containerd — The Industry-Standard Container Runtime

What it is

containerd is the core container runtime that powers both Docker and Kubernetes. It manages the complete container lifecycle: pulling images from registries, storing them on disk, creating container filesystems, executing processes inside containers, and supervising them until termination. It is a graduated CNCF project and the default runtime for most Kubernetes distributions.

containerd is designed for infrastructure engineers, platform teams, and anyone running containers in production. While Docker provides a user-friendly CLI, containerd is the lower-level engine that Docker calls under the hood.

How it saves time or tokens

containerd provides a stable, minimal runtime API that avoids the overhead of Docker's full daemon. For Kubernetes clusters, using containerd directly (without Docker) reduces memory footprint and startup latency per node. For CI/CD pipelines, the lighter runtime means faster container creation and image pulls, which translates to shorter build times across hundreds of daily pipeline runs.

How to use

1. Install containerd on Linux:

# Ubuntu/Debian
sudo apt install containerd.io

# Or from GitHub releases
curl -LO https://github.com/containerd/containerd/releases/download/v1.7.0/containerd-1.7.0-linux-amd64.tar.gz
sudo tar -C /usr/local -xzf containerd-1.7.0-linux-amd64.tar.gz

1. Start the containerd daemon:

sudo systemctl enable --now containerd

1. Use ctr (the containerd CLI) to pull and run images:

sudo ctr images pull docker.io/library/nginx:latest
sudo ctr run docker.io/library/nginx:latest my-nginx

Example

Pull an image and inspect its layers with the containerd CLI:

# Pull an image
sudo ctr images pull docker.io/library/alpine:latest

# List images
sudo ctr images ls

# Run a container
sudo ctr run --rm docker.io/library/alpine:latest test-container echo 'Hello from containerd'

# Check running containers
sudo ctr containers ls

For Kubernetes, containerd is configured as the CRI runtime in kubelet's configuration file.

Related on TokRepo

• AI Tools for DevOps — DevOps tools for container orchestration and deployment pipelines
• AI Tools for Self-Hosted — Self-hosted infrastructure tools including container runtimes

Common pitfalls

• The ctr CLI is a debugging tool, not a production interface. Use nerdctl for a Docker-compatible CLI experience on top of containerd.
• containerd does not include a built-in image builder. Use BuildKit or kaniko for building container images in containerd-only environments.
• Kubernetes switched from Docker to containerd as the default runtime. If you are migrating, ensure your container images do not depend on Docker-specific features like Docker socket mounting.
• Always check the official documentation for the latest version-specific changes and migration guides before upgrading in production environments.
• For team deployments, establish clear guidelines on configuration and usage patterns to ensure consistency across developers.