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git.stella-ops.org/docs/operations/runbooks/scanner-timeout.md

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# Runbook: Scanner - Scan Timeout on Complex Images
> **Sprint:** SPRINT_20260117_029_DOCS_runbook_coverage
> **Task:** RUN-002 - Scanner Runbooks
## Metadata
| Field | Value |
|-------|-------|
| **Component** | Scanner |
| **Severity** | Medium |
| **On-call scope** | Platform team |
| **Last updated** | 2026-01-17 |
| **Doctor check** | `check.scanner.timeout-rate` |
---
## Symptoms
- [ ] Scans failing with "timeout exceeded" error
- [ ] Alert `ScannerTimeoutExceeded` firing
- [ ] Metric `scanner_scan_timeout_total` increasing
- [ ] Specific images consistently timing out
- [ ] Error log: "scan operation exceeded timeout of X seconds"
---
## Impact
| Impact Type | Description |
|-------------|-------------|
| **User-facing** | Specific images cannot be scanned; pipeline blocked |
| **Data integrity** | No data loss; scans can be retried with adjusted settings |
| **SLA impact** | Release pipeline delayed for affected images |
---
## Diagnosis
### Quick checks
1. **Check Doctor diagnostics:**
```bash
stella doctor --check check.scanner.timeout-rate
```
2. **Identify failing images:**
```bash
stella scanner jobs list --status timeout --last 1h
```
Look for: Pattern in image types or sizes
3. **Check current timeout settings:**
```bash
stella scanner config get timeouts
```
### Deep diagnosis
1. **Analyze image complexity:**
```bash
stella image inspect <image-ref> --format json | jq '{size, layers: .layers | length, files: .manifest.fileCount}'
```
Problem if: > 50 layers, > 100k files, or > 5GB size
2. **Check scanner worker load:**
```bash
stella scanner workers stats
```
Problem if: All workers at capacity during timeouts
3. **Profile a scan:**
```bash
stella scan image --image <image-ref> --profile --verbose
```
Look for: Which phase is slowest (layer extraction, SBOM generation, vuln matching)
4. **Check for filesystem-heavy images:**
```bash
stella image layers <image-ref> --sort-by file-count
```
Problem if: Single layer with > 50k files (e.g., node_modules)
---
## Resolution
### Immediate mitigation
1. **Increase timeout for specific image:**
```bash
stella scan image --image <image-ref> --timeout 30m
```
2. **Increase global scan timeout:**
```bash
stella scanner config set timeouts.scan 20m
stella scanner workers restart
```
3. **Enable fast mode for initial scan:**
```bash
stella scan image --image <image-ref> --fast-mode
```
### Root cause fix
**If image is too complex:**
1. Enable incremental scanning:
```bash
stella scanner config set scan.incremental_mode true
```
2. Configure layer caching:
```bash
stella scanner config set cache.layer_dedup true
stella scanner config set cache.sbom_cache true
```
**If filesystem is too large:**
1. Enable streaming SBOM generation:
```bash
stella scanner config set sbom.streaming_threshold 500Gi
```
2. Configure file sampling for massive images:
```bash
stella scanner config set sbom.file_sample_max 100000
```
**If vulnerability matching is slow:**
1. Enable parallel matching:
```bash
stella scanner config set vuln.parallel_matching true
stella scanner config set vuln.match_workers 4
```
2. Optimize vulnerability database indexes:
```bash
stella db optimize --component scanner
```
### Verification
```bash
# Retry the previously failing scan
stella scan image --image <image-ref> --timeout 30m
# Monitor scan progress
stella scanner jobs watch <job-id>
# Verify no timeouts in recent scans
stella scanner jobs list --status timeout --last 1h
```
---
## Prevention
- [ ] **Capacity:** Configure appropriate timeouts based on expected image complexity (15m default, 30m for large)
- [ ] **Monitoring:** Alert on timeout rate > 5%
- [ ] **Caching:** Enable layer and SBOM caching for base images
- [ ] **Documentation:** Document image size/complexity limits in user guide
---
## Related Resources
- **Architecture:** `docs/modules/scanner/architecture.md`
- **Related runbooks:** `scanner-oom.md`, `scanner-worker-stuck.md`
- **Dashboard:** Grafana > Stella Ops > Scanner Performance