Configuration

The engine is configured entirely through environment variables. Copy .env.example to .env to get started.

Environment Variables

Variable	Default	Description
`DB_PATH`	`fpa.db`	Path to the SQLite database file. Use `:memory:` to run entirely in-memory (useful for tests or ephemeral environments).
`PORT`	`8080`	TCP port the HTTP server listens on.

.env.example

DB_PATH=fpa.db
PORT=8080

In-Memory Mode

For tests or CI pipelines where you don't want a file left on disk:

DB_PATH=:memory:

The schema is still applied via auto-migration on startup. Data is lost when the process exits.

HTTP Server Timeouts

Timeouts are hardcoded in main.go and are not currently configurable via environment variables:

Timeout	Value	Purpose
`ReadTimeout`	10s	Maximum time to read the full request
`WriteTimeout`	30s	Maximum time to write the full response (set higher to allow for large variance reports)
`IdleTimeout`	120s	Maximum time to keep an idle keep-alive connection open

Logging

The engine uses Go's log/slog with a JSON handler writing to stdout. All log entries are structured JSON, suitable for ingestion by log aggregators like Loki, Datadog, or CloudWatch.

Example log lines:

{"time":"2026-03-21T08:16:00Z","level":"INFO","msg":"server starting","port":"8080","db":"fpa.db"}
{"time":"2026-03-21T08:16:05Z","level":"ERROR","msg":"migration failed","error":"..."}

Log level is not currently configurable — the logger runs at INFO.

Deployment

Because the engine compiles to a single binary with no runtime dependencies (SQLite is a pure-Go implementation), deployment is straightforward:

# Build
go build -o fpa-engine ./main.go
 
# Run
DB_PATH=/data/fpa.db PORT=8080 ./fpa-engine

It can be containerised, run as a systemd service, or deployed to any platform that can run a Go binary. No Node, Python, or system SQLite library is required.