When building container images on Miget using Docker Engine, you might need to pull base images from a private Docker registry, such as a private repository on Docker Hub. To enable the Miget builder to authenticate and access your private registry, you can set the following environment variables in Settings -> Vars. These credentials allow the builder to log in to your private registry during the build process, ensuring that it can fetch your private images. Example Dockerfile: 
FROM my-private-registry/my-project/my-image:latest

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ENV Variables to Set

For example, to allow Miget to access Docker Hub (example below) or other private registries, set the following variables:
  • EXTERNAL_REGISTRY_URL=docker.io
  • EXTERNAL_REGISTRY_USERNAME=<your_username>
  • EXTERNAL_REGISTRY_PASSWORD=<docker_hub_token>
For security reasons, it’s recommended to create a Read-Only token for authentication. This ensures that the Miget builder can pull images but cannot push any images to the external registry, maintaining stricter access control.

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Supported Registries

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Amazon Elastic Container Registry (ECR)

  • EXTERNAL_REGISTRY_URL=$AWS_ACCOUNT_ID.dkr.ecr.$AWS_REGION.amazonaws.com Ensure the $AWS_ACCOUNT_ID and $AWS_REGION values match those in your AWS account.

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Azure Container Registry (ACR)

  • EXTERNAL_REGISTRY_URL=$REGISTRY_NAME.azurecr.io Replace $REGISTRY_NAME with your registry’s name in Azure.

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Docker Hub

  • EXTERNAL_REGISTRY_URL=docker.io Make sure you own the namespace (you pull from) specified in the Dockerfile

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DigitalOcean Container Registry

  • EXTERNAL_REGISTRY_URL=registry.digitalocean.com

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GitHub Container Registry (GHCR)

  • EXTERNAL_REGISTRY_URL=ghcr.io

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Quay.io

  • EXTERNAL_REGISTRY_URL=quay.io
By configuring these environment variables, Miget can securely log in to your private registry and pull the required images during your builds.