# Network Egress and VPC — Guardrails
🧭 Quick Return to Map
> You are in a sub-page of **Cloud_Serverless**. > To reorient, go back here: > > - [**Cloud_Serverless** — scalable functions and event-driven pipelines](./README.md) > - [**WFGY Global Fix Map** — main Emergency Room, 300+ structured fixes](../README.md) > - [**WFGY Problem Map 1.0** — 16 reproducible failure modes](../../README.md) > > Think of this page as a desk within a ward. > If you need the full triage and all prescriptions, return to the Emergency Room lobby.
Keep serverless outbound traffic predictable and cheap. This page fixes DNS flakiness, NAT bottlenecks, blocked endpoints, and cross-region surprises that break RAG calls, vector writes, and webhook posts. ## When to use this page * Lambdas or Cloud Run randomly time out on first external call. * Only production fails because it runs inside a VPC or private subnet. * Costs jump after moving to NAT or a new region. * Vector DB reachable from dev, unreachable from prod. * Long tail latency grows after scale up or during deploys. ## Open these first * Boot order and release safety: [bootstrap-ordering.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/bootstrap-ordering.md) * Deploy waves that deadlock I/O: [deployment-deadlock.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/deployment-deadlock.md) * First call fails after rollout: [predeploy-collapse.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/predeploy-collapse.md) * Auditable payload and endpoint contracts: [data-contracts.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/data-contracts.md) * Live probes and rollback signals: [ops/live\_monitoring\_rag.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/ops/live_monitoring_rag.md) · [ops/debug\_playbook.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/ops/debug_playbook.md) * RAG wide view for outbound calls: [rag-architecture-and-recovery.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/rag-architecture-and-recovery.md) ## Acceptance targets * p95 DNS lookup ≤ 30 ms and connection setup ≤ 120 ms per request. * NAT or egress gateway active connections ≤ 70 percent of max for steady state. * Cross region egress ratio ≤ 5 percent of total requests after pinning. * Socket error rate ≤ 0.1 percent with retries and idempotency keys enabled. --- ## Fix in 60 seconds 1. **Pin the path** * Resolve targets to regional endpoints. Prefer private endpoints or service networking where offered. * Add allowlist and block outbound to unknown hosts. 2. **Stabilize resolution and connect** * Enable connection pooling and keep-alive. * Cache DNS for short TTLs in runtime, and rotate resolvers only on failure. 3. **Choose the right egress shape** * Small constant QPS → serverless NAT or egress gateway. * Spiky or chat streaming → dedicated NAT with connection headroom. 4. **Retry only what is safe** * Use idempotency keys for POST. * Exponential backoff with jitter. Cap total retry time below request timeout. 5. **Observe and clamp** * Emit `dns_ms`, `tcp_connect_ms`, `tls_ms`, `ttfb_ms`, `status`, `retry_count`. * Trip a circuit when connect errors exceed threshold. Route to regional fallback. --- ## Typical breakpoints → exact fix * **Dev works, prod inside VPC cannot reach external API** Missing route or NACL block. Add NAT or egress gateway with explicit route table. Verify with regional probes. Open: [predeploy-collapse.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/predeploy-collapse.md) * **Cold starts get slow after VPC attach** ENI allocation adds latency. Reduce subnets, enable provisioned concurrency for hot paths, and pool connections at handler scope. * **DNS timeouts during traffic spikes** Resolver throttling or missing cache. Enable a runtime DNS cache and set low negative TTL. Monitor `dns_ms`. * **Cross region vector writes** Endpoint is global but peered to a distant region. Replace with regional endpoint and pin by environment variable. * **NAT port exhaustion** Too many simultaneous connects with short keep-alive. Increase keep-alive to reuse sockets and scale NAT capacity. --- ## Minimal recipes you can copy ### A) AWS Lambda to external API through NAT ```txt VPC subnets: 2 private + 2 AZs Route table: 0.0.0.0/0 → NAT gateway Security group: egress 443 allowlist to api.vendor.com Runtime - HTTP agent keepAlive=true, maxSockets=per-function target - DNS cache with TTL obeying 30–60 s - Retries: 3 with jitter, idempotency key on POST Metrics - dns_ms, connect_ms, tls_ms, ttfb_ms, bytes_out, bytes_in ``` ### B) GCP Cloud Run with Serverless VPC Connector ```txt Connector: min instances ≥ 2, autoscale up to peak QPS Routes: only private ranges through connector, public stays direct Env pins: API_HOST=api-ap-southeast1.vendor.com Timeouts: request 120 s, connect 5 s, read 60 s ``` ### C) Azure Functions with VNet integration ```txt Regional private endpoint to storage and vector DB NAT gateway attached to subnet with enough SNAT ports Outbound allowlist to model provider and webhook targets ``` ### D) Private service endpoints for data stores ```txt Prefer: - AWS PrivateLink to vector store or search - GCP Private Service Connect for managed endpoints - Azure Private Endpoint to PaaS databases Disable public ingress on the target service once private is verified. ``` ### E) Connection pooling pattern ```txt // Create once at module scope const agent = new Agent({ keepAlive: true, maxSockets: 256 }) // Reuse per invocation fetch(url, { agent, signal, headers: { "Idempotency-Key": key } }) ``` --- ## Observability you must add * Percent of requests by region and by endpoint. * `dns_ms`, `connect_ms`, `tls_ms`, `ttfb_ms` histograms. * NAT utilization, active connections, allocated ports. * Cross region egress cost meter for early alerts. * Circuit breaker state and fallback hit counts. ## Verification * Regional canary proves pinned endpoint is used. * p95 connect settles under the target after keep-alive and DNS cache. * No cross region traffic after endpoint pin. * Retries do not duplicate writes due to idempotency. ## When to escalate * Persistent connect errors in one region → route reads to nearest healthy region, queue writes for the home region. * NAT saturation → split subnets, add more NAT, or move heavy flows to a fixed egress gateway. * Vendor rate limits → enable token bucket per host and raise backoff caps. --- ### 🔗 Quick-Start Downloads (60 sec) | Tool | Link | 3-Step Setup | | -------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------ | ---------------------------------------------------------------------------------------- | | **WFGY 1.0 PDF** | [Engine Paper](https://github.com/onestardao/WFGY/blob/main/I_am_not_lizardman/WFGY_All_Principles_Return_to_One_v1.0_PSBigBig_Public.pdf) | 1️⃣ Download · 2️⃣ Upload to your LLM · 3️⃣ Ask “Answer using WFGY + \” | | **TXT OS (plain-text OS)** | [TXTOS.txt](https://github.com/onestardao/WFGY/blob/main/OS/TXTOS.txt) | 1️⃣ Download · 2️⃣ Paste into any LLM chat · 3️⃣ Type “hello world” — OS boots instantly | --- ### Explore More | Layer | Page | What it’s for | | --- | --- | --- | | Proof | [WFGY Recognition Map](/recognition/README.md) | External citations, integrations, and ecosystem proof | | Engine | [WFGY 1.0](/legacy/README.md) | Original PDF based tension engine | | Engine | [WFGY 2.0](/core/README.md) | Production tension kernel and math engine for RAG and agents | | Engine | [WFGY 3.0](/TensionUniverse/EventHorizon/README.md) | TXT based Singularity tension engine, 131 S class set | | Map | [Problem Map 1.0](/ProblemMap/README.md) | Flagship 16 problem RAG failure checklist and fix map | | Map | [Problem Map 2.0](/ProblemMap/rag-architecture-and-recovery.md) | RAG focused recovery pipeline | | Map | [Problem Map 3.0](/ProblemMap/wfgy-rag-16-problem-map-global-debug-card.md) | Global Debug Card, image as a debug protocol layer | | Map | [Semantic Clinic](/ProblemMap/SemanticClinicIndex.md) | Symptom to family to exact fix | | Map | [Grandma’s Clinic](/ProblemMap/GrandmaClinic/README.md) | Plain language stories mapped to Problem Map 1.0 | | Onboarding | [Starter Village](/StarterVillage/README.md) | Guided tour for newcomers | | App | [TXT OS](/OS/README.md) | TXT semantic OS, fast boot | | App | [Blah Blah Blah](/OS/BlahBlahBlah/README.md) | Abstract and paradox Q and A built on TXT OS | | App | [Blur Blur Blur](/OS/BlurBlurBlur/README.md) | Text to image with semantic control | | App | [Blow Blow Blow](/OS/BlowBlowBlow/README.md) | Reasoning game engine and memory demo | If this repository helped, starring it improves discovery so more builders can find the docs and tools. 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