| name | backend-rust |
| description | Rust gRPC backend patterns, folder structure, module anatomy, and infrastructure wiring for the Anachak multi-tenant SaaS platform. |
Backend Rust Skill
Comprehensive guide for working with the Anachak Rust gRPC backend — a multi-tenant SaaS platform with 11 modules, 32 utility packages, and 90+ RPCs.
Tech Stack
| Layer | Technology | Version |
|---|
| Language | Rust | 2021 edition |
| Transport | gRPC (Tonic) + gRPC-Web | tonic 0.12 |
| Database | PostgreSQL (SQLx) | sqlx 0.8 |
| Proto | Protocol Buffers v3 | Buf CLI v2 |
| Auth | JWT (jsonwebtoken 9) | Access + Refresh |
| Password | Argon2 (argon2 0.5) | PHC-format |
| Payments | Bakong/KHQR (EMV-compliant) | reqwest 0.12 |
| Metrics | Prometheus | prometheus 0.13 |
| WebSocket | tokio-tungstenite 0.24 | Notification broadcast |
| OTP | TOTP (totp-rs 5) | Google Authenticator |
| SMS | Plasgate | Cambodia gateway |
| Email | Resend | HTTP API |
| IDs | ULID (ulid 1) | Sortable, unique |
| Cache | In-memory / Redis (optional) | Feature-gated |
| Observability | tracing + optional OpenTelemetry | Feature-gated otel |
| Hot Reload | cargo watch | cw alias |
Quick Reference
Module Summary
| Module | Files | Key Responsibility |
|---|
| auth | 4 (auth.rs, auth_repo.rs, auth_service.rs, mod.rs) | User accounts, JWT, 2FA, OAuth, sessions, audit |
| company | 4 | Multi-tenant company/branch/member management |
| businesstype | 4 | Industry presets (28 types), pricing tiers |
| billing | 4 | KHQR payments, Bakong polling, streaming |
| coupon | 4 | Coupon creation, validation, redemption tracking |
| role | 4 | RBAC role/permission management |
| subscription | 4 | Plan lifecycle, branch-scoped subscriptions |
| notification | 4 | In-app notification delivery |
| currency | 4 | Multi-currency exchange rates |
| activity | 4 | Audit activity logging |
| admin | 4 | Cross-cutting admin operations |
Entrypoints
| File | Purpose |
|---|
main.rs | Calls internal::startup::run() |
internal/startup/mod.rs | Server bootstrap — env, DB, utils, gRPC server, HTTP, cron, shutdown |
internal/startup/proto.rs | Proto module re-exports & file descriptor set |
internal/startup/events.rs | Event handler registration |
internal/startup/cron_jobs.rs | Cron job scheduling |
internal/startup/http_server.rs | Side-channel HTTP (metrics + WebSocket) |
build.rs | tonic-build proto compilation |
Ports
| Port | Protocol | Purpose |
|---|
50050 | gRPC | Native gRPC + gRPC-Web |
9090 | HTTP | Prometheus metrics |
9091 | WebSocket | Real-time notification broadcast |
Key Patterns
- Repository-Service — Every module:
<module>.rs (types) → <module>_repo.rs (data) → <module>_service.rs (business logic + gRPC)
- Arc-based dependency injection — All shared services wrapped in
Arc<T> and passed explicitly
- gRPC-first — Proto is source of truth; gRPC-Web enabled for browser clients
- Tower layer chain — 7 layers for cross-cutting concerns (recovery, timeout, logging, etc.)
- Tonic interceptor —
AuthInterceptor validates JWT + blacklist, injects user context into metadata
- Graceful shutdown —
ShutdownCoordinator manages ordered teardown of 5 components
- Forward-only SQL migrations — Sequential
.sql files in migrations/
- Event-driven side effects —
EventBus for decoupled reactions to domain events
- Feature flags — PostgreSQL-backed with 60s in-memory refresh
- Unified error handling —
AppError enum → auto-converts to gRPC Status with x-error-code metadata
