---
name: golang-api-server-820fd306aca8
description: Build HTTP services, REST APIs, and middleware in Go. Use when building Go HTTP servers, REST APIs, or custom middleware.
metadata:
  triggers:
    files:
    - 'cmd/server/*.go'
    - 'internal/adapter/handler/**'
    keywords:
    - http server
    - rest api
    - gin
    - echo
    - middleware
---
# Golang API Server

## **Priority: P0 (CRITICAL)**

## Router & GraphQL Selection

- **Standard Lib (`net/http`)**: Use for simple services or zero-dependency requirements. `http.ServeMux` (Go 1.22+) method-based routing.
- **Echo (`labstack/echo`) / Gin**: Recommended for production REST APIs with middleware, binding, and error handling.
- **GraphQL (`99designs/gqlgen`)**: Standard for schema-first GraphQL services. Handlers/resolvers act as thin transport adapters.

## Implementation Workflow

1. **Choose transport layer** — REST (Echo/Gin/stdlib) or GraphQL (gqlgen).
2. **Thin Handlers & Resolvers** — Handlers and resolvers parse/validate inputs, invoke use-case services, and map to transport models. Zero direct database queries or business rules.
3. **Transport-to-Domain Mapping** — Domain models remain pure; transport models adapt to domain models via dedicated mappers.
4. **Response Nullability & Slice Defaulting** — Default empty slices to `[]` (not `null`) unless the schema explicitly requires null. Avoid unnecessary `nullable` fields in GraphQL response schemas when zero-values suffice.
5. **Add middleware** — Use middleware for cross-cutting concerns (Logging, Recovery, CORS, Auth, Tracing, RequestID).
6. **Enforce pagination limits** — Support `first/after` (GraphQL cursor) or `limit/offset` (REST) with strict max caps to prevent memory exhaustion.
7. **Implement graceful shutdown** — Handle SIGINT/SIGTERM to drain in-flight requests.

See [graceful shutdown example](references/graceful-shutdown.md) and [Echo handler patterns](references/middleware-patterns.md)

## Anti-Patterns

- **No business logic in handlers or resolvers**: parse request, call service, and format response only.
- **No direct DB calls in resolvers**: resolvers must call service interfaces, never execute SQL queries.
- **No nil slices in responses**: return empty slice `[]` rather than `null` in API responses unless distinguishing null from empty.
- **No global router/schema vars**: pass router/handler dependencies explicitly via constructor.
- **No missing shutdown**: handle SIGTERM to drain in-flight requests.

## References

- [Middleware Patterns](references/middleware-patterns.md)
- [Graceful Shutdown](references/graceful-shutdown.md)

---
Source attribution: HoangNguyen0403
Original project: https://github.com/HoangNguyen0403/agent-skills-standard
License: MIT
License information: https://opensource.org/license/mit
Original upstream instructions; downloaded from Mega AI Hub.

## Upstream license notice

MIT License

Copyright (c) 2026 Gabriel Moreira

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.



# Mega AI Hub resource metadata

Creator / publisher: HoangNguyen0403
Original project: https://github.com/HoangNguyen0403/agent-skills-standard
Attribution basis: Upstream repository explicitly recorded in package mirror path

Fields of work: Development & Engineering
Roles: Backend Developer, DevOps / SRE, Full-Stack Developer
Specialties: API, Backend
Tools: Go
Country applicability: Country not specified
Classification basis: Source catalog labels
Instruction SHA-256: a66927bf128e2d422a2078c500267a16ec15421d93ced240b93bd8478017e01a