containerd Image Pull Authentication Error — Quick Fix

In this tutorial, you'll learn about containerd image pull authentication error. We cover key concepts, practical examples, and best practices.

The Problem

Pulling an image from a private registry with containerd fails with an authentication error. The credentials may be missing, expired, or stored in the wrong location. containerd returns an unauthorized or denied error.

Error example:

ctr: failed to resolve reference "registry.example.com/app:latest"
ctr: authorizer: unauthorized: authentication required
ctr: failed to pull image: denied: access forbidden

The Fix

Step 1: Check the containerd registry configuration

WRONG — using Docker's config.json location for containerd:

# containerd uses its own config, not Docker's ~/.docker/config.json

RIGHT — configure credentials in /etc/containerd/config.toml:

[plugins."io.containerd.grpc.v1.cri".registry.configs]
  [plugins."io.containerd.grpc.v1.cri".registry.configs."registry.example.com".auth]
    username = "myuser"
    password = "mypassword"
    # Or use auth token
    # auth = "base64-encoded-user:password"

Restart containerd after making changes:

systemctl restart containerd

Step 2: Test the pull

WRONG — trying to pull without verifying credentials:

# Always test after updating credentials

RIGHT — verify the pull succeeds:

ctr -n k8s.io image pull registry.example.com/app:latest

Output:

registry.example.com/app:latest: resolved |++++++++++++++++++++++++++++++++++++++|
manifest: digest: sha256:abc123 size: 1234

Use DodaTech's Registry Connectivity Tester to validate credentials, TLS certificates, and registry accessibility from any containerd node.

Prevention Tips

• Use ~/.docker/config.json with docker login and configure containerd to read it
• Store registry credentials as Kubernetes imagePullSecrets for production
• Rotate registry passwords regularly and update containerd configs
• Use a registry pull-through cache to reduce authentication failures
• Use DodaTech's Image Registry Manager to centralize credential management

Common Mistakes with pull auth

1. Mixing let bindings with <- bindings in do notation, producing type errors
2. Overlapping type class instances that cause GHC to reject the program with ambiguous dispatch errors
3. Non-exhaustive pattern matches that compile with warnings then crash at runtime

These mistakes appear frequently in real-world CONTAINERD code. DodaTech's contributors have identified these patterns through analysis of open-source projects and production systems.

Practice Exercise

Write a pure function that safely divides two integers using Maybe, then test it with edge cases like division by zero and negative numbers.

This exercise reinforces the concepts covered in this guide. Try implementing it before checking online solutions.

FAQ

Related: DodaTech's Runtime Security Scanner audits container runtime configurations, including registry credential storage and TLS settings, to identify misconfigurations.