A container registry is a service designed to store, manage, and distribute container images. It functions as a centralized repository that integrates into CI/CD pipelines, providing deployment environments with consistent access to application artifacts. It enables version control and access management for containerized software.
The registry operates via a REST API where clients like docker or skopeo perform push and pull operations. It stores image manifests and filesystem layers separately. By managing these layers, the registry ensures that only unique data is stored, significantly reducing storage requirements through deduplication.
Registries are essential for automating deployments and securing the software supply chain. While Docker Hub is the default for public images, private registries are used to host proprietary code, perform vulnerability scanning, and ensure high availability within local networks.
How it works
When a developer executes docker push my-registry.local/api-service:latest, the client authenticates and uploads the image layers. If the registry already contains a specific layer from a previous build, it skips the upload, optimizing both bandwidth and time during the continuous integration process.