Implement configuration via Pydantic & change project structure

Readme.md

@@ -1,4 +1,3 @@
-
 # Introduction
 
 Simple script utilities to add BME680 sensor readings to Apple Homekit using a Raspberry PI with minimal configuration.
@@ -21,18 +20,29 @@ sudo apt-get install libavahi-compat-libdnssd-dev
 pip3 install -r requirements.txt
 ```
 
-### Sensors
+### Application
 
-The `sensors` directory contains code for operating the bme680 sensor. 
+The `app` directory contains the source code of this application
 
-The sensor values are collected and exposed in HomeKit and as prometheus metrics. 
-The prometheus metrics can be accessed on port `8000`.
+Sensor values are collected and exposed in HomeKit and as prometheus metrics.
+
+By default, metrics can be accessed on port `8000`.
+
+
+
+### Configuration
+
+Before running the program edit the `config.yaml` file and replace at least `persist_file` field.
+
+The program will search for the `config.yaml` file in the current directory but this can be configured to another directory
+by settings the `HOMEKIT_CONFIG` environment variable.
+
+### Running
 
 Run the program once to pair it with your ios. ex:
 
 ```bash
-cd sensors
-python3 main.py 
+python3 -m app.main 
 Setup payload: X-HM://0023K50QET2YB
 Scan this code with your HomeKit app on your iOS device:
 
@@ -40,10 +50,19 @@ Or enter this code in your HomeKit app on your iOS device: 053-86-998
 
 ```
 
+### SystemD Service
+
+Edit `./systemd/bme680-homekit.service` and replace relevant variables such as `WorkingDirectory`, `ExecStart`
+and `User`.
+
+Run `sudo ./systemd/install.sh` to install SystemD service automatically on your system.
+
+Or follow the manual steps.
+
 Copy the systemd service.
 
 ```bash
-sudo cp bme680-homekit.service /etc/systemd/system
+sudo cp ./systemd/bme680-homekit.service /etc/systemd/system
 sudo systemctl status bme680-homekit
 ```
 
@@ -54,6 +73,7 @@ sudo systemctl status bme680-homekit
 ```
 
 Start the service
+
 ```bash
 sudo systemctl start bme680-homekit
 sudo systemctl status bme680-homekit

app/config.py

@@ -0,0 +1,117 @@
+import functools
+import os
+from pathlib import Path
+from typing import Type, Tuple, Any, Dict
+
+import yaml
+from pydantic import BaseModel, Field
+from pydantic.fields import FieldInfo
+from pydantic_settings import BaseSettings, PydanticBaseSettingsSource
+
+config_file_default_location = "config.yaml"
+
+
+class PrometheusSettings(BaseModel):
+    enabled: bool = Field(True, description="Enable prometheus metrics server.")
+    port: int = Field(8000, description="The prometheus metrics server port.")
+
+
+class Bme680Settings(BaseModel):
+    enabled: bool = Field(True, description="If the sensor should be enabled on not.")
+    address: int = Field(
+        0x76, description="The I2C address of the sensor. Defaults to primary"
+    )
+    name: str = Field("Climate Sensor", description="The name of the sensor.")
+
+
+class BridgeSettings(BaseModel):
+    display_name: str = Field(
+        "Bridge", description="The display name of the HAP bridge."
+    )
+    bme680: Bme680Settings = Field(
+        Bme680Settings(), description="Settings for the BME680 module."
+    )
+
+
+class HomekitAccessoryProtocolSettings(BaseModel):
+    port: int = Field(
+        51826, description="The port of the homekit accessory protocol server."
+    )
+    persist_file: str = Field(
+        ...,
+        description="The persistence file which holds the homekit accessory protocol server's state.",
+    )
+    bridge: BridgeSettings = Field(
+        BridgeSettings(), description="The HAP's default bridge settings."
+    )
+
+
+class YamlConfigSettingsSource(PydanticBaseSettingsSource):
+    """
+    A simple settings source class that loads variables from a YAML file
+    at the project's root.
+
+    Here we happen to choose to use the `env_file_encoding` from Config
+    when reading `config.yaml`
+    """
+
+    @functools.lru_cache
+    def read_file_content(self):
+        encoding = self.config.get("env_file_encoding")
+        return yaml.safe_load(
+            Path(
+                os.getenv("HOMEKIT_CONFIG", default=config_file_default_location)
+            ).read_text(encoding)
+        )
+
+    def get_field_value(
+        self, field: FieldInfo, field_name: str
+    ) -> Tuple[Any, str, bool]:
+        file_content_json = self.read_file_content()
+        field_value = file_content_json.get(field_name)
+        return field_value, field_name, False
+
+    def prepare_field_value(
+        self, field_name: str, field: FieldInfo, value: Any, value_is_complex: bool
+    ) -> Any:
+        return value
+
+    def __call__(self) -> Dict[str, Any]:
+        d: Dict[str, Any] = {}
+
+        for field_name, field in self.settings_cls.model_fields.items():
+            field_value, field_key, value_is_complex = self.get_field_value(
+                field, field_name
+            )
+            field_value = self.prepare_field_value(
+                field_name, field, field_value, value_is_complex
+            )
+            if field_value is not None:
+                d[field_key] = field_value
+
+        return d
+
+
+class Settings(BaseSettings):
+    prometheus: PrometheusSettings = Field(
+        PrometheusSettings(), description="Settings for prometheus."
+    )
+    hap: HomekitAccessoryProtocolSettings = Field(
+        ..., description="Homekit Accessory Protocol server settings."
+    )
+
+    @classmethod
+    def settings_customise_sources(
+        cls,
+        settings_cls: Type[BaseSettings],
+        init_settings: PydanticBaseSettingsSource,
+        env_settings: PydanticBaseSettingsSource,
+        dotenv_settings: PydanticBaseSettingsSource,
+        file_secret_settings: PydanticBaseSettingsSource,
+    ) -> Tuple[PydanticBaseSettingsSource, ...]:
+        return (
+            init_settings,
+            YamlConfigSettingsSource(settings_cls),
+            env_settings,
+            file_secret_settings,
+        )

app/main.py

@@ -0,0 +1,41 @@
+import signal
+
+from prometheus_client import start_http_server
+from pyhap.accessory import Bridge
+from pyhap.accessory_driver import AccessoryDriver
+
+from app.config import Settings
+from app.sensors.bme import Bme680Sensor
+
+
+def get_bridge(accessory_driver: AccessoryDriver, settings: Settings):
+    """
+    Returns a Homekit Bridge.
+
+    Parameters
+    ----------
+    accessory_driver: AccessoryDriver
+        The accessory driver.
+    """
+    bridge = Bridge(accessory_driver, settings.hap.bridge.display_name)
+    if settings.hap.bridge.bme680.enabled:
+        bridge.add_accessory(
+            Bme680Sensor(
+                accessory_driver, settings.hap.bridge.bme680.name, settings=settings
+            )
+        )
+    return bridge
+
+
+if __name__ == "__main__":
+    settings = Settings()
+    # Start prometheus metrics server. Any metrics will be registered automatically.
+    if settings.prometheus.enabled:
+        start_http_server(settings.prometheus.port)
+    # Python HAP
+    driver = AccessoryDriver(
+        port=settings.hap.port, persist_file=settings.hap.persist_file
+    )
+    driver.add_accessory(accessory=get_bridge(driver, settings))
+    signal.signal(signal.SIGTERM, driver.signal_handler)
+    driver.start()

app/sensors/bme.py

@@ -1,21 +1,12 @@
 import logging
 import os
-import signal
 import sys
 
-import bme680
-from prometheus_client import Gauge, start_http_server
-from pyhap.accessory import Accessory, Bridge
-from pyhap.accessory_driver import AccessoryDriver
+from prometheus_client import Gauge
+from pyhap.accessory import Accessory
 from pyhap.const import CATEGORY_SENSOR
 
-
-def fail(message: str):
-    """
-    Fail crashes the program and logs the message.
-    """
-    logging.critical(message)
-    sys.exit(1)
+from app.config import Settings
 
 
 class Bme680Sensor(Accessory):
@@ -23,14 +14,17 @@ class Bme680Sensor(Accessory):
 
     category = CATEGORY_SENSOR  # This is for the icon in the iOS Home app.
 
-    def __init__(self, *args, **kwargs):
+    def __init__(self, driver, display_name, *, aid=None, settings: Settings):
         """Here, we just store a reference to the current temperature characteristic and
         add a method that will be executed every time its value changes.
         """
         # If overriding this method, be sure to call the super's implementation first.
-        super().__init__(*args, **kwargs)
+        super().__init__(driver, display_name, aid=aid)
 
-        self.sensor = bme680.BME680(bme680.I2C_ADDR_PRIMARY)
+        self.settings = settings
+        self.sensor = bme680.BME680(
+            settings.hap.bridge.bme680.address or bme680.I2C_ADDR_PRIMARY
+        )
 
         self.sensor.set_humidity_oversample(bme680.OS_2X)
         self.sensor.set_pressure_oversample(bme680.OS_4X)
@@ -87,28 +81,11 @@ class Bme680Sensor(Accessory):
             self._run()
         except IOError as e:
             # This happens from time to time, best we stop and let systemd restart us.
-            fail(f"Failed due to IOError: {e}")
+            logging.critical("Failed to run BME680.")
+            sys.exit(1)
 
     def stop(self):
         """We override this method to clean up any resources or perform final actions, as
         this is called by the AccessoryDriver when the Accessory is being stopped.
         """
         print("Stopping accessory.")
-
-
-def get_bridge(accessory_driver):
-    bridge = Bridge(accessory_driver, "Bridge")
-    bridge.add_accessory(Bme680Sensor(accessory_driver, "Sensor"))
-    return bridge
-
-
-if __name__ == "__main__":
-    # Prometheus' metrics server
-    start_http_server(8000)
-    # Python HAP
-    driver = AccessoryDriver(
-        port=51826, persist_file="/home/pi/bme680-homekit/sensors/accessory.state"
-    )
-    driver.add_accessory(accessory=get_bridge(driver))
-    signal.signal(signal.SIGTERM, driver.signal_handler)
-    driver.start()

config.yaml

@@ -0,0 +1,12 @@
+prometheus:
+  enabled: yes
+  port: 8000
+hap:
+  port: 51826
+  persist_file: /home/pi/bme680-homekit/sensors/accessory.state
+  bridge:
+    display_name: Bridge
+    bme680:
+      enabled: yes
+      address: 118 # Primary I2C Address
+      name: "Climate Sensor"

requirements.txt

@@ -1,3 +1,4 @@
 bme680==1.1.1
 HAP-python==4.4.0
-prometheus-client==0.14.1
+prometheus-client== 0.19.0
+PyYAML==6.0.1

systemd/bme680-homekit.service

@@ -7,7 +7,7 @@ WorkingDirectory=/home/pi/bme680-homekit/
 Restart=on-failure
 RestartSec=5s
 User=pi
-ExecStart=/usr/bin/python3 /home/pi/bme680-homekit/sensors/main.py
+ExecStart=/usr/bin/python3 -m app.main
 
 [Install]
 WantedBy=multi-user.target

systemd/install.sh

@@ -1,5 +1,5 @@
 # Install the systemd service
-cp bme680-homekit.service /etc/systemd/system
+cp ./systemd/bme680-homekit.service /etc/systemd/system
 systemctl daemon-reload
 systemctl start bme680-homekit
 systemctl enable bme680-homekit