Replace khttp in MetricFetcher

theodolite/src/main/kotlin/rocks/theodolite/kubernetes/slo/ExternalSloChecker.kt

@@ -42,7 +42,7 @@ class ExternalSloChecker(
 
         while (counter < RETRIES) {
             val request = HttpRequest.newBuilder()
-                    .uri(URI(externalSlopeURL))
+                    .uri(URI.create(externalSlopeURL))
                     .POST(HttpRequest.BodyPublishers.ofString(data))
                     .timeout(TIMEOUT)
                     .build()

theodolite/src/main/kotlin/rocks/theodolite/kubernetes/slo/MetricFetcher.kt

 package rocks.theodolite.kubernetes.slo
 
 import com.fasterxml.jackson.databind.ObjectMapper
-import khttp.get
-import khttp.responses.Response
 import mu.KotlinLogging
 import java.net.ConnectException
+import java.net.URI
+import java.net.http.HttpClient
+import java.net.http.HttpRequest
+import java.net.http.HttpResponse
 import java.time.Duration
 import java.time.Instant
 
@@ -18,7 +20,7 @@ private val logger = KotlinLogging.logger {}
  */
 class MetricFetcher(private val prometheusURL: String, private val offset: Duration) {
     private val RETRIES = 2
-    private val TIMEOUT = 60.0
+    private val TIMEOUT = Duration.ofSeconds(60)
 
     /**
      * Tries to fetch a metric by a query to a Prometheus server.
@@ -36,26 +38,27 @@ class MetricFetcher(private val prometheusURL: String, private val offset: Durat
         val offsetEnd = end.minus(offset)
 
         var counter = 0
-        val parameter = mapOf(
-            "query" to query,
-            "start" to offsetStart.toString(),
-            "end" to offsetEnd.toString(),
-            "step" to "5s"
-        )
 
         while (counter < RETRIES) {
             logger.info { "Request collected metrics from Prometheus for interval [$offsetStart,$offsetEnd]." }
-            val response = get("$prometheusURL/api/v1/query_range", params = parameter, timeout = TIMEOUT)
-            if (response.statusCode != 200) {
-                val message = response.jsonObject.toString()
+            val request = HttpRequest.newBuilder()
+                    .uri(URI.create("$prometheusURL/api/v1/query_range?query=$query&start=$offsetStart&end=$offsetEnd&step=5s"))
+                    .GET()
+                    .timeout(TIMEOUT)
+                    .build()
+            val response = HttpClient.newBuilder()
+                    .build()
+                    .send(request, HttpResponse.BodyHandlers.ofString())
+            if (response.statusCode() != 200) {
+                val message = response.body()
                 logger.warn { "Could not connect to Prometheus: $message. Retry $counter/$RETRIES." }
                 counter++
             } else {
-                val values = parseValues(response)
+                val values = parseValues(response.body())
                 if (values.data?.result.isNullOrEmpty()) {
                     throw NoSuchFieldException("Empty query result: $values between for query '$query' in interval [$offsetStart,$offsetEnd] .")
                 }
-                return parseValues(response)
+                return parseValues(response.body())
             }
         }
         throw ConnectException("No answer from Prometheus received.")
@@ -66,9 +69,9 @@ class MetricFetcher(private val prometheusURL: String, private val offset: Durat
      * @param values Response from Prometheus.
      * @return a [PrometheusResponse]
      */
-    private fun parseValues(values: Response): PrometheusResponse {
+    private fun parseValues(values: String): PrometheusResponse {
         return ObjectMapper().readValue<PrometheusResponse>(
-            values.jsonObject.toString(),
+            values,
             PrometheusResponse::class.java
         )
     }