containerbildformater

Containerbildformater, in English often referred to as container image formats, describe the specifications used to package, store, and distribute container images. An image encapsulates the file system, configuration data, and metadata that container runtimes such as Docker, containerd, or CRI-O load to run a container. The format determines how layers are stored, how dependencies are tracked, and how images are identified and retrieved.

The two main standards are the Open Container Initiative (OCI) image format and the Docker image format. The OCI specification defines a portable, runtime-agnostic layout for image data, including image blobs (layers), a configuration blob, and a manifest that describes how to assemble the image. The Docker format originated with Docker’s own tooling and later aligned with OCI in many areas, while still supporting some legacy characteristics. A key feature is the use of content-addressable storage, where each blob and manifest is addressed by a cryptographic digest.

Images are often distributed via registries and can include multiple architecture variants. Multiplatform images use manifest lists to select the appropriate image for a given platform. This interoperability allows different runtimes and registries to share images, while maintaining reproducibility through fixed digests and versioned manifests.

Security and tooling play important roles in containerbildformater ecosystems. Image signing and verification, such as with Notary or Sigstore/Cosign, help ensure authenticity and integrity. Build and packaging tools (for example, Docker, Buildah, Kaniko) generate images in these formats, while runtime environments pull and verify them from registries.

See also: Open Container Initiative, Docker, container registry, image signing.