A pipeline builds a container image (Image1) and pushes it to an Azure Container Registry (ACR1). Image1 is based on a base image stored in Docker Hub. Ensure Image1 is rebuilt automatically whenever the base image is updated. What should you do?

Creating and running an Azure Container Registry (ACR) task, specifically a acr build task with a base image trigger, is the correct solution. ACR tasks can monitor a base image in Docker Hub (or another registry) and automatically rebuild dependent images in ACR1 when the base image changes. This automates the update process. Enabling the Azure Event Grid resource provider and subscribing to registry events would notify you of changes but wouldn't automatically rebuild the image. Adding a Docker Hub service connection to Azure Pipelines allows access to Docker Hub but doesn't inherently trigger rebuilds based on base image updates. Creating a service hook in Azure DevOps would integrate with other services but isn't designed for automatic base image-triggered container image rebuilds within ACR.