prometheus server and pushprox working

README.md

@@ -1,11 +1,29 @@
 # prometheus-android-exporter
-Prometheus exporter for android
+Prometheus exporter for android phones. Can traverse NAT by leveraging PushProx proxy. Not intended
+to run as ROOT. Exposes various hardware sensor metrics.
+
+# Repository contents
+- Folder ./client contains Jetpack Compose android Prometheus exporter written in kotlin.
+- 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 to spin up prometheus database on localhost
+    quickly.
 
 # Not public
 143.42.59.63:9090 - prometheus
 
 # Client
-Android app written in kotlin using Jetpack Compose.
+
+### ADB port forwarding
+ADB port forwarding is usefull when running the client application 
+on 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
 

client/app/build.gradle

@@ -62,6 +62,10 @@ dependencies {
     implementation("io.ktor:ktor-client-core:2.3.0")
     implementation("io.ktor:ktor-client-cio:2.3.0")
 
+    // ktor web server
+    implementation "io.ktor:ktor-server-cio:2.3.0"
+    implementation "io.ktor:ktor-server-core:2.3.0"
+
 
     implementation 'androidx.core:core-ktx:1.7.0'
     implementation 'androidx.lifecycle:lifecycle-runtime-ktx:2.3.1'

client/app/src/main/java/com/birdthedeveloper/prometheus/android/prometheus/android/exporter/MainActivity.kt

@@ -4,6 +4,7 @@ import android.os.Bundle
 import android.text.BoringLayout.Metrics
 import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
+import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.material.Button
 import androidx.compose.material.MaterialTheme
@@ -22,6 +23,7 @@ import kotlinx.coroutines.delay
 import kotlinx.coroutines.launch
 import java.io.StringWriter
 
+//https://www.geeksforgeeks.org/how-to-launch-an-application-automatically-on-system-boot-up-in-android/
 class MainActivity : ComponentActivity() {
 
     private val collectorRegistry: CollectorRegistry = CollectorRegistry()
@@ -83,19 +85,36 @@ class MainActivity : ComponentActivity() {
         return writer.toString()
     }
 
+    private fun startPromServer(){
+        //TODO impl
+        val promServer : PrometheusServer = PrometheusServer(
+            config = PrometheusServerConfig(
+                8080,
+                ::reallyCollectMetrics
+            )
+        )
+        promServer.startBackground()
+    }
+
     @Composable
     fun PrometheusHomepage() {
+        Column {
             Button(onClick = {
                 println(CollectMetrics())
             }) {
                 Text("Click this button")
             }
+            Button(onClick = ::startPromServer){
+                Text("Prometheus server")
+            }
+        }
     }
 }
 
 //TODO how to call coroutine / async from custom collector
 //TODO how to extract any hw system metric from android API
 //TODO how to get permission on first application start only
+//TODO viewmodel, state management
 
 //class GlobalViewModel : ViewModel() {
 //    val state = mutableStateOf<Int>(Resource.Success(i))

client/app/src/main/java/com/birdthedeveloper/prometheus/android/prometheus/android/exporter/PrometheusServer.kt

@@ -0,0 +1,70 @@
+package com.birdthedeveloper.prometheus.android.prometheus.android.exporter
+
+import android.util.Log
+import io.ktor.server.application.call
+import io.ktor.server.engine.*
+import io.ktor.server.cio.*
+import io.ktor.server.response.respondText
+import io.ktor.server.routing.get
+import io.ktor.server.routing.routing
+import kotlinx.coroutines.GlobalScope
+import kotlinx.coroutines.launch
+
+fun something(){
+    //TODO
+
+}
+
+// Configuration object for PrometheusServer class
+data class PrometheusServerConfig(
+    val port : Int = 8080,
+    val performScrape : suspend () -> String,
+)
+
+// Expose metrics on given port using Ktor http server
+class PrometheusServer(config: PrometheusServerConfig){
+    private  val config : PrometheusServerConfig
+    private lateinit var server : ApplicationEngine
+
+    init {
+        this.config = config
+    }
+
+    private suspend fun getMetrics() : String{
+        val result : String = try{
+            config.performScrape()
+        }catch(e: Exception){
+            ""
+        }
+
+        return result
+    }
+
+    private fun configureServer(){
+        server = embeddedServer(CIO, port = config.port) {
+            routing {
+                get("/") {
+                    call.respondText("Prometheus Android Exporter")
+                }
+                get("/metrics") {
+                    call.respondText(getMetrics())
+                }
+            }
+        }
+    }
+
+    fun startBackground(){
+        configureServer()
+
+        GlobalScope.launch {
+            launch{
+                server.start(wait = true)
+            }
+        }
+        log("startBackground", "done")
+    }
+
+    private fun log(title: String, text: String) {
+        Log.v("PROMETHEUS SERVER", "$title: $text")
+    }
+}

local/docker-compose.yaml

@@ -0,0 +1,12 @@
+# Simple run of prometheus database with a configuration file on localhost
+
+version: '3.9'
+
+services:
+  prometheus:
+    container_name: prometheus
+    image: bitnami/prometheus:2.43.0
+    restart: on-failure
+    volumes:
+      - ./prometheus.yaml:/etc/prometheus/prometheus.yml
+    network_mode: host

local/prometheus.yaml

@@ -0,0 +1,15 @@
+# Prometheus global configuration file
+global:
+  scrape_interval: 5s # Set the scrape interval to every 15 seconds. Default is every 1 minute.
+  evaluation_interval: 15s # Evaluate rules every 15 seconds. The default is every 1 minute.
+scrape_configs:
+  - job_name: "prometheus"
+
+    static_configs:
+      - targets: ["localhost:9090"] # scrape prometheus itself
+  
+  - job_name: "android phones"
+    static_configs:
+      - targets: [
+          "localhost:8080"
+        ]