image manifest
also: manifest, Docker manifest, OCI manifest, image configuration
A metadata file that describes the contents, layers, and configuration of a container image, typically in JSON format. It ensures image integrity and enables proper distribution and deployment across systems.
An image manifest is a JSON document that serves as a blueprint for a container image, listing all its layers, their digests (cryptographic hashes), and configuration details. When you pull a container image from a registry like Docker Hub or Kubernetes, the manifest is consulted first to verify which specific layers need to be downloaded and assembled.
The manifest includes critical metadata such as the image architecture, OS type, layer sizes, and a reference to the image configuration blob. For example, a manifest might specify that an image consists of three layers: a base Linux filesystem, a runtime environment, and application code—each identified by its SHA256 hash.
Modern container systems support both the Docker Image Manifest V2 and the OCI (Open Container Initiative) Image Manifest format. These standards ensure that images built on one system can be reliably pulled and run on any other system, and they enable content-addressable storage where identical layers are never duplicated in a registry.