[Docker] OCI and Registries - eeeemune/Infra-Notes GitHub Wiki

💚 OCI (Open Container Images) and Registries

💛 What is OCI?

  • OCI stands for Open Container Initiative
  • It defines open standards for container image formats and runtimes.
  • OCI ensures interoperability across different tools, platforms, and registries.

💛 OCI Images

  • OCI images follow a standardized format (like Docker images).
  • These images include:
    • A manifest (describes the image layers),
    • Configuration (runtime settings),
    • Layers (compressed filesystems),
    • Signatures (for trust/security).

💛 OCI Registries

  • Registries store and serve OCI-compliant images.
  • Common OCI-compatible registries:
    • Docker Hub
    • GitHub Container Registry (ghcr.io)
    • Amazon ECR
    • Google Artifact Registry
    • Azure Container Registry
  • You can push and pull Helm charts and other artifacts (like WASM modules) as OCI objects.

💛 Helm + OCI

  • Helm 3+ supports storing charts in OCI registries.

  • Example:

    helm chart save ./mychart ghcr.io/myuser/mychart:v1
helm chart push ghcr.io/myuser/mychart:v1
helm chart pull ghcr.io/myuser/mychart:v1
helm chart export ghcr.io/myuser/mychart:v1

🤍 Why Use OCI for Helm Charts?

  • Versioned and immutable chart storage.
  • Uniform tooling and access control across images & charts.
  • Aligns with existing CI/CD pipelines using OCI tools.

💛 References