prometheus-android-exporter/README.md

prometheus-android-exporter

Prometheus exporter for Android phones. It is not yet available on Google Play. Prometheus Android Exporter is implemented in Kotlin in Jetpack Compose. Apart from simply exporting available metrics on the default HTTP port 10101, it can also traverse NAT by connecting to the PushProx proxy. It also supports scraping metrics locally and storing them in memory while offline and exporting them later while online using the Prometheus remote write protocol.

Operation

This application can operate in three modes (simultaneously):

• as a Prometheus exporter by exposing metrics on HTTP port 10101
• as a PushProx proxy client, to traverse NAT and other network barriers while still following the pull model
• as a batch exporter, which can store metrics to memory while device is offline and later export them to Prometheus via remote write protocol while device becomes online

Application is configurable either via its UI or via YAML configuration file.

UI configuration

Each tab on the homepage of the application corresponds to one application mode. For example, to configure PushProx client to traverse NAT while still following the pull model, I can open the application, go to tab "PushProx", fill out FQDN - fully qualified domain name and PushProx URL, switch this mode on by tapping on the switch, and tap "Start".

File configuration

Client application is configurable via a configuration file. Place such file on your android device at a following path:

data/user/0/com.birdthedeveloper.prometheus.android.exporter/files/

The name of such configuration file can be either config.yaml or config.yml

Configurable fields are described in ./config_file_structure.yaml, most fields are optional.

After configuring the application via configuration file, one has to still start the exporter manually by opening the app and hitting "Start" button.

Repository contents

• .circleci contains configuration file for continuous integration pipeline, that runs on the CircleCI platform. This CI pipeline runs linter, unit tests, and builds the project for each commit.
• Folder client contains Jetpack Compose Android Prometheus Exporter written in Kotlin. This is a Android Studio project. Inside the Android project, inside the java/com/birdthedeveloper/prometheus/android/exporter folder are the following Kotlin files:
  • compose/Configuration.kt: parser of the YAML file.
  • compose/HomeActivity.kt: homepage UI, all three tabs are defined here.
  • compose/MainActivity.kt: main activity, application navigation is defined here.
  • compose/PromViewModel.kt: View model, global state management of the application.
  • compose/SettingsActivity.kt: The settings page with attribution and license notice.
  • ui/*: these files were generated with the project.
  • worker/AndroidCustomExporter.kt: here is implemented a custom collector for metrics along with all the functions that collect various hardware and software metrics from the device.
  • worker/ExponentialBackoff.kt: here is implemented a simple exponential backoff strategy, used when sending HTTP requests using either batch exporter or PushProx client mode.
  • worker/MetricsEngine.kt: functions for accessing hardware sensors and other metrics.
  • worker/PrometheusServer.kt: implementation of the Prometheus exporter - HTTP server via Ktor.
  • worker/PromWorker.kt: implementation of the Android WorkManager worker. This worker consumes configuration from either
  • worker/PushProxClient.kt: in the file is implemented the PushProx client mode
  • worker/RemoteWriteSender.kt: in this file is implemented the batch exporter mode.
  • worker/RemoteWriteSenderMemStorage.kt: memory store for metrics when the device is offline. Used by the batch exporter.
  • worker/RemoteWriteSenderStorage.kt: abstract class that serves as a contract for the batch exporter storage. If you want to add persistent storage to metrics, extend this class.
  • worker/Util.kt: this file contains utility functions used accross the whole app, such as function to determine whether a network is available.
• Folder server contains ansible playbook for simple deployment of prometheus monitoring stack on a virtual private server, that is deployment of prometheus database itself, grafana monitoring dashboard and pushprox, a prometheus proxy used to traverse NAT while still following the pull model.
• Folder local contains simple docker-compose.yaml files to spin up prometheus database on localhost quickly for testing purposes with desired configuration.
• Configuration options for the YAML file are described in config_file_structure.yaml.

Some helpful information for development

ADB port forwarding

ADB port forwarding is usefull when running the client application on an android emulator and prometheus database on the host ADB port forwarding allows to map specific host's port to emulator's port Syntax is as follows (for port 8080)

$ adb forward tcp:8080 tcp:8080

Server configuration for PushProx proxy

To configure new VPS linux server for Prometheus with PushProx proxy, you can use the provided ansible playbook. This playbook is meant to be use against freshly provisioned RedHat Linux or Rocky Linux or Alma Linux server.

To run locally, just use the included docker-compose.yaml file as a template.

TL;DR

$ cd ./server

# edit ansible_inventory to add your own linux server

# To apply ansible playbook
$ ansible-playbook ansible_playbook.yaml

# To only apply changed configuration (for example change prometheus.yaml file)
$ ansible-playbook ansible_playbook.yaml --tags config

List of exported metrics:

Android hardware sensors

android_sensor_heading_degrees - Data from the Android heading sensor android_sensor_proximity_metres - Data from the proximity sensor android_sensor_heading_accuracy_degrees - Data from Android the heading sensor android_sensor_hinge_angle_degrees - How much is the hinge opened android_sensor_accelerometer{axis} - Data from the accelerometer android_sensor_magnetic_field_tesla{axis} - Data from the magnetic field sensor in base units android_sensor_gravity_acceleration{axis} - Data from gravity acceleration sensor, in m/s^2 units android_sensor_linear_acceleration{axis} - Data from the Android linear acceleration sensor in m/s^2 units. android_sensor_pressure_pascal - Data from the Android pressure in pascals android_sensor_ambient_light_lux - Data from Android ambient light sensor in lux android_sensor_gyroscope_radians_per_second_squared{axis} - Data from Android gyroscope in radians/second^2 android_sensor_ambient_temperature_celsius - Ambient temperature in celsius android_sensor_rotation_vector{axis} - Data from the Android Rotation Vector sensor, how is the device rotated, without a unit android_sensor_rotation_vector_cosinus_theta_half - Data from the Android Rotation Vector sensor, how is the device rotated, without a unit android_sensor_rotation_vector_accuracy_radians - Android rotation vector sensor accuracy in radians

Android network

android_cellular_network_connected - Whether cellular network is connected android_wifi_connected - Whether WiFi is connected

Miscellaneous

android_battery_charge_ratio - Current battery charge android_battery_is_charging - Whether the battery is charging android_system_info{manufacturer, model, os_release, cpu_core_count} - Information about Android system android_uptime_seconds - Phone uptime in seconds android_scrape_duration_seconds - Duration of the metric scrape

PushProx client mode specific metrics

pushprox_client_poll_errors_total - Number of errored /poll requests pushprox_client_scrape_errors_total - Total number of scrape errors the PushProx client mode has encountered pushprox_client_push_errors_total - Total number of errored /push requests