PASSEDcache / port_conflict

Varnish 7.5 Failed to Bind Port 6081 — Already in Use on AlmaLinux 9

Varnish 7.5 cannot start because another process is already using port 6081. Service is in failed state.

Pattern

PROCESS_CRASH_LOOP

Expected: CONNECTION_REFUSED

Severity

HIGH

Confidence

72%

Remediation

Auto-Heal

Test Results

Metric	Expected	Actual
Pattern Recognition	CONNECTION_REFUSED	PROCESS_CRASH_LOOP
Severity Assessment	HIGH	HIGH
Incident Correlation	N/A	None
Cascade Escalation	N/A	No
Remediation	—	Auto-Heal — Corax resolves autonomously

Scenario Conditions

AlmaLinux 9. Varnish 7.5 configured to listen on port 6081. Another process (PID 5003) already bound to that port. Service start fails with EADDRINUSE.

Injected Error Messages (1)

varnishd EADDRINUSE on AlmaLinux 9 — port 6081 already in use by PID 5003, Varnish 7.5 connection refused on port 6081, service in crash loop, cannot start

Neural Engine Root Cause Analysis

Process crash loop detected — a service is repeatedly crashing and restarting, failing to reach a stable running state. This indicates a persistent issue such as a missing dependency, corrupted configuration, incompatible library version, memory corruption, or an unhandled exception that occurs during startup. In Kubernetes environments, this manifests as CrashLoopBackOff with exponentially increasing restart delays.

Remediation Plan

1. Check service logs immediately before each crash for the error message or stack trace. 2. Look for core dumps in /var/crash/ or the configured core dump location. 3. Verify all dependencies (config files, environment variables, database connectivity) are available. 4. Roll back to the last known working version if the crash started after a deployment. 5. For segfaults, check for library version mismatches or corrupted binaries — reinstall the package.

Improvements Applied

Pattern classified as PROCESS_CRASH_LOOP (expected CONNECTION_REFUSED)

Tested: 2026-04-02Monitors: 1 | Incidents: 1Test ID: cmnhnpqeu03qmlig73j70c0xs