The Open Container Initiative (OCI) released the first versions of its open source container runtime and image format specification.

OCI, which runs inside the Linux Foundation, said the specifications support container portability across different implementations, including compliant operating systems and platforms. Companies using the specifications can develop, package, and sign application containers, then run them in a variety of container engines.

The runtime specification lays out rules for how a container filesystem bundle is stored on a local disk for access by a compatible runtime agent. A container runtime provides an application programming interface (API) and tools that abstract low-level technical details in the container.

The image format specification targets the unpacking of OCI-compliant images in a filesystem bundle. Container images are a set of filesystem layers that make up the container content.

“Basically, as long as images follow this specification, it should enable anyone to build tools that will work with the images and have the resulting images be compatible with any compliant runtime,” explained Joe Brockmeier, senior evangelist for Linux Containers at Red Hat, in a blog post.

The initial specification has been nearly two years in the making. OCI began the push in mid-2015, releasing drafts of its charter and technical specifications. Docker Inc. was instrumental in the initial work, having donated its runC container format and runtime to the cause.

The organization has attracted more than 40 members, including a number of heavy hitters in the container ecosystem. This includes Amazon Web Services (AWS), AT&T, Dell, Docker Inc., Google, IBM, Intel, Microsoft, Oracle, Verizon, and VMware.

Moving forward, OCI said “there is still work to be done.” This includes current efforts on a certification program to show specification conformance for different implementations. The certification program is expected to be ready by later this year and allow for official OCI certification of platforms.

OCI members also hinted at additional support for other platforms, specification functionality, and projects. This includes work on adding support for Kubernetes container orchestration.

“Combined with efforts to create a formal certification program later this year, OCI is bringing a set of common, minimal, open standards, and specifications around container technology to a reality,” the organization noted.

Various communities are racing to provide support for the burgeoning container space. A 451 Research report forecast the container ecosystem to grow from $762 million in revenues last year to nearly $2.7 billion in 2020. Forrester Research estimates that 31 percent of all enterprise IT organizations have already deployed containers.