refactor: update exception handling to use specific exception types (#1843)

Signed-off-by: Gregor Zeitlinger <gregor.zeitlinger@grafana.com>

Author: zeitlinger

prometheus-metrics-exporter-httpserver/src/main/java/io/prometheus/metrics/exporter/httpserver/HttpExchangeAdapter.java

@@ -112,7 +112,7 @@ private void sendErrorResponseWithStackTrace(Exception requestHandlerException)
         httpExchange.getResponseHeaders().set("Content-Type", "text/plain; charset=utf-8");
         httpExchange.sendResponseHeaders(500, stackTrace.length);
         httpExchange.getResponseBody().write(stackTrace);
-      } catch (Exception errorWriterException) {
+      } catch (IOException errorWriterException) {
         // We want to avoid logging so that we don't mess with application logs when the HTTPServer
         // is used in a Java agent.
         // However, if we can't even send an error response to the client there's nothing we can do

prometheus-metrics-exporter-opentelemetry/src/main/java/io/prometheus/metrics/exporter/opentelemetry/OtelAutoConfig.java

@@ -112,7 +112,7 @@ static Resource getResourceField(AutoConfiguredOpenTelemetrySdk sdk) {
       Method method = AutoConfiguredOpenTelemetrySdk.class.getDeclaredMethod("getResource");
       method.setAccessible(true);
       return (Resource) method.invoke(sdk);
-    } catch (Exception e) {
+    } catch (ReflectiveOperationException e) {
       throw new RuntimeException(e);
     }
   }

prometheus-metrics-exporter-opentelemetry/src/main/java/io/prometheus/metrics/exporter/opentelemetry/PrometheusInstrumentationScope.java

@@ -1,6 +1,8 @@
 package io.prometheus.metrics.exporter.opentelemetry;
 
 import io.opentelemetry.sdk.common.InstrumentationScopeInfo;
+import java.io.IOException;
+import java.io.InputStream;
 import java.util.Properties;
 
 class PrometheusInstrumentationScope {
@@ -21,8 +23,15 @@ static InstrumentationScopeInfo loadInstrumentationScopeInfo(
       String path, String nameKey, String versionKey) {
     try {
       Properties properties = new Properties();
-      properties.load(
-          PrometheusInstrumentationScope.class.getClassLoader().getResourceAsStream(path));
+      InputStream stream =
+          PrometheusInstrumentationScope.class.getClassLoader().getResourceAsStream(path);
+      if (stream == null) {
+        throw new IllegalStateException(
+            "Prometheus metrics library initialization error: Failed to read "
+                + path
+                + " from classpath.");
+      }
+      properties.load(stream);
       String instrumentationScopeName = properties.getProperty(nameKey);
       if (instrumentationScopeName == null) {
         throw new IllegalStateException(
@@ -44,7 +53,7 @@ static InstrumentationScopeInfo loadInstrumentationScopeInfo(
       return InstrumentationScopeInfo.builder(instrumentationScopeName)
           .setVersion(instrumentationScopeVersion)
           .build();
-    } catch (Exception e) {
+    } catch (IOException e) {
       throw new IllegalStateException(
           "Prometheus metrics library initialization error: Failed to read "
               + path

prometheus-metrics-exporter-opentelemetry/src/test/java/io/prometheus/metrics/exporter/opentelemetry/PrometheusInstrumentationScopeTest.java

@@ -22,7 +22,6 @@ void loadInstrumentationScopeInfo() {
             () ->
                 PrometheusInstrumentationScope.loadInstrumentationScopeInfo(
                     "instrumentationScope.properties", "name", "version"))
-        .havingRootCause()
         .withMessage(
             "Prometheus metrics library initialization error: name not found in"
                 + " instrumentationScope.properties in classpath.");
@@ -32,7 +31,6 @@ void loadInstrumentationScopeInfo() {
             () ->
                 PrometheusInstrumentationScope.loadInstrumentationScopeInfo(
                     "instrumentationScope.properties", "instrumentationScope.name", "version"))
-        .havingRootCause()
         .withMessage(
             "Prometheus metrics library initialization error: version not found in"
                 + " instrumentationScope.properties in classpath.");

prometheus-metrics-instrumentation-caffeine/src/main/java/io/prometheus/metrics/instrumentation/caffeine/CacheMetricsCollector.java

@@ -226,7 +226,7 @@ public MetricSnapshots collect() {
                 .labels(labels)
                 .value(stats.evictionWeight())
                 .build());
-      } catch (Exception e) {
+      } catch (UnsupportedOperationException e) {
         // EvictionWeight metric is unavailable, newer version of Caffeine is needed.
       }
 

prometheus-metrics-instrumentation-dropwizard5/src/main/java/io/prometheus/metrics/instrumentation/dropwizard5/internal/AbstractDropwizardExports.java

@@ -195,7 +195,7 @@ protected <K, V> void collectMetricKind(
         if (snapshot != null) {
           builder.metricSnapshot(snapshot);
         }
-      } catch (Exception e) {
+      } catch (RuntimeException e) {
         if (!invalidMetricHandler.suppressException(metricName, e)) {
           throw e;
         }

prometheus-metrics-instrumentation-jvm/src/main/java/io/prometheus/metrics/instrumentation/jvm/JvmNativeMemoryMetrics.java

@@ -163,8 +163,8 @@ private String vmNativeMemorySummaryInBytesOrEmpty() {
       } else {
         return summary;
       }
-    } catch (Exception ex) {
-      // ignore errors
+    } catch (RuntimeException ex) {
+      // ignore errors (native memory tracking not enabled or other runtime failures)
       isEnabled.set(false);
       return "";
     }