pushprox worker kinda works

client/app/build.gradle

@@ -73,6 +73,9 @@ dependencies {
     def nav_version = "2.5.3"
     implementation("androidx.navigation:navigation-compose:$nav_version")
 
+    // custom - work manager
+    implementation 'androidx.work:work-runtime-ktx:2.7.1'
+
 
     implementation 'androidx.core:core-ktx:1.10.0'
     implementation 'androidx.lifecycle:lifecycle-runtime-ktx:2.6.1'
@@ -87,7 +90,3 @@ dependencies {
     debugImplementation "androidx.compose.ui:ui-tooling:$compose_ui_version"
     debugImplementation "androidx.compose.ui:ui-test-manifest:$compose_ui_version"
 }
-
-dependencies {
-
-}

client/app/src/main/AndroidManifest.xml

@@ -16,7 +16,6 @@
         <activity
             android:name=".MainActivity"
             android:exported="true"
-            android:label="@string/app_name"
             android:theme="@style/Theme.PrometheusAndroidExporter">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
@@ -24,6 +23,12 @@
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
+
+        <service
+            android:name="androidx.work.impl.foreground.SystemForegroundService"
+            android:foregroundServiceType="location|microphone"
+            tools:node="merge" />
+
     </application>
 
 </manifest>

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

@@ -0,0 +1,29 @@
+package com.birdthedeveloper.prometheus.android.prometheus.android.exporter
+
+import androidx.work.Data
+
+data class PushProxConfig(
+    val pushProxUrl : String,
+    val pushProxFqdn : String,
+){
+    companion object{
+        fun fromData(data : Data) : PushProxConfig{
+            return PushProxConfig(
+                data.getString("0")!!,
+                data.getString("1")!!,
+            )
+        }
+    }
+
+    fun toData() : Data {
+        return Data.Builder()
+            .putString("0", pushProxUrl)
+            .putString("1", pushProxFqdn)
+            .build()
+    }
+}
+
+data class PromServerConfig(
+    //TODO implement this
+    val dummy : String,
+)

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

@@ -159,10 +159,10 @@ private fun onCheckedChangePushProx(
     value : Boolean,
     promViewModel: PromViewModel,
     showDialog : MutableState<String>
-){
+) {
     if (value) {
-        val result : String? = promViewModel.turnPushProxOn()
+        val result: String? = promViewModel.turnPushProxOn()
-        if(result != null){
+        if (result != null) {
             showDialog.value = result
         }
     } else {
@@ -176,7 +176,7 @@ private fun PushProxPage(
 ){
     val uiState : PromUiState by promViewModel.uiState.collectAsState()
 
-    // if showDialogText == "", do not display alert dialog
+    // if showDialogText is empty string, do not display alert dialog
     val showDialogText : MutableState<String> = remember { mutableStateOf("") }
 
     Column(
@@ -193,8 +193,20 @@ private fun PushProxPage(
             modifier = Modifier.padding(bottom = 30.dp)
         )
 
+        if(uiState.pushProxTurnedOn){
+            Text(
+                text = """
+                    To edit PushProx proxy URL or FQDN, turn it off first.
+                """.trimIndent(),
+                textAlign = TextAlign.Center,
+                modifier = Modifier.padding(bottom = 12.dp),
+            )
+        }
+
         TextField(
             value = uiState.fqdn,
+            singleLine = true,
+            enabled = !uiState.pushProxTurnedOn,
             onValueChange = {
                 promViewModel.updatePushProxFQDN(it)
             },
@@ -206,6 +218,8 @@ private fun PushProxPage(
 
         TextField(
             value = uiState.pushProxURL,
+            singleLine = true,
+            enabled = !uiState.pushProxTurnedOn,
             onValueChange = {
                 promViewModel.updatePushProxURL(it)
             },

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

@@ -1,34 +1,19 @@
 package com.birdthedeveloper.prometheus.android.prometheus.android.exporter
 
 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
 import androidx.compose.material.Surface
-import androidx.compose.material.Text
 import androidx.compose.runtime.Composable
-import androidx.compose.runtime.mutableStateOf
 import androidx.compose.ui.Modifier
-import androidx.lifecycle.ViewModel
 import androidx.lifecycle.ViewModelProvider
-import androidx.lifecycle.viewModelScope
-import androidx.lifecycle.viewmodel.compose.viewModel
-import androidx.navigation.NavController
 import androidx.navigation.NavHostController
 import androidx.navigation.compose.NavHost
 import androidx.navigation.compose.composable
 import androidx.navigation.compose.rememberNavController
 import com.birdthedeveloper.prometheus.android.prometheus.android.exporter.ui.theme.PrometheusAndroidExporterTheme
-import io.prometheus.client.Collector
-import io.prometheus.client.CollectorRegistry
-import io.prometheus.client.exporter.common.TextFormat
-import kotlinx.coroutines.delay
-import kotlinx.coroutines.launch
-import java.io.StringWriter
 
 //TODO
 //https://www.geeksforgeeks.org/how-to-launch-an-application-automatically-on-system-boot-up-in-android/
@@ -39,7 +24,7 @@ class MainActivity : ComponentActivity() {
         super.onCreate(savedInstanceState)
 
         val promViewModel: PromViewModel = ViewModelProvider(this)[PromViewModel::class.java]
-        promViewModel.setApplicationContext { this.applicationContext }
+        promViewModel.initializeWithApplicationContext { this.applicationContext }
 
         setContent {
             PrometheusAndroidExporterTheme {

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

@@ -0,0 +1,2 @@
+package com.birdthedeveloper.prometheus.android.prometheus.android.exporter
+

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

@@ -4,9 +4,16 @@ import android.content.Context
 import android.util.Log
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
+import androidx.work.Constraints
+import androidx.work.Data
+import androidx.work.ExistingWorkPolicy
+import androidx.work.NetworkType
+import androidx.work.OneTimeWorkRequestBuilder
+import androidx.work.Operation
+import androidx.work.OutOfQuotaPolicy
+import androidx.work.WorkManager
 import io.prometheus.client.CollectorRegistry
 import io.prometheus.client.exporter.common.TextFormat
-import kotlinx.coroutines.GlobalScope
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
@@ -27,28 +34,28 @@ data class PromUiState(
     val serverTurnedOn : Boolean = false,
     val pushProxTurnedOn : Boolean = false,
     val serverPort : Int? = null, // if null, use default port
-    val fqdn : String = "",
+    val fqdn : String = "test.example.com",
-    val pushProxURL : String = "",
+    val pushProxURL : String = "143.42.59.63:8080",
     val configFileState : ConfigFileState = ConfigFileState.LOADING,
 )
 
 private val TAG : String = "PROMVIEWMODEL"
 
 class PromViewModel(): ViewModel() {
+    // constants
     private val DEFAULT_SERVER_PORT : Int = 10101 //TODO register with prometheus community
+    private val PROM_UNIQUE_WORK : String = "prom_unique_job"
+
+
     private val _uiState = MutableStateFlow(PromUiState())
     val uiState : StateFlow<PromUiState> = _uiState.asStateFlow()
 
-    // app - level components
+    private lateinit var getContext: () -> Context
-    private val collectorRegistry: CollectorRegistry = CollectorRegistry()
-    private lateinit var pushProxClient : PushProxClient
-    private val prometheusServer : PrometheusServer = PrometheusServer()
-    private lateinit var metricsEngine: MetricsEngine
-    private lateinit var androidCustomExporter: AndroidCustomExporter
 
     init {
         Log.v(TAG, "Checking for configuration file")
         viewModelScope.launch {
+            //TODO check for configuration file
             delay(1000)
             _uiState.update { current ->
                 current.copy(configFileState = ConfigFileState.MISSING)
@@ -60,13 +67,8 @@ class PromViewModel(): ViewModel() {
         return DEFAULT_SERVER_PORT
     }
 
-    fun setApplicationContext(getContext : () -> Context){
+    fun initializeWithApplicationContext(getContext : () -> Context){
-        // initalize app - level components
+        this.getContext = getContext
-        metricsEngine = MetricsEngine(getContext())
-        androidCustomExporter = AndroidCustomExporter(metricsEngine).register(collectorRegistry)
-        pushProxClient = PushProxClient(collectorRegistry)
-        //TODO somehow this PushProx definition does not work here
-        // -> fix it
     }
 
     fun updateTabIndex(index : Int){
@@ -85,22 +87,16 @@ class PromViewModel(): ViewModel() {
         }
     }
 
-    private suspend fun performScrape() : String {
-        val writer : StringWriter = StringWriter()
-        TextFormat.write004(writer, collectorRegistry.metricFamilySamples())
-
-        return writer.toString()
-    }
-
     // if result is not null, it contains an error message
     fun turnServerOn() : String?{
         try{
-            prometheusServer.startInBackground(
+            //TODO rewrite asap
-                PrometheusServerConfig(
+//            prometheusServer.startInBackground(
-                    getPromServerPort(),
+//                PrometheusServerConfig(
-                    ::performScrape
+//                    getPromServerPort(),
-                )
+//                    ::performScrape
-            )
+//                )
+//            )
         }catch(e : Exception){
             Log.v(TAG, e.toString())
             return "Prometheus server failed!"
@@ -119,8 +115,8 @@ class PromViewModel(): ViewModel() {
     }
 
     private fun validatePushProxSettings() : String? {
-        val fqdn = _uiState.value.fqdn.trim()
+        val fqdn = _uiState.value.fqdn.trim().trim('\n')
-        val url = _uiState.value.pushProxURL.trim()
+        val url = _uiState.value.pushProxURL.trim().trim('\n')
 
         if( fqdn.isEmpty() ) return "Fully Qualified Domain Name cannot be empty!"
         if( url.isEmpty() ) return "PushProx URL cannot be empty!"
@@ -128,25 +124,42 @@ class PromViewModel(): ViewModel() {
         return null
     }
 
+    private fun launchPushProxUsingWorkManager(){
+        val workManagerInstance = WorkManager.getInstance(getContext())
+
+        // worker configuration
+        val inputData : Data = PushProxConfig(
+            pushProxFqdn = _uiState.value.fqdn,
+            pushProxUrl = _uiState.value.pushProxURL,
+        ).toData()
+
+        // constraints
+        val constraints = Constraints.Builder()
+            .setRequiredNetworkType(NetworkType.NOT_REQUIRED)
+            .build()
+
+        // setup worker request
+        val workerRequest = OneTimeWorkRequestBuilder<PushProxWorker>()
+            .setInputData(inputData)
+            .setConstraints(constraints)
+            .setExpedited(OutOfQuotaPolicy.RUN_AS_NON_EXPEDITED_WORK_REQUEST)
+            .build()
+
+        // enqueue
+        workManagerInstance.beginUniqueWork(
+            PROM_UNIQUE_WORK,
+            ExistingWorkPolicy.KEEP,
+            workerRequest,
+        ).enqueue()
+    }
+
     // if result is not null, it contains an error message
     fun turnPushProxOn() : String?{
-
         val error : String? = validatePushProxSettings()
-        if(error != null){
+        if(error != null){ return error }
-            return error
-        }
 
-        try{
+        // idempotent call
-            pushProxClient.startBackground(
+        launchPushProxUsingWorkManager()
-                PushProxConfig(
-                    performScrape = ::performScrape,
-                    fqdn = _uiState.value.fqdn.trim(),
-                    proxyUrl = _uiState.value.pushProxURL.trim(),
-                )
-            )
-        }catch(e : Exception){
-            return "PushProx client failed!"
-        }
 
         _uiState.update { current ->
             current.copy(
@@ -158,7 +171,14 @@ class PromViewModel(): ViewModel() {
     }
 
     fun turnPushProxOff(){
-        //TODO implement
+        val workerManagerInstance = WorkManager.getInstance(getContext())
+        workerManagerInstance.cancelUniqueWork(PROM_UNIQUE_WORK)
+
+        _uiState.update {current ->
+            current.copy(
+                pushProxTurnedOn = false
+            )
+        }
     }
 
     fun updatePushProxURL(url : String){

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

@@ -12,6 +12,7 @@ import io.ktor.client.statement.HttpResponse
 import io.ktor.http.HttpMethod
 import io.prometheus.client.CollectorRegistry
 import io.prometheus.client.Counter
+import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.GlobalScope
 import kotlinx.coroutines.launch
 
@@ -51,13 +52,6 @@ private class Counters(collectorRegistry: CollectorRegistry) {
     fun pollError(){ pollErrorCounter.inc() }
 }
 
-// Configuration object for this pushprox client
-data class PushProxConfig(
-    val fqdn: String,
-    val proxyUrl: String,
-    val performScrape: suspend () -> String,
-)
-
 // Error in parsing HTTP header "Id" from HTTP request from Prometheus
 class PushProxIdParseException(message: String) : Exception(message)
 
@@ -68,31 +62,26 @@ data class PushProxContext(
     val pushUrl : String,
     val backoff : StrategyBackoff<Unit>,
     val fqdn : String,
-    val performScrape: suspend () -> String,
 )
 
 // This is a stripped down kotlin implementation of github.com/prometheus-community/PushProx client
 class PushProxClient(
-    private val collectorRegistry: CollectorRegistry
+    collectorRegistry: CollectorRegistry,
+    private val performScrape: suspend () -> String
 ) {
     private val counters : Counters = Counters(collectorRegistry)
     private val retryInitialWaitSeconds : Int = 1
     private val retryMaxWaitSeconds : Int = 5
-    private var isRunning : Boolean = false
 
     // Use this function to start exporting metrics to pushprox in the background
-    fun startBackground(config: PushProxConfig) {
+    suspend fun startBackground(config: PushProxConfig) {
-        if(!isRunning){
-            isRunning = true
-
             val client : HttpClient = HttpClient() //TODO close this thing
             val context : PushProxContext = processConfig(client, config)
             loop(context)
     }
-    }
 
     private fun processConfig(client : HttpClient, config : PushProxConfig) : PushProxContext {
-        var modifiedProxyURL = config.proxyUrl.trim('/')
+        var modifiedProxyURL = config.pushProxUrl.trim('/')
 
         if(
             !modifiedProxyURL.startsWith("http://") &&
@@ -109,8 +98,7 @@ class PushProxClient(
             pollURL,
             pushURL,
             newBackoffFromFlags(),
-            config.fqdn,
+            config.pushProxFqdn,
-            config.performScrape,
         )
     }
 
@@ -143,7 +131,6 @@ class PushProxClient(
             "X-Prometheus-Scrape-Timeout: 9.5\r\n"
 
         val result : String = httpHeaders + "\r\n" + scrapedMetrics
-        log("result", result)
         return result
     }
 
@@ -152,7 +139,7 @@ class PushProxClient(
         // perform scrape
         lateinit var scrapedMetrics : String
         try {
-            scrapedMetrics = context.performScrape()
+            scrapedMetrics = performScrape()
         }catch(e : Exception){
             counters.scrapeError()
             log("scrape exception", e.toString())
@@ -173,7 +160,6 @@ class PushProxClient(
             log("push exception", e.toString())
             return
         }
-
     }
 
     private fun newBackoffFromFlags() : StrategyBackoff<Unit> {
@@ -187,27 +173,27 @@ class PushProxClient(
     }
 
     //TODO migrate to work manager
-    private fun loop(context : PushProxContext) {
+    private suspend fun loop(context : PushProxContext) {
-        // fire and forget a new coroutine
+        var shouldContinue : Boolean = true
-        GlobalScope.launch {
+        while (shouldContinue) {
-            launch {
-                while (true) {
-                    val job = launch {
             log("pushprox main loop", "loop start")
-                        var result = context.backoff.withRetries {
             // register poll error using try-catch block
             try {
                 doPoll(context)
-                            } catch (e: Exception) {
+            }catch(e : CancellationException){
+                shouldContinue = false
+            }
+            catch (e: Exception) {
+                for(exception in e.suppressed){
+                    if(exception is CancellationException){
+                        shouldContinue = false
+                    }
+                }
                 log("exception encountered!", e.toString())
                 counters.pollError()
                 throw e
             }
-                        }
+            log("pushprox main loop", "loop end")
-                    }
-                    job.join() // wait for the job to finish
-                }
-            }
         }
     }
 

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

@@ -0,0 +1,81 @@
+package com.birdthedeveloper.prometheus.android.prometheus.android.exporter
+
+import android.content.Context
+import android.util.Log
+import androidx.core.app.NotificationCompat
+import androidx.work.CoroutineWorker
+import androidx.work.Data
+import androidx.work.ForegroundInfo
+import androidx.work.WorkManager
+import androidx.work.WorkerParameters
+import io.prometheus.client.CollectorRegistry
+import io.prometheus.client.exporter.common.TextFormat
+import kotlinx.coroutines.delay
+import java.io.StringWriter
+
+private val TAG = "PUSH_PROX_WORKER"
+
+class PushProxWorker(
+    private val context : Context,
+    parameters : WorkerParameters
+): CoroutineWorker(context, parameters){
+
+    override suspend fun doWork():Result {
+        //TODO implement this
+        val cache: PushProxWorkerCache = PushProxWorkerCache.getInstance {
+            return@getInstance context
+        }
+
+        try{
+            val pushProxConfig : PushProxConfig = PushProxConfig.fromData(inputData)
+
+            cache.startBackground(pushProxConfig)
+
+        }catch(e : Exception){
+            Log.v(TAG, e.toString())
+            return Result.failure()
+        }
+
+        return Result.success()
+    }
+}
+
+// thread-safe singleton
+class PushProxWorkerCache private constructor(
+    private val getContext: () -> Context
+){
+    private val collectorRegistry: CollectorRegistry = CollectorRegistry()
+    private val metricsEngine : MetricsEngine = MetricsEngine(getContext())
+    private val pushProxClient = PushProxClient(collectorRegistry, ::performScrape)
+    private lateinit var androidCustomExporter : AndroidCustomExporter
+
+    init {
+        Log.v(TAG, "Initializing WorkerCache")
+        androidCustomExporter = AndroidCustomExporter(metricsEngine).register(collectorRegistry)
+    }
+
+    private fun performScrape() : String{
+        val writer = StringWriter()
+        TextFormat.write004(writer, collectorRegistry.metricFamilySamples())
+        return writer.toString()
+    }
+
+    suspend fun startBackground(pushProxConfig : PushProxConfig){
+        pushProxClient.startBackground(pushProxConfig)
+    }
+
+    companion object {
+        private var instance : PushProxWorkerCache? = null
+
+        fun getInstance(getContext: () -> Context) : PushProxWorkerCache {
+            if(instance == null){
+                synchronized(PushProxWorkerCache::class.java){
+                    if (instance == null){
+                        instance = PushProxWorkerCache(getContext)
+                    }
+                }
+            }
+            return instance!!
+        }
+    }
+}