How to Monitor Systemd Service Dependencies

How to Monitor Systemd Service Dependencies

Need to monitor systemd service dependencies on your Linux server? Want to track service dependencies, verify dependency health, and detect dependency failures automatically? This guide shows you how to monitor systemd service dependencies using built-in commands and automated monitoring with Zuzia.app.

For comprehensive service monitoring strategies, see Systemd Services and Dependencies Monitoring Guide. For troubleshooting dependency issues, see Systemd Service Dependency Failures.

Why Monitoring Service Dependencies Matters

Service dependencies determine which services must be running for other services to function correctly. When dependencies fail, dependent services can fail to start or become unstable. Monitoring service dependencies helps you detect dependency failures, prevent cascading service failures, maintain service reliability, and ensure critical services have their required dependencies available.

Method 1: List Service Dependencies

View service dependencies to understand service relationships:

View Service Dependencies

# Show service dependencies
systemctl list-dependencies service-name

# Show reverse dependencies (what depends on this service)
systemctl list-dependencies service-name --reverse

# Show all dependencies including inactive
systemctl list-dependencies service-name --all

# Show dependencies in tree format
systemctl list-dependencies service-name --tree

Check Dependency Status

# Check if required services are running
systemctl list-dependencies service-name --state=active

# View dependency requirements
systemctl show service-name -p Requires

# Check dependency wants
systemctl show service-name -p Wants

# Verify all dependencies are satisfied
systemctl check service-name

Method 2: Monitor Dependency Health

Monitor dependency health to ensure dependencies are available:

Check Dependency Status

# Check all dependencies for a service
for dep in $(systemctl show service-name -p Requires --value); do
  systemctl is-active $dep && echo "$dep: active" || echo "$dep: inactive"
done

# Verify dependency health
systemctl list-dependencies service-name --state=active | grep -v "service-name"

# Check for failed dependencies
systemctl list-dependencies service-name --state=failed

# Monitor dependency status continuously
watch -n 1 'systemctl list-dependencies service-name --state=active'

Track Dependency Changes

# Save current dependency list
systemctl list-dependencies service-name > /tmp/deps-$(date +%Y%m%d).txt

# Compare with previous dependencies
diff /tmp/deps-previous.txt /tmp/deps-current.txt

# Monitor dependency modifications
systemctl show service-name -p Requires,Wants,After

Method 3: Detect Dependency Failures

Detect dependency failures to prevent service issues:

Identify Failed Dependencies

# Check for failed dependencies
systemctl list-dependencies service-name --state=failed

# View dependency errors
systemctl status service-name | grep -A 10 "Dependency"

# Check dependency logs
journalctl -u service-name | grep -i "depend\|require"

# Verify dependency availability
for dep in $(systemctl show service-name -p Requires --value); do
  if ! systemctl is-active $dep > /dev/null; then
    echo "CRITICAL: Dependency $dep is not active"
  fi
done

Monitor Dependency Issues

# Check dependency health for critical services
for service in nginx mysql postgresql; do
  echo "Checking $service dependencies:"
  systemctl list-dependencies $service --state=active
done

# Verify all dependencies are running
systemctl list-dependencies service-name --state=active | wc -l

Method 4: Automated Dependency Monitoring with Zuzia.app

While manual dependency checks work for troubleshooting, production Linux servers require automated dependency monitoring that continuously tracks dependency status, detects failures, and alerts you when dependencies are unavailable.

How Zuzia.app Dependency Monitoring Works

Zuzia.app automatically monitors systemd service dependencies through scheduled command execution. The platform checks dependency status, verifies dependency health, detects dependency failures, and sends alerts when dependencies are unavailable.

Setting Up Dependency Monitoring

1. Add Scheduled Task for Dependency Status

   • Command: systemctl list-dependencies service-name --state=active | wc -l
   • Frequency: Every 10 minutes
   • Alert when: Dependency count changes unexpectedly

2. Configure Critical Dependency Monitoring

   • Command: for dep in $(systemctl show service-name -p Requires --value); do systemctl is-active $dep || echo "FAIL: $dep"; done
   • Frequency: Every 5 minutes
   • Alert when: Critical dependencies not active

3. Set Up Dependency Failure Detection

   • Command: systemctl list-dependencies service-name --state=failed
   • Frequency: Every 10 minutes
   • Alert when: Failed dependencies detected

Custom Dependency Monitoring Commands

Add these commands as scheduled tasks:

# Check service dependencies
systemctl list-dependencies service-name --state=active

# Verify critical dependencies
for dep in $(systemctl show nginx -p Requires --value); do
  systemctl is-active $dep && echo "$dep: OK" || echo "$dep: FAIL"
done

# Monitor dependency health
systemctl list-dependencies service-name --state=active | grep -v "^service-name"

Best Practices

1. Monitor Dependencies Continuously

Use Zuzia.app for continuous dependency monitoring. Set up alerts before dependency issues become critical. Review dependency status regularly.

2. Prioritize Critical Dependencies

Focus monitoring on business-critical services. Set up dedicated monitoring for critical dependencies. Configure immediate alerts for critical dependency failures.

3. Track Dependency Changes

Monitor dependency modifications over time. Compare current dependencies with baselines. Alert on dependency configuration changes.

Troubleshooting

Dependency Not Available

When dependencies are unavailable:

1. Check dependency status: systemctl status dependency-name
2. Start dependency if needed: systemctl start dependency-name
3. Verify dependency health: systemctl is-active dependency-name

Service Fails Due to Dependencies

When services fail due to dependencies:

1. Check dependency status: systemctl list-dependencies service-name --state=failed
2. Review dependency logs: journalctl -u dependency-name
3. Fix dependency issues before starting dependent service

FAQ

Related guides, recipes, and problems

• Related guides

  • Systemd Services and Dependencies Monitoring Guide
  • Server Performance Monitoring Best Practices

• Related recipes

  • Check Service Dependency Health
  • Monitor System Boot Time Performance

• Related problems

  • Systemd Service Dependency Failures
  • Application Deployment Failures