Charon/docs/plans/current_spec.md

CrowdSec Handler Injection Analysis & Fix Plan

Date: December 15, 2025 Agent: Planning Status: ✅ ANALYSIS COMPLETE - Root Cause Identified - Deployment Issue

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Executive Summary

CrowdSec handler injection code is 100% CORRECT - the issue is deployment configuration.

The Real Problem

The container is missing CERBERUS_SECURITY_CERBERUS_ENABLED=true which causes computeEffectiveFlags() to force crowdsecEnabled=false even though CHARON_SECURITY_CROWDSEC_MODE=local is set.

Evidence

✅ Code is Correct:

• CrowdSec app config generated properly (config.go#L62-L72)
• Handler injection logic working (config.go#L282-L287)
• All unit tests passing (TestBuildCrowdSecHandler_, TestGenerateConfig_CrowdSec)

❌ Deployment is Broken:

• CERBERUS_SECURITY_CERBERUS_ENABLED NOT in container environment
• computeEffectiveFlags() forces all security to disabled when Cerberus master switch is off
• Result: apps.crowdsec NOT generated, handler NOT injected

Container Evidence

$ docker exec charon env | grep CERBERUS
(no output)  # ❌ Missing

$ curl http://localhost:2019/config/apps | jq 'keys'
["http"]  # ❌ No "crowdsec" app

$ curl http://localhost:8080/api/v1/security/config | jq '.crowdsec_mode'
null  # ❌ Not configured

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Root Cause Analysis

The Cerberus Master Switch Problem

File: backend/internal/caddy/manager.go

// ACL, WAF, RateLimit and CrowdSec should only be considered enabled if Cerberus is enabled.
if !cerbEnabled {
    aclEnabled = false
    wafEnabled = false
    rateLimitEnabled = false
    crowdsecEnabled = false  // ← FORCED TO FALSE
}

The Flow:

1. Environment Loading (config.go#L59):

   CerberusEnabled: getEnvAny("false", "CERBERUS_SECURITY_CERBERUS_ENABLED",
                              "CHARON_SECURITY_CERBERUS_ENABLED",
                              "CPM_SECURITY_CERBERUS_ENABLED") == "true",
   

   • Checks for env var in priority order
   • Container has NONE of these variables
   • Result: cerbEnabled = false

2. Flag Computation (manager.go#L417):

   crowdsecEnabled = m.securityCfg.CrowdSecMode == "local"
   

   • CHARON_SECURITY_CROWDSEC_MODE=local IS in container
   • Result: crowdsecEnabled = true (temporarily)

3. Master Switch Override (manager.go#L491):

   if !cerbEnabled {
       crowdsecEnabled = false  // ← Forced to false
   }
   

   • Because cerbEnabled = false
   • Result: crowdsecEnabled = false (final)

4. Config Generation (config.go#L62):

   if crowdsecEnabled {
       config.Apps.CrowdSec = &CrowdSecApp{...}  // ← SKIPPED
   }
   

   • Because crowdsecEnabled = false
   • Result: No CrowdSec app in config

5. Handler Injection (config.go#L285):

   if csH, err := buildCrowdSecHandler(&host, secCfg, crowdsecEnabled); err == nil && csH != nil {
       securityHandlers = append(securityHandlers, csH)  // ← SKIPPED
   }
   

   • buildCrowdSecHandler returns nil when crowdsecEnabled = false
   • Result: No handler in routes

The docker-compose.override.yml Mystery

File: docker-compose.override.yml

environment:
  - CERBERUS_SECURITY_CERBERUS_ENABLED=true  # ← IN FILE
  - CHARON_SECURITY_CROWDSEC_MODE=local

But container inspection shows it's NOT reaching the container:

$ docker exec charon env | grep CERBERUS_SECURITY_CERBERUS_ENABLED
(no output)  # ❌ Variable missing

Possible Causes:

1. Container started without -f docker-compose.override.yml
2. Cached container image has old environment
3. Override file syntax error (YAML indentation)
4. Container restart didn't pick up new environment

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The Fix

Problem Statement

Code is 100% correct. The issue is deployment configuration - the environment variable is not reaching the container.

Solution: Ensure Environment Variable Reaches Container

Option 1: Restart with Correct Compose File (IMMEDIATE - 2 minutes)

cd /projects/Charon

# Stop container
docker compose -f docker-compose.override.yml down

# Rebuild to ensure clean state
docker build -t charon:local .

# Start with override file explicitly
docker compose -f docker-compose.override.yml up -d

# Verify environment
docker exec charon env | grep CERBERUS_SECURITY_CERBERUS_ENABLED
# Should output: CERBERUS_SECURITY_CERBERUS_ENABLED=true

Option 2: Manually Set Environment (WORKAROUND - 1 minute)

# Stop container
docker stop charon

# Start with environment variable
docker start charon -e CERBERUS_SECURITY_CERBERUS_ENABLED=true

# OR restart the container completely
docker rm charon
docker run -d --name charon \
  -e CERBERUS_SECURITY_CERBERUS_ENABLED=true \
  -e CHARON_SECURITY_CROWDSEC_MODE=local \
  # ... other flags from docker-compose.override.yml
  charon:local

Option 3: Fix Code Logic (OPTIONAL - 30 minutes)

Allow CrowdSec to operate independently of Cerberus master switch.

File: backend/internal/caddy/manager.go

Current Code:

// ACL, WAF, RateLimit and CrowdSec should only be considered enabled if Cerberus is enabled.
if !cerbEnabled {
    aclEnabled = false
    wafEnabled = false
    rateLimitEnabled = false
    crowdsecEnabled = false  // ← Forces CrowdSec off
}

Proposed Change:

// ACL, WAF, and RateLimit are Cerberus-specific features.
// CrowdSec can operate independently for defense-in-depth.
if !cerbEnabled {
    aclEnabled = false
    wafEnabled = false
    rateLimitEnabled = false
    // crowdsecEnabled: allow independent operation
}

Conservative Alternative (add warning):

if !cerbEnabled {
    // Store original crowdsec intent
    wantsCrowdSec := crowdsecEnabled

    aclEnabled = false
    wafEnabled = false
    rateLimitEnabled = false
    crowdsecEnabled = false

    // Log warning if user tried to enable CrowdSec without Cerberus
    if wantsCrowdSec {
        logger.Log().Warn("CrowdSec requires Cerberus master switch. Set CERBERUS_SECURITY_CERBERUS_ENABLED=true")
    }
}

---

Verification Steps

After applying fix (Option 1 recommended), verify in this order:

1. Environment Check

docker exec charon env | grep -E "(CERBERUS|CHARON)_SECURITY"

Expected Output:

CERBERUS_SECURITY_CERBERUS_ENABLED=true  ← MUST BE PRESENT
CHARON_SECURITY_CROWDSEC_MODE=local
CHARON_SECURITY_CROWDSEC_API_URL=http://localhost:8080
CHARON_SECURITY_CROWDSEC_API_KEY=charonbouncerkey2024

2. Caddy App Check

curl -s http://localhost:2019/config/apps/crowdsec | jq .

Expected Output:

{
  "api_key": "charonbouncerkey2024",
  "api_url": "http://localhost:8080",
  "enable_streaming": true,
  "ticker_interval": "60s"
}

3. Route Handler Check

curl -s http://localhost:2019/config/apps/http/servers/charon_server/routes | \
  jq '.[0].handle[] | select(.handler == "crowdsec")'

Expected Output:

{
  "handler": "crowdsec"
}

4. Database Check

curl -s http://localhost:8080/api/v1/security/config | jq '{enabled, crowdsec_mode}'

Expected Output (if Cerberus enabled via DB):

{
  "enabled": true,
  "crowdsec_mode": "local"
}

5. Functional Test

# Add test decision
docker exec charon cscli decisions add --ip 192.0.2.1 --duration 1h --reason "test block"

# Simulate blocked request
curl -H "X-Forwarded-For: 192.0.2.1" http://localhost/

# Expected: 403 Forbidden

---

Test Coverage Validation

All existing tests PASS - no code changes needed:

Unit Tests (Handler Building)

• ✅ TestBuildCrowdSecHandler_Disabled - Returns nil when disabled
• ✅ TestBuildCrowdSecHandler_EnabledWithoutConfig - Returns minimal handler
• ✅ TestBuildCrowdSecHandler_EnabledWithCustomAPIURL - Custom API URL works
• ✅ TestBuildCrowdSecHandler_JSONFormat - Valid JSON structure
• ✅ TestBuildCrowdSecHandler_WithHost - Per-host configuration

Integration Tests (Config Generation)

• ✅ TestGenerateConfig_CrowdSecHandlerFromSecCfg - Handler in routes when enabled
• ✅ App-level config correct (api_url, api_key, streaming)
• ✅ Handler is minimal (no inline config)
• ✅ Trusted proxies configured at server level (NOT app level)

Manager Tests (Runtime Flags)

• ✅ TestComputeEffectiveFlags_DB_CrowdSecLocal - Returns true when mode=local
• ✅ TestComputeEffectiveFlags_DB_CrowdSecExternal - Returns false when not local
• ✅ TestManager_ApplyConfig_RuntimeFlags - Handler appears when enabled

Note: The tests use crowdsecEnabled=true parameter directly, bypassing the Cerberus master switch check. This is correct test isolation.

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Conclusion

Research Complete ✅

The CrowdSec handler injection code is 100% correct and working as designed. All handler building, route injection, and configuration generation logic is properly implemented and tested.

Root Cause Identified ✅

The issue is a deployment configuration problem, not a code problem:

1. Container missing CERBERUS_SECURITY_CERBERUS_ENABLED=true environment variable
2. computeEffectiveFlags() forces all security features off when Cerberus master switch is disabled
3. Result: crowdsecEnabled=false → No app config → No handler injection

Implementation Path Clear ✅

Option 1 (Recommended): Fix deployment by ensuring environment variable reaches container

• Time: 2 minutes
• Risk: None (just fixing misconfiguration)
• Impact: Immediate - CrowdSec will work on next restart

Option 2 (Optional): Decouple CrowdSec from Cerberus master switch

• Time: 30 minutes (code + tests)
• Risk: Low (architecture change)
• Impact: Allows CrowdSec to operate independently

Code Quality Validation ✅

• All unit tests passing
• Integration tests passing
• Handler order correct (Security Decisions → CrowdSec → WAF → Rate Limit → ACL → Reverse Proxy)
• App-level config matches plugin docs
• Trusted proxies configured at server level

Documentation Complete ✅

This specification provides:

• Complete root cause analysis with evidence
• Exact line-by-line code flow explanation
• Multiple fix options with tradeoffs
• Comprehensive verification steps
• Test coverage validation

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Status: ✅ READY FOR IMPLEMENTATION Next Step: Apply fix (Option 1 recommended) Owner: DevOps / Infrastructure ETA: 2 minutes for deployment fix, or 30 minutes for code enhancement