Containerd is a daemon-based container runtime that manages the complete lifecycle of containers on a host system. It functions as a core orchestration backend, handling image distribution, storage, and process execution while adhering to industry-standard specifications for container execution and configuration.
The project is distinguished by its modular, plugin-based architecture, which allows for the extension of storage, runtime, and networking capabilities without requiring a full daemon recompile. It utilizes a shim-based execution model to delegate low-level operations, ensuring isolation and support for diverse environments. Furthermore, it employs content-addressable storage for efficient image management and provides a gRPC-based interface for programmatic control by external infrastructure applications.
Beyond its core execution duties, the project covers a broad capability surface including comprehensive filesystem management, secure resource isolation, and advanced observability. It supports complex deployment requirements through features like container checkpointing, hardware resource exposure, and flexible network configuration. Security is enforced through image verification, kernel-level isolation policies, and support for unprivileged container execution.
The project provides extensive documentation and tooling, including command-line utilities with shell completion and automated test suites for validating runtime interface compliance.
