Systemd Service Dependency Failures - Troubleshooting Guide
Systemd service dependency failures causing service startup issues? Quick steps to identify failed dependencies, resolve dependency problems, and restore service functionality.
Systemd Service Dependency Failures - Troubleshooting Guide
Service won't start, dependencies are failing, system is unstable. This guide gives you immediate steps to diagnose and fix systemd service dependency failures—now. No theory, just action.
For setting up monitoring to prevent this in the future, see Systemd Services and Dependencies Monitoring Guide after you've resolved the immediate crisis.
60-Second Triage
Run these commands in order:
# Step 1: Identify failed services (takes 5 seconds)
systemctl --failed
# Step 2: Check service dependencies (takes 10 seconds)
systemctl list-dependencies service-name --state=failed
# Step 3: View dependency errors
systemctl status service-name | grep -A 10 "Dependency"
# Step 4: Check dependency logs
journalctl -u dependency-name | tail -20
Common Dependency Failures and Quick Fixes
| Dependency Issue | Likely Cause | Quick Fix |
|---|---|---|
| Network service dependency | Network not ready | systemctl start network-online.target |
| Database dependency | Database not running | systemctl start mysql or systemctl start postgresql |
| Filesystem dependency | Filesystem not mounted | mount /mnt/required-fs |
| Socket dependency | Socket not created | systemctl start socket-name.socket |
Symptoms of Service Dependency Failures
Service dependency failures manifest in several ways:
- Service fails to start: Service shows "failed" or "inactive" status
- Dependency errors in logs: Journal logs show dependency-related errors
- Cascading service failures: Multiple services fail due to shared dependencies
- Service timeout: Service waits indefinitely for dependencies
Step-by-Step Troubleshooting
Step 1: Identify Failed Dependencies
When services fail due to dependencies:
-
Check Failed Services:
systemctl --failed -
View Service Dependencies:
systemctl list-dependencies service-name --state=failed -
Check Dependency Status:
for dep in $(systemctl show service-name -p Requires --value); do systemctl is-active $dep || echo "FAILED: $dep" done
Step 2: Investigate Dependency Issues
Once you identify failed dependencies:
-
Check Dependency Status:
systemctl status dependency-name -
Review Dependency Logs:
journalctl -u dependency-name | tail -50 -
Verify Dependency Configuration:
systemctl show dependency-name -p Requires,Wants,After
Step 3: Resolve Dependency Problems
When dependency issues are identified:
-
Start Failed Dependencies:
systemctl start dependency-name -
Verify Dependencies Are Running:
systemctl is-active dependency-name -
Restart Dependent Service:
systemctl restart service-name
Step 4: Prevent Future Dependency Failures
To prevent dependency failures:
-
Monitor Dependencies Continuously:
- Use Zuzia.app to monitor service dependencies
- Set up alerts for dependency failures
- Track dependency health
-
Verify Dependency Configuration:
- Review service dependency requirements
- Ensure dependencies start before dependent services
- Test dependency startup order
Automatic Detection with Zuzia.app
Zuzia.app automatically monitors service dependencies and detects failures:
- Checks dependency status every few minutes
- Detects failed dependencies immediately
- Sends alerts when dependencies fail
- Tracks dependency health over time
Set up dependency monitoring in Zuzia.app to prevent dependency failures:
- Add scheduled task:
systemctl list-dependencies service-name --state=failed - Configure alerts for dependency failures
- Monitor dependency health continuously
Best Practices for Preventing Dependency Failures
1. Monitor Dependencies Continuously
Don't wait for dependency failures:
- Use Zuzia.app for continuous dependency monitoring
- Set up alerts before dependencies become critical
- Review dependency status regularly
2. Verify Dependency Configuration
Ensure dependencies are configured correctly:
- Review service dependency requirements
- Test dependency startup order
- Verify dependencies start before dependent services
3. Respond Quickly to Dependency Failures
Have response procedures ready:
- Define escalation procedures for dependency failures
- Prepare dependency recovery procedures
- Test dependency recovery regularly
FAQ: Common Questions About Dependency Failures
How do I know if a service failure is due to dependencies?
Check service status: systemctl status service-name. Look for "Dependency" errors in the output. Check failed dependencies: systemctl list-dependencies service-name --state=failed.
What should I do immediately when dependencies fail?
Immediately check failed dependencies: systemctl --failed. Identify dependency issues: systemctl list-dependencies service-name --state=failed. Start failed dependencies: systemctl start dependency-name. Restart dependent service: systemctl restart service-name.
Can dependency failures cause cascading service failures?
Yes, when a critical dependency fails, all dependent services can fail. This is why monitoring dependencies is essential.
How can Zuzia.app help prevent dependency failures?
Zuzia.app monitors service dependencies continuously, detects dependency failures immediately, sends alerts when dependencies fail, and tracks dependency health over time.