A secure, read-only SQL sandbox API service for running ad-hoc queries against a sample PostgreSQL database. It enforces timeouts, rate limits, and query safety, and returns JSON-formatted results and query plans.

• REST API: POST /api/query, GET /api/health
• Read-only sandbox over PostgreSQL with schema isolation via search_path
• Query validation (whitelist SELECT/WITH/EXPLAIN, forbid dangerous keywords)
• Statement timeout (5s), result row limit (100), query length limit (1000 chars)
• Connection pooling and context timeouts
• EXPLAIN (ANALYZE, FORMAT JSON) parsing for planning/execution metrics
• Nginx reverse proxy with rate limiting, CORS, request logging
• Docker Compose for one-command startup

# From repo root
docker compose up --build
# API on http://localhost:80 via Nginx (or http://localhost:8080 directly to app)

The API reads the following env vars (see docker-compose.yml):

• DB_HOST (default: postgres)
• DB_PORT (default: 5432)
• DB_USER (default: sandbox_ro)
• DB_PASSWORD (default: sandbox_ro)
• DB_NAME (default: goto)
• DB_SSLMODE (default: disable)
• API_PORT (default: 8080)

GET /api/health

Response: { "status": "ok" }

POST /api/query
Content-Type: application/json

{ "query": "SELECT * FROM users LIMIT 10" }

Response:

{
  "execution_time_ms": 12,
  "rows_affected": 10,
  "query_plan": { "Plan": { "Node Type": "Limit", "Total Cost": 123.45 }},
  "plan_metrics": {"planning_time_ms": 0.12, "execution_time_ms": 1.23, "total_cost": 123.45},
  "results": [{"id":1, "name":"User 1", "email":"user1@example.com"}]
}

Errors return with HTTP 4xx/5xx and { "error": "message" }.

# Health
curl -s http://localhost/api/health | jq

# Simple SELECT
curl -s -X POST http://localhost/api/query \
  -H 'Content-Type: application/json' \
  -d '{"query":"SELECT id, name, email FROM users ORDER BY id LIMIT 10"}' | jq

# Join query
curl -s -X POST http://localhost/api/query \
  -H 'Content-Type: application/json' \
  -d '{"query":"SELECT o.id, u.email, o.amount FROM orders o JOIN users u ON u.id=o.user_id ORDER BY o.id LIMIT 10"}' | jq

• Go 1.21+
• Chi router, pq driver, godotenv

Run locally without Docker:

export DB_HOST=localhost DB_USER=sandbox_ro DB_PASSWORD=sandbox_ro DB_NAME=goto DB_SSLMODE=disable
go run ./cmd/api

• Read-only DB user with RLS; no write grants
• Server-side statement_timeout set per transaction
• Query whitelist and blocklist enforced in API
• Nginx rate limiting at 10 req/sec per IP

MIT