Interoperability of open-source tools: the emergence of interfaces

In the past years, Kubernetes has been the nucleus of container orchestration frameworks. Numerous tools have been developed to extend Kubernetes capabilities and enhance its features. Over time, tools with similar functionalities would have fundamentally different implementations and practices to converge with the Kubernetes components. The emergence of shared standards and a set of best practices became imperative.

This blog post will focus on the evolution of interfaces within the Kubernetes landscape, including networking, storage, service mesh and cluster provisioning. As well, an emphasis will be placed on why the interoperability of open-source tools is pivotal in the modern infrastructure.

The Theoretical Past

Kubernetes is widely known for its adaptability and flexibility to run containerised workloads with pre-defined technical requirements. One of its goals is to efficiently supply the ecosystem crucial for application execution while reducing its footprint in the cluster. To reach this state of the art, complex challenges needed solutionizing, such as support of different hardware and networking systems. Henceforth, plugins for container runtimes and network interfaces were developed to reach a smoother transition between VM native workloads and containerized applications.

Historically, interface adoption has been encountered in the early stages of Kubernetes evolution. For example, Container Runtime Interface (CRI) was introduced in its alpha release in Kubernetes v1.5 , while Container Network Interface (CNI) was announced as a CNCF hosted project in 2017 . These projects define a solid set of guidelines to enhance the portability and connectivity of containerized applications.