Ubuntu 18.04 Docker permission denied on /var/run/docker.sock

📖 ~1 min read

Table of contents

1. Symptom & Impact
2. Environment & Reproduction
3. Root Cause Analysis
4. Quick Triage
5. Step-by-Step Diagnosis
6. Solution – Primary Fix
7. Solution – Alternative Approaches
8. Verification & Acceptance Criteria
9. Rollback Plan
10. Prevention & Hardening
11. Related Errors & Cross-Refs
12. References & Further Reading

Symptom & Impact

docker commands fail for non-root users with socket permission denied.

Environment & Reproduction

Issue appears after Docker installation or user account changes.

Root Cause Analysis

User missing docker group membership or incorrect socket ownership causes access failures.

Quick Triage

Check docker service status and current user group memberships.

Step-by-Step Diagnosis

Run id, ls -l /var/run/docker.sock, and systemctl status docker.

Solution – Primary Fix

Add user to docker group, relogin, and confirm socket permissions are correct.

Solution – Alternative Approaches

Use rootless Docker mode for stricter least-privilege operation.

Verification & Acceptance Criteria

docker ps works without sudo for authorized users.

Rollback Plan

Remove group membership and revert daemon config if policy requires sudo-only access.

Prevention & Hardening

Audit docker group membership regularly and enforce access controls.

Related Errors & Cross-Refs

Related to daemon startup failures and stale socket file ownership.

Related tutorial: View the step-by-step tutorial for Ubuntu 18.04 LTS.

View all Ubuntu 18.04 LTS tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Review Docker engine post-install and Ubuntu container runtime documentation.