Customer API

go-customer-api is a Go REST API for basic customer management.
It uses Gorilla Mux for routing, PostgreSQL for persistence, and Gormigrate to run schema/data migrations automatically on startup.

Features

• CRUD endpoints for customers
• Request validation for customer IDs and payload fields
• Auto-migration and seed data at application startup
• Swagger/OpenAPI documentation

Tech Stack

• Go
• Gorilla Mux
• PostgreSQL
• GORM + Gormigrate
• Swaggo (swagger UI)

Project Structure

controllers/   HTTP handlers
db/            DB connection and runtime migrations
docs/          Generated Swagger files
models/        Data models
routes/        Route registration and middleware
script/        Local DB bootstrap scripts
main.go        Application entrypoint

Prerequisites

• Go 1.24+
• PostgreSQL (local install or Docker)

Environment Variables

Copy .env.example to .env and fill values:

DB_USER=yourusername
DB_PASSWORD=yourpassword
DB_NAME=yourdbname
DB_HOST=localhost
DB_PORT=5432

The app requires all five variables.

Run PostgreSQL With Docker

Use either option:

1. docker compose up -d postgres
2. ./script/create_postgres_db.sh

The script can read values from .env and creates the customers table if missing.

Run the API

go mod tidy
go run main.go

Server URL: http://localhost:8000

On startup, the app:

• Connects to PostgreSQL
• Runs Gormigrate migrations in db/db.go
• Seeds sample customers if they do not already exist

API Endpoints

• GET /api/customers - list all customers
• GET /api/customers/{id} - get one customer
• POST /api/customers - create customer
• PUT /api/customers/{id} - update customer
• DELETE /api/customers/{id} - delete customer

Customer payload:

{
  "first_name": "John",
  "last_name": "Doe",
  "email": "john.doe@example.com"
}

Swagger Docs

After server start:

http://localhost:8000/swagger/index.html

Regenerate docs after changing handler annotations:

swag init

Install swag if needed:

go install github.com/swaggo/swag/cmd/swag@latest