RestedPi

IoT automation middleware for the Raspberry Pi. RestedPi talks to I2C sensors and GPIO expanders, runs automations written in a small boolean-expression language, and exposes everything through a GraphQL API with Prometheus-style metrics.

Features

• Hardware support over I2C:
  • MCP9808 high-accuracy temperature sensor
  • BMP085 pressure/temperature sensor
  • MCP23017 16-port GPIO expander (inputs and outputs)
• Automations: attach a boolean expression to any output and the server recomputes it as state changes (e.g. turn on a fan when a temperature reading crosses a threshold, or switch lights relative to sunrise/sunset).
• GraphQL API with JWT-style token authentication for managing devices, inputs, and outputs at runtime.
• Metrics endpoint exposing current input/output values in Prometheus text format.
• SQLite storage for device configuration and state.

Building

# Host build with mock hardware (the default; no Raspberry Pi required)
cargo build

# Build with real Raspberry Pi hardware support (rppal-based I2C/GPIO)
cargo build --features raspberrypi

# Run the test suite (mock GPIO implementations)
cargo test --features mock-gpio

Running

# Start the server
restedpi server

# Interactive REPL for trying out boolean expressions
restedpi boolean-repl

# Add a user to the config file (prompts for password if not given)
restedpi add-user --username <name> [--password <password>]

Configuration

RestedPi reads a TOML config file from ~/.config/restedpi/config.toml or /etc/restedpi/config.toml (override with --config-file <path>).

# Example config.toml
listen = "0.0.0.0"
port = 3030
i2cbus = 1

# Location used by the "here" value in expressions (sunrise/sunset math)
lat = 49.2
long = -123.1

# Directory containing the SQLite database (rpi.sql3)
db_path = "/var/lib/restedpi"

# File containing the session-signing secret (hex-encoded random bytes).
# If unset, the APP_SECRET environment variable is used instead.
app_secret_path = "/etc/restedpi/secret"

# Optional TLS; provide both to serve HTTPS
tls_key_path = "/etc/restedpi/key.pem"
tls_cert_path = "/etc/restedpi/cert.pem"

Every setting can also be supplied as an environment variable with the RESTEDPI_ prefix, which takes priority over the config file:

• RESTEDPI_PORT=8080
• RESTEDPI_LISTEN=0.0.0.0
• RESTEDPI_I2CBUS=1
• RESTEDPI_LAT=45.5
• RESTEDPI_LONG=-122.6
• RESTEDPI_DB_PATH=/var/lib/restedpi
• RESTEDPI_APP_SECRET_PATH=/etc/restedpi/secret
• RESTEDPI_TLS_KEY_PATH=/etc/restedpi/key.pem
• RESTEDPI_TLS_CERT_PATH=/etc/restedpi/cert.pem

Endpoints

Path	Description
/graphql	GraphQL queries and mutations (POST); GraphQL Playground (GET)
/subscriptions	GraphQL subscriptions over WebSocket
/metrics	Current input/output values in Prometheus text format
/	Single-page web app

Boolean expression language

Automations and the REPL use a small expression language. An expression evaluates to true or false; outputs with an automation script are set to the result whenever state changes.

# Logic
true
a and b or not c
(door_open or window_open) and not alarm_armed

# Comparisons on values: ==, !=, <, <=, >, >=, between
read(greenhouse, degC) > 21.5
read(pressure_sensor, kpa) between 95 and 105

# Approximate equality
plus/minus 0.5, read(greenhouse, degC) == 21

# Time and sun position
hour_of_day(now) between 7 and 10
hour_of_day(now) > hour_of_sunrise(here, now)
week_day(now) < 5

# Arithmetic and interpolation
read(indoor, degC) - read(outdoor, degC) > 5
lerp(1, 0.5, 2) == 1.5

Building blocks:

• read(name, unit) reads an input by name; units are degC, kpa, bool
• hour_of_day(now), minute_of_hour(now), week_day(now), day_of_year(now), month_of_year(now), year(now)
• hour_of_sunrise(here, now), hour_of_sunset(here, now), hours_of_daylight(here, now) — here comes from the configured lat/long, or write an explicit location like 49.2 degN 123.1 degW
• lerp(a, t, b) linearly interpolates between a and b
• Arithmetic: +, -, *, /, parentheses

Try expressions interactively with restedpi boolean-repl.

License

MIT — see LICENSE.