apd.sensors 2.2.1
APD Sensor package
License: MIT
Keywords: iot

# Advanced Python Development Sensors

This is the data collection package that forms part of the running example
for the book [Advanced Python Development](https://advancedpython.dev).

## Usage

This installs a console script called `sensors` that returns a report on
various aspects of the system. The available sensors are:

* Python version
* IP Addresses
* CPU Usage
* RAM Available
* Battery charging state
* Ambient Temperature
* Ambient Humidity

There are no command-line options, to view the report run `sensors` on the
command line.

## Caveats

The Ambient Temperature and Ambient Humidity sensors are only available on
RaspberryPi hosts and assume that a DHT22 sensor is connected to pin `D20`.

The location and type of the sensor can be controlled by setting a pair of
environment variables: `APD_SENSORS_TEMPERATURE_BOARD` and
`APD_SENSORS_TEMPERATURE_PIN`.

If there is an entry in `/etc/hosts` for the current machine's hostname that
value will be the only result from the IP Addresses sensor.

## Installation

You can install with `pip3 install apd.sensors` under Python 3.7 or higher.

We recommend using pipenv to manage your environment, in which case you would
install using `pipenv --three install apd.sensors` and run the programme using 
`pipenv run sensors`.

## API server

There is an optional API server shipped with apd.sensors. To use this you
should install the `apd.sensors[webapp]` extra. The API can then be started
with the non-production quality wsgiref server using:

    python -m apd.sensors.wsgi.serve

or through Waitress (if installed) using:

    waitress-serve --call apd.sensors.wsgi:set_up_config

Other WSGI servers will also work, you should use set_up_config as a factory
function.

An environment variable is required to use the API server, `APD_SENSORS_API_KEY`
should be set to the API key required to gain access. One can be generated
using:

    python -c "import uuid; print(uuid.uuid4().hex)"

The following endpoints are supported:

* /v/3.0/sensors
* /v/3.0/sensors/sensorid
* /v/3.0/deployment_id

## Historical data

You can install optional functionality to periodically store sensor
values using the `apd.sensors[scheduled]` extra. In this case, 
`sensors --save` will store the recorded data to `sensor_data.sqlite`
in the current working directory.

The database connection can be specified with `--db sqlite:////var/sensors.sqlite`,
for example. It can also be specified with the `APD_SENSORS_DB_URI`
environment variable.

The database must be migrated to contain the correct data first. This can be
done by running `alembic upgrade head` with the following alembic.ini file
in the current working directory.

    [alembic]
    script_location = apd.sensors:alembic
    sqlalchemy.url = sqlite:///sensor_data.sqlite

### Historical data API

An API to extract historical data is also available if installed with `apd.sensors[webapp,scheduled,storedapi]`.

This provides the following three URIs, where start and end are a date/time in ISO format.

* /v/3.0/historical
* /v/3.0/historical/start
* /v/3.0/historical/start/end

## Changes

### 2.2.1 (2020-05-21)

* Unexpected errors from sensors should not cause a 500 error in the v3 API (Matthew Wilkes)

### 2.2 (2020-01-17)

* Add ability to store data points on query (Matthew Wilkes)
* Add v3.0 API to distinguish sensor errors and include historical data (Matthew Wilkes)

### 2.1.1 (2020-01-06)

* Cache DHT sensor connections (Matthew Wilkes)
* Force use of bitbang interface for DHT sensors, to improve reliability on Linux (Matthew Wilkes)

### 2.1.0 (2019-12-09)

* Add optional APD_SENSORS_DEPLOYMENT_ID parameter and v2.1 API which allows
  users to find a unique identifier for a webapp sensor deployment (Matthew Wilkes)

### 2.0.0 (2019-09-08)

* Add `to_json_compatible` and `from_json_compatible` methods to Sensor
  to facilitate better HTTP API (Matthew Wilkes)

* HTTP API is now versioned. The API from 1.3.0 is available at /v/1.0
  and an updated version is at /v/2.0 (Matthew Wilkes)

### 1.3.0 (2019-08-20)

* WSGI HTTP API support added (Matthew Wilkes)

### 1.2.0 (2019-08-05)

* Add external plugin support through `apd.sensors.sensors` entrypoint (Matthew Wilkes)

### 1.1.0 (2019-07-12)

* Add --develop argument (Matthew Wilkes)

### 1.0.1 (2019-06-20)

* Fix broken 1.0.0 release (Matthew Wilkes)

### 1.0.0 (2019-06-20)

* Added initial sensors (Matthew Wilkes)

Copyright (c) 2019 Matthew Wilkes

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of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
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