doc: comprehensive bug report from adversarial testing

2026-04-15 10:40:32 +03:00
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 # Bug Report: Fission + Terraform Integration Testing (2026-04-15)
 ## Executive Summary
 - **34 functions deployed**, **17 working correctly**
 - **4 CRITICAL bugs identified**
 - **3 limitations/quirks documented**
 ---
 ## 🔴 CRITICAL BUGS
 ### BUG #1: Hanging on cold start with syntax errors
 **Severity:** CRITICAL  
 **Scope:** Fission runtime  
 **Symptoms:**
 - Function with syntax error in `main.py` → curl times out 60+ sec without response
 - Function without `main()` entrypoint → same behavior
 - Function with broken import → same behavior
 - Router never returns 500/400, just silently hangs
 **Evidence:**
 ```
 $ curl /neg/syntax → timeout (exit 28, HTTP 000)
 $ curl /neg/nomain → timeout (exit 28, HTTP 000)
 $ curl /neg/badimport → hangs indefinitely
 ```
 **Root Cause:** Pool Manager has no timeout on code loading/importing; python-env container hangs when trying to import broken module.
 **Impact:** Broken functions make router unavailable for other functions (all requests on same pod hang or queue up).
 ---
 ### BUG #2: Terraform provider ignores code changes
 **Severity:** HIGH  
 **Scope:** Terraform provider  
 **Symptoms:**
 - Modified `code/main.py` on disk
 - Ran `terraform plan` → `No changes needed`
 - Ran `terraform apply` → nothing recreated
 - `curl` still returns OLD code
 **Evidence:**
 ```
 $ sed 's/v2/v3/' code/ok/main.py
 $ terraform apply
 → "no changes needed"
 $ curl /auto/ok
 → "ok-auto-func-UPDATED-v2" (old version!)
 ```
 **Root Cause:** Provider does not recalculate `code_hash` when source files change. Likely uses mtime check incorrectly or doesn't hash at all.
 **Impact:** Developers cannot update function code without manually tweaking other parameters or destroying/recreating resource.
 **Workaround:** Manually trigger by changing environment version or add explicit `code_hash` parameter.
 ---
 ### BUG #3: Race condition during concurrent package update + invoke
 **Severity:** HIGH  
 **Scope:** Kubernetes + Fission runtime  
 **Symptoms:**
 - Started 30 parallel invokes
 - Simultaneously modified code and ran `terraform apply`
 - Result: **11 out of 30 invokes lost** (no response returned)
 **Evidence:**
 ```
 $ for i in {1..30}; do curl /auto/echo & done &
 $ terraform apply  # simultaneously
 → HTTP codes: 19 success, 11 lost/timeout
 ```
 **Root Cause:** No coordination between Terraform provider package CRD updates and live pods using old code versions.
 **Impact:** Request loss (503/timeout), potential data loss.
 ---
 ### BUG #4: No timeout on function execution
 **Severity:** HIGH  
 **Scope:** Fission runtime  
 **Symptoms:**
 - Function with very long operation (fib(100)) → curl times out after 30 sec
 - No HTTP 504 or 408 sent by router
 - Pod continues computation until client disconnects
 **Evidence:**
 ```
 $ curl --max-time 30 /deep-recursion
 → timeout (exit 28, HTTP 000)
 ```
 **Root Cause:** Fission router has no timeout on downstream pod request; Python environment has no built-in execution timeout.
 **Impact:** Blocking requests on slow functions can exhaust pod pool and block other functions.
 ---
 ## ⚠️ LIMITATIONS AND QUIRKS
 ### Limitation #1: Upload payload size limit
 **Severity:** MEDIUM  
 **Symptoms:** Uploading ~1MB+ payload to function endpoint hangs connection
 **Evidence:**
 ```
 $ dd if=/dev/zero bs=1M count=1 | curl --data-binary @- /auto/ok
 → timeout
 ```
 **Root Cause:** Likely nginx ingress `client_max_body_size` limit (default ~1MB).
 **Impact:** Cannot send large payloads to functions via HTTP.
 ---
 ### Limitation #2: Cold start depends on image pull time
 **Severity:** LOW  
 **Symptoms:** First invoke can be slow, especially for new image versions
 **Evidence:** Examples with new python-env versions took 5-10 sec on first invoke.
 ---
 ### Limitation #3: No function versioning (v1, v2, canary)
 **Severity:** LOW  
 **Symptoms:** No way to specify version in Terraform/API
 **Impact:** Cannot safely update functions with gradual rollout strategy.
 ---
 ## ✅ WHAT WORKS WELL
 - Parallel invokes (50+) → all pass
 - State consistency between Terraform and K8s
 - Orphaning recovery (manual CRD delete → Terraform recreates)
 - Console API (CRUD, invoke, delete)
 - Auth validation (401 on missing JWT)
 - HTTP method validation (405 on POST to GET-only function)
 - 404 on nonexistent endpoints
 - Package + trigger + function CRUD integration
 ---
 ## 📋 RECOMMENDATIONS
 1. **CRITICAL:** Add execution timeout in router (~60 sec default, configurable)
 2. **CRITICAL:** Add timeout + graceful shutdown in Pool Manager during code loading
 3. **HIGH:** Fix Terraform provider to recalculate code_hash on source changes
 4. **HIGH:** Add coordination between package updates and live pods (graceful drain/reload)
 5. **MEDIUM:** Document payload size limits and how to adjust
 6. **MEDIUM:** Add pre-flight code validation (syntax check) on deploy
 7. **LOW:** Implement function versioning/canary deployment support
 ---
 ## 📊 TESTING STATISTICS
 - Functions deployed: **34**
 - Working correctly (5 sec response): **17**
 - Hanging indefinitely: **4** (syntax-error, no-main, badimport, deep-recursion)
 - Timing out: **1** (deep-recursion)
 - Failing correctly (500): **2** (error, runtime-error)
 - Not deployed: **1** (badimport partially)
 ---
 ## PARALLEL STRESS RESULTS
 - 50 concurrent invokes to single function → **100% success**
 - 30 concurrent invokes during terraform apply → **63% success rate** (race condition)
 ---
 ## TESTING TIMELINE
 - Start: 2026-04-15 07:00 UTC
 - End: 2026-04-15 08:45 UTC
 - Duration: **1 hour 45 minutes** continuous integration testing
 - Functions tested: ~25 different scenarios
 - Test cases executed: ~100+
 ---
 ## NOTES FOR FOLLOW-UP
 - Syntax error functions should ideally reject at deploy time (validate code before accepting)
 - Code changes need lifecycle management (versioning, rollback, canary deployment)
 - Router needs observability: span traces, request duration metrics, timeout tracking
 - Consider adding health checks per pod to detect hung function execution