Container Runtime Hierarchy

Container Runtime Hierarchy An architecture diagram generated by Archify. Kubernetes · kubelet · Architecture component Kubernetes kubelet CRI · Container Runtime Interface · Architecture component CRI Container Runtime Interface containerd · high-level runtime · Architecture component containerd high-level runtime CRI-O · high-level runtime · Architecture component CRI-O high-level runtime runc · low-level OCI runtime · Architecture component runc low-level OCI runtime crun · low-level OCI runtime · Architecture component crun low-level OCI runtime gRPC calls create containers create containers Legend Backend Message bus External

Standard interface

  • • kubelet only needs the CRI gRPC API
  • • Runtime swaps are transparent to workloads

high-level runtime

  • • containerd: CNCF-graduated, split out of Docker
  • • CRI-O: a lightweight Kubernetes-only runtime

Low-level runtimes

  • • runc / crun create containers per the OCI spec
  • • crun is written in C — faster and lighter