

   Copy

   $ chmod +x acr_to_vultr.sh
   $ ./acr_to_vultr.sh

   Explain Code

   Powered by Vultr AgentBeta

Verify Migrated Images

After migration, validate that images transferred without corruption by comparing SHA256 digests between registries and running test containers from Vultr.

1. Open the Vultr Container Registry in the Vultr Console and verify your repositories appear under the Repositories tab.

2. Compare image digests between ACR and Vultr to confirm integrity.

   • Get the digest from ACR:

     CONSOLE

     Copy

     $ az acr manifest list-metadata --name frontend --registry ACR-NAME --query "[0].digest" -o tsv

     Explain Code

     Powered by Vultr AgentBeta

   • Get the digest from Vultr:

     CONSOLE

     Copy

     $ docker pull VULTR-REGISTRY-URL/frontend:v1.0.0
     $ docker inspect VULTR-REGISTRY-URL/frontend:v1.0.0 --format='{{index .RepoDigests 0}}' | cut -d'@' -f2

     Explain Code

     Powered by Vultr AgentBeta

   The digests should match, confirming the image transferred without corruption.

3. Run a test container from the Vultr registry.

   CONSOLE

   Copy

   $ docker run --rm VULTR-REGISTRY-URL/frontend:v1.0.0 echo "Container works"

   Explain Code

   Powered by Vultr AgentBeta

   Output:

   Container works

Cutover to Vultr Container Registry

After images are verified on Vultr, update your Dockerfiles, orchestration configs, and CI/CD pipelines to use the new registry. This section covers common deployment scenarios including Docker Compose and Kubernetes.

Update Dockerfiles

Change base image references from ACR to Vultr.

• Before:

  DOCKERFILE

  Copy

  FROM myacr.azurecr.io/base-image:latest

  Explain Code

  Powered by Vultr AgentBeta

• After:

  DOCKERFILE

  Copy

  FROM VULTR-REGISTRY-URL/base-image:latest

  Explain Code

  Powered by Vultr AgentBeta

Update Docker Compose Files

1. Update the image references in your compose file.

   YAML

   Copy

   services:
     app:
       image: VULTR-REGISTRY-URL/frontend:v1.0.0

   Explain Code

   Powered by Vultr AgentBeta

2. Redeploy the services.

   CONSOLE

   Copy

   $ docker compose down
   $ docker compose up -d

   Explain Code

   Powered by Vultr AgentBeta

Update Kubernetes Deployments

1. Modify your deployment manifests.

   YAML

   Copy

   spec:
     containers:
     - name: frontend
       image: VULTR-REGISTRY-URL/frontend:v1.0.0

   Explain Code

   Powered by Vultr AgentBeta

2. If your cluster requires authentication, create an image pull secret. Replace the placeholders with your Vultr registry credentials.

   CONSOLE

   Copy

   $ kubectl create secret docker-registry vultr-registry \
       --docker-server=VULTR-REGISTRY-URL \
       --docker-username=USERNAME \
       --docker-password=API-KEY \
       --namespace=NAMESPACE

   Explain Code

   Powered by Vultr AgentBeta

3. Reference the secret in your deployment.

   YAML

   Copy

   spec:
     imagePullSecrets:
     - name: vultr-registry

   Explain Code

   Powered by Vultr AgentBeta

4. Apply the updated manifests.

   CONSOLE

   Copy

   $ kubectl apply -f deployment.yaml

   Explain Code

   Powered by Vultr AgentBeta

Update CI/CD Pipelines

Replace ACR authentication and image references in your pipeline configurations.

• Before (Azure DevOps / GitHub Actions):

  YAML

  Copy

  - run: az acr login --name myacr
  - run: docker push myacr.azurecr.io/app:${{ github.sha }}

  Explain Code

  Powered by Vultr AgentBeta

• After:

  YAML

  Copy

  - run: docker login VULTR-REGISTRY-URL -u ${{ secrets.VULTR_USER }} -p ${{ secrets.VULTR_KEY }}
  - run: docker push VULTR-REGISTRY-URL/app:${{ github.sha }}

  Explain Code

  Powered by Vultr AgentBeta

Conclusion

You have successfully migrated your container images from Azure Container Registry to Vultr Container Registry. This guide covered authenticating with both registries, transferring images using Docker and Skopeo, verifying integrity through digest comparison, and updating your deployments for the cutover. Your container workloads now benefit from Vultr's predictable pricing and global infrastructure. For more details on managing your registry, see the Vultr Container Registry documentation.