All pods run in namespace crs. Use when pods in the crs namespace are in CrashLoopBackOff, OOMKilled, or restarting, multiple services restart simultaneously (cascade failure), or redis is unresponsive or showing AOF warnings.
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All pods run in namespace crs. Use when pods in the crs namespace are in CrashLoopBackOff, OOMKilled, or restarting, multiple services restart simultaneously (cascade failure), or redis is unresponsive or showing AOF warnings.
risk
unknown
source
community
Debug Buttercup
When to Use
Pods in the crs namespace are in CrashLoopBackOff, OOMKilled, or restarting
Always start with triage. Run these three commands first:
# 1. Pod status - look for restarts, CrashLoopBackOff, OOMKilled
kubectl get pods -n crs -o wide
# 2. Events - the timeline of what went wrong
kubectl get events -n crs --sort-by='.lastTimestamp'# 3. Warnings only - filter the noise
kubectl get events -n crs --field-selector type=Warning --sort-by='.lastTimestamp'
Then narrow down:
# Why did a specific pod restart? Check Last State Reason (OOMKilled, Error, Completed)
kubectl describe pod -n crs <pod-name> | grep -A8 'Last State:'# Check actual resource limits vs intended
kubectl get pod -n crs <pod-name> -o jsonpath='{.spec.containers[0].resources}'# Crashed container's logs (--previous = the container that died)
kubectl logs -n crs <pod-name> --previous --tail=200
# Current logs
kubectl logs -n crs <pod-name> --tail=200
Historical vs Ongoing Issues
High restart counts don't necessarily mean an issue is ongoing -- restarts accumulate over a pod's lifetime. Always distinguish:
--tail shows the end of the log buffer, which may contain old messages. Use --since=300s to confirm issues are actively happening now.
--timestamps on log output helps correlate events across services.
Check Last State timestamps in describe pod to see when the most recent crash actually occurred.
Cascade Detection
When many pods restart around the same time, check for a shared-dependency failure before investigating individual pods. The most common cascade: Redis goes down -> every service gets ConnectionError/ConnectionRefusedError -> mass restarts. Look for the same error across multiple --previous logs -- if they all say redis.exceptions.ConnectionError, debug Redis, not the individual services.
Log Analysis
# All replicas of a service at once
kubectl logs -n crs -l app=fuzzer-bot --tail=100 --prefix
# Stream live
kubectl logs -n crs -l app.kubernetes.io/name=redis -f
# Collect all logs to disk (existing script)
bash deployment/collect-logs.sh
Resource Pressure
# Per-pod CPU/memory
kubectl top pods -n crs
# Node-level
kubectl top nodes
# Node conditions (disk pressure, memory pressure, PID pressure)
kubectl describe node <node> | grep -A5 Conditions
# Disk usage inside a pod
kubectl exec -n crs <pod> -- df -h
# What's eating disk
kubectl exec -n crs <pod> -- sh -c 'du -sh /corpus/* 2>/dev/null'
kubectl exec -n crs <pod> -- sh -c 'du -sh /scratch/* 2>/dev/null'
Redis Debugging
Redis is the backbone. When it goes down, everything cascades.
# Redis pod status
kubectl get pods -n crs -l app.kubernetes.io/name=redis
# Redis logs (AOF warnings, OOM, connection issues)
kubectl logs -n crs -l app.kubernetes.io/name=redis --tail=200
# Connect to Redis CLI
kubectl exec -n crs <redis-pod> -- redis-cli
# Inside redis-cli: key diagnostics
INFO memory # used_memory_human, maxmemory
INFO persistence # aof_enabled, aof_last_bgrewrite_status, aof_delayed_fsync
INFO clients # connected_clients, blocked_clients
INFO stats # total_connections_received, rejected_connections
CLIENT LIST # see who's connected
DBSIZE # total keys# AOF configuration
CONFIG GET appendonly # is AOF enabled?
CONFIG GET appendfsync # fsync policy: everysec, always, or no# What is /data mounted on? (disk vs tmpfs matters for AOF performance)
kubectl exec -n crs <redis-pod> -- mount | grep /data
kubectl exec -n crs <redis-pod> -- du -sh /data/
Queue Inspection
Buttercup uses Redis streams with consumer groups. Queue names:
If a pod is restart-looping, the health check file is likely going stale because the main process is blocked (e.g. waiting on Redis, stuck on I/O).
Telemetry (OpenTelemetry / Signoz)
All services export traces and metrics via OpenTelemetry. If Signoz is deployed (global.signoz.deployed: true), use its UI for distributed tracing across services.
# Check if OTEL is configured
kubectl exec -n crs <pod> -- env | grep OTEL
# Verify Signoz pods are running (if deployed)
kubectl get pods -n platform -l app.kubernetes.io/name=signoz
Traces are especially useful for diagnosing slow task processing, identifying which service in a pipeline is the bottleneck, and correlating events across the scheduler -> build-bot -> fuzzer-bot chain.
Volume and Storage
# PVC status
kubectl get pvc -n crs
# Check if corpus tmpfs is mounted, its size, and backing type
kubectl exec -n crs <pod> -- mount | grep corpus_tmpfs
kubectl exec -n crs <pod> -- df -h /corpus_tmpfs 2>/dev/null
# Check if CORPUS_TMPFS_PATH is set
kubectl exec -n crs <pod> -- env | grep CORPUS
# Full disk layout - what's on real disk vs tmpfs
kubectl exec -n crs <pod> -- df -h
CORPUS_TMPFS_PATH is set when global.volumes.corpusTmpfs.enabled: true. This affects fuzzer-bot, coverage-bot, seed-gen, and merger-bot.
Deployment Config Verification
When behavior doesn't match expectations, verify Helm values actually took effect:
# Check a pod's actual resource limits
kubectl get pod -n crs <pod-name> -o jsonpath='{.spec.containers[0].resources}'# Check a pod's actual volume definitions
kubectl get pod -n crs <pod-name> -o jsonpath='{.spec.volumes}'
Helm values template typos (e.g. wrong key names) silently fall back to chart defaults. If deployed resources don't match the values template, check for key name mismatches.
Service-Specific Debugging
For detailed per-service symptoms, root causes, and fixes, see references/failure-patterns.md.
