The Open Container Initiative (OCI) is a Linux Foundation project, started in June 2015 by Docker, CoreOS, and the maintainers of appc to design open standards for operating-system-level virtualization (software containers).[1][2][3] At launch, OCI was focused on Linux containers and subsequent work has extended it to other operating systems.[4][5][6]
There are currently three OCI specifications in development and use: the Runtime Specification (runtime-spec), the Image Specification (image-spec), and the Distribution Specification (distribution-spec).
The OCI organization includes the development of runc, which is the reference implementation of the runtime-spec,[7][8] a container runtime that implements their specification and serves as a basis for other higher-level tools. runc was first released in July 2015 as version 0.0.1[9] and it reached version 1.0.0 on July 19, 2017.[10]
The OCI Image Format Project was split out from the Runtime Project into its own specification on March 23, 2016.[11] The image-spec is a software shipping container image format spec (OCI Image Format) that reached version 1.0.0 on July 19, 2017.[12]
The OCI Distribution Spec Project defines the distribution-spec, an API protocol to facilitate and standardize the distribution of content. The distribution-spec was created on March 8, 2018 from a Proposal for a JSON Registry API V2.1.[13] The distribution-spec reached version 1.0.0 on April 26, 2021.[14]