REST API Setup — App Developers¶

Use SLayer from any language via HTTP. No Python needed in your application — just start the server and call the API.

Install and start¶

uv tool install motley-slayer
slayer serve

For databases other than SQLite, add the driver extra (see full list):

uv tool install 'motley-slayer[postgres]'

The API runs at http://localhost:5143. An MCP SSE endpoint is also available at /mcp/sse.

Connect a database¶

Create a datasource config file:

# slayer_data/datasources/my_pg.yaml
name: my_pg
type: postgres
host: localhost
port: 5432
database: myapp
username: analyst
password: ${DB_PASSWORD}

The recommended one-shot is to start the server with --ingest-on-startup, which walks every configured datasource on boot and runs idempotent auto-ingestion before the port opens:

slayer serve --ingest-on-startup

Or ingest manually (re-runnable without restarting the server):

slayer ingest --datasource my_pg

Or do everything via the API:

# Create datasource
curl -X POST http://localhost:5143/datasources \
  -H "Content-Type: application/json" \
  -d '{"name": "my_pg", "type": "postgres", "host": "localhost", "database": "myapp", "username": "analyst", "password": "secret"}'

# Ingest models
curl -X POST http://localhost:5143/ingest \
  -H "Content-Type: application/json" \
  -d '{"datasource": "my_pg"}'

Query¶

# Count orders by status
curl -X POST http://localhost:5143/query \
  -H "Content-Type: application/json" \
  -d '{
    "source_model": "orders",
    "measures": ["*:count"],
    "dimensions": ["status"]
  }'

Response:

{
  "data": [
    {"orders.status": "completed", "orders._count": 42},
    {"orders.status": "pending", "orders._count": 15}
  ],
  "columns": ["orders.status", "orders._count"],
  "row_count": 2
}

More examples¶

# Monthly revenue with date range
curl -X POST http://localhost:5143/query \
  -H "Content-Type: application/json" \
  -d '{
    "source_model": "orders",
    "measures": ["revenue:sum"],
    "time_dimensions": [{"dimension": "created_at", "granularity": "month", "date_range": ["2024-01-01", "2024-12-31"]}]
  }'

# Top 5 customers
curl -X POST http://localhost:5143/query \
  -H "Content-Type: application/json" \
  -d '{
    "source_model": "orders",
    "measures": ["revenue:sum"],
    "dimensions": ["customers.name"],
    "order": [{"column": "revenue:sum", "direction": "desc"}],
    "limit": 5
  }'

# List models
curl http://localhost:5143/models

# Get model details
curl http://localhost:5143/models/orders

Verify it works¶

# Health check
curl http://localhost:5143/health
# {"status": "ok"}

# List models (should return your ingested models)
curl http://localhost:5143/models

If /models returns an empty list, restart with slayer serve --ingest-on-startup or run slayer ingest --datasource my_pg.

Using from other languages¶

SLayer is just HTTP + JSON — use any HTTP client:

JavaScript:

const res = await fetch("http://localhost:5143/query", {
  method: "POST",
  headers: {"Content-Type": "application/json"},
  body: JSON.stringify({
    source_model: "orders",
    measures: ["*:count"],
    dimensions: ["status"],
  }),
});
const {data} = await res.json();

Go:

body := `{"source_model": "orders", "measures": ["*:count"]}`
resp, _ := http.Post("http://localhost:5143/query", "application/json", strings.NewReader(body))

See the REST API Reference for all endpoints.