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PASSEDserver / systemd_service_dependency_loop
systemd Service Dependency Loop
A misconfigured systemd unit file creates a circular dependency between three services, causing them to enter a restart loop. Each service depends on another in the cycle, and systemd cannot satisfy all dependencies simultaneously.
Pattern
PROCESS_CRASH_LOOP
Severity
CRITICAL
Confidence
92%
Remediation
Auto-Heal
Test Results
| Metric | Expected | Actual | Result |
|---|---|---|---|
| Pattern Recognition | PROCESS_CRASH_LOOP | PROCESS_CRASH_LOOP | |
| Severity Assessment | CRITICAL | CRITICAL | |
| Incident Correlation | Yes | 6 linked | |
| Cascade Escalation | N/A | No | |
| Remediation | — | Auto-Heal — Corax resolves autonomously |
Scenario Conditions
RHEL 9 application server. Service A requires Service B (After=B.service). Service B requires Service C (After=C.service). Service C requires Service A (After=A.service). All three services in restart loop. Systemd rate-limiting kicks in after 5 restarts in 10 seconds.
Injected Error Messages (1)
systemd service dependency loop on rhel-app-01 — services app-frontend.service, app-backend.service, and app-cache.service in circular dependency restart loop, systemd: start request repeated too quickly for app-frontend.service, restart loop detected with 5 restarts in 10 seconds, all three services failing to reach active state, rate limiting applied
Neural Engine Root Cause Analysis
The application server is experiencing a systemd service dependency loop where app-frontend.service, app-backend.service, and app-cache.service are circularly dependent on each other. When one service fails and attempts to restart, it triggers cascading restart attempts of the dependent services, creating an infinite loop. Systemd has applied rate limiting after detecting 5 restarts in 10 seconds, preventing any of the services from reaching an active state and making the application completely unavailable.
Remediation Plan
1. Stop all three services involved in the dependency loop (app-frontend, app-backend, app-cache) to break the cycle. 2. Analyze service configuration files to identify and fix the circular dependency relationships. 3. Start services in proper dependency order (typically cache first, then backend, then frontend). 4. Verify all services reach active state and application responds on port 8080. 5. Monitor for stability over next 10 minutes to ensure loop doesn't recur.
Tested: 2026-03-30Monitors: 1 | Incidents: 1Test ID: cmncjyqk405s1obqez2w3qhzs