Troubleshoot a Linux service that fails to start
Collect unit state and logs before retrying a failed service; isolate configuration, permissions, dependencies, and port conflicts.
Read guide →TROUBLESHOOTING · FIELD GUIDES
Linux and DevOps troubleshooting
Evidence-led runbooks for common Linux, networking, CI/CD, Docker, Terraform, Kubernetes, firewall, and TLS problems.
Linux services
Linux storage
Troubleshoot a Linux server running out of disk space
Determine whether bytes or inodes are exhausted, locate the affected mount, and reclaim data through its owning application.
Read guide →Linux networking
Troubleshoot SSH connection refused on Linux
Trace hostname, route, destination port, listener, and firewall path to find where an SSH connection is rejected.
Read guide →Networking
Troubleshoot DNS resolution failures
Compare system lookups with direct resolver answers to isolate local configuration, upstream reachability, and record problems.
Read guide →Docker
Troubleshoot a Docker container that exits immediately
Capture container exit state and previous logs, then inspect launch command, environment names, mounts, and resource limits.
Read guide →CI/CD
Troubleshoot CI failure after a dependency update
Compare dependency and lockfile changes, runner versions, the first failed test, and upstream package availability.
Read guide →Terraform
Investigate an unexpected Terraform resource replacement
Read the plan’s replacement markers and compare configuration, state, provider version, workspace, and immutable attributes.
Read guide →Kubernetes
Troubleshoot a Kubernetes Pod that keeps restarting
Collect events, restart count, last termination reason, previous logs, probes, and resource limits to diagnose CrashLoopBackOff.
Read guide →Troubleshoot Kubernetes ImagePullBackOff
Check the exact image reference, registry response, pull credentials, namespace, node network, and platform compatibility.
Read guide →TLS and networking
Troubleshoot an expired or invalid TLS certificate
Inspect validity dates, hostname, chain, and clock at the endpoint that actually terminates TLS.
Read guide →Linux networking and security
Troubleshoot Linux firewall access safely
Confirm the service listener, active firewall manager, source path, and effective policy before a narrow rules change.
Read guide →Linux operations
Check Linux CPU, memory, and disk pressure
Collect time-stamped capacity and pressure data before restarting services or resizing a host.
Read guide →