Configure and Secure Container Registries

This guide covers selecting, configuring, and operating container registries. Managed options include AWS ECR, Google Artifact Registry, Azure Container Registry, and Docker Hub. Self-hosted choices include Harbor, Sonatype Nexus, JFrog Artifactory, and the Docker Registry. The comparison considers cloud integration, supported artifact formats, security features, and operational complexity; Docker Hub rate limits also matter when planning production image pulls.

Security topics include authentication, access control, encryption, vulnerability scanning, and image signing. Examples use ECR password-based Docker authentication, scan-on-push repository configuration, Docker Content Trust, and Cosign. These are separate mechanisms: successfully logging in or signing an image does not establish that a deployment verifies the intended signer or enforces a vulnerability policy.

Use this guide when planning registry infrastructure or connecting an existing registry to delivery tooling. It addresses both a lightweight image store and richer artifact-management platforms. Harbor examples illustrate service configuration, persistent storage, TLS, scanning, logging, and supporting services. They are partial configurations tied to a particular version, so they require validation against the chosen installation method and release.

Do not copy example passwords, hostnames, storage paths, or historical image and action versions into production. Troubleshooting shortcuts such as disabled certificate checking, insecure registries, or deleting Docker credential configuration should not become normal security policy or a blanket repair action. Preserve existing credentials and configuration before making a targeted change, and investigate TLS failures rather than treating a bypass as successful verification.

Inputs include a selected registry, account or project scope, authentication method, storage backend, TLS configuration, and image naming and retention policy. Kubernetes integration uses a dockerconfigjson Secret referenced through imagePullSecrets on a ServiceAccount. Deployment configuration then names that ServiceAccount, image, pull policy, and resource limits.

GitLab CI and GitHub Actions examples build and push images, including commit-specific tags and multi-platform builds. Their credentials and build dependencies must be supplied through the actual environment. Image publication is an output of a configured pipeline, not an action already performed by this guide.

For certificate investigation, use the following pattern after replacing the placeholder hostname:

openssl s_client -connect registry.company.com:443 -servername registry.company.com

Maintenance covers untagged-image cleanup, retention inspection, Harbor API operations and webhooks, monitoring, caching, replication, storage backends, and network tuning. Review deletion candidates before applying cleanup. Keep registry data backed up, monitor storage usage, and maintain security updates. Performance tuning and registry mirrors must remain compatible with the deployment's trust and access requirements.