Add OpenTelemetry Metrics Exporters for Dynatrace

Register a metrics exporters, that forward data to Dynatrace,
if an appropriate service binding is found or do a
non-operation otherwise. This allows developers to explicitly
configure the export, e.g. by `otel.metrics.exporter=dynatrace`.
Additional exporters can be added with comma-separated labels.

Signed-off-by: Karsten Schnitter <[email protected]>

cf-java-logging-support-opentelemetry-agent-extension/src/main/java/com/sap/hcf/cf/logging/opentelemetry/agent/ext/exporter/DynatraceMetricsExporterProvider.java

@@ -0,0 +1,124 @@
+package com.sap.hcf.cf.logging.opentelemetry.agent.ext.exporter;
+
+import io.opentelemetry.exporter.otlp.metrics.OtlpGrpcMetricExporter;
+import io.opentelemetry.exporter.otlp.metrics.OtlpGrpcMetricExporterBuilder;
+import io.opentelemetry.sdk.autoconfigure.spi.ConfigProperties;
+import io.opentelemetry.sdk.autoconfigure.spi.ConfigurationException;
+import io.opentelemetry.sdk.autoconfigure.spi.metrics.ConfigurableMetricExporterProvider;
+import io.opentelemetry.sdk.common.export.RetryPolicy;
+import io.opentelemetry.sdk.metrics.Aggregation;
+import io.opentelemetry.sdk.metrics.InstrumentType;
+import io.opentelemetry.sdk.metrics.export.AggregationTemporalitySelector;
+import io.opentelemetry.sdk.metrics.export.DefaultAggregationSelector;
+import io.opentelemetry.sdk.metrics.export.MetricExporter;
+import io.opentelemetry.sdk.metrics.internal.aggregator.AggregationUtil;
+import io.pivotal.cfenv.core.CfEnv;
+import io.pivotal.cfenv.core.CfService;
+
+import java.time.Duration;
+import java.util.Locale;
+import java.util.function.Function;
+import java.util.logging.Logger;
+
+import static io.opentelemetry.sdk.metrics.Aggregation.explicitBucketHistogram;
+
+public class DynatraceMetricsExporterProvider implements ConfigurableMetricExporterProvider {
+
+    private static final Logger LOG = Logger.getLogger(DynatraceMetricsExporterProvider.class.getName());
+    public static final String CRED_DYNATRACE_APIURL = "apiurl";
+    public static final String DT_APIURL_METRICS_SUFFIX = "/v2/otlp/v1/metrics";
+
+    private final Function<ConfigProperties, CfService> serviceProvider;
+
+    public DynatraceMetricsExporterProvider() {
+        this(config -> new DynatraceServiceProvider(config, new CfEnv()).get());
+    }
+
+    public DynatraceMetricsExporterProvider(Function<ConfigProperties, CfService> serviceProvider) {
+        this.serviceProvider = serviceProvider;
+    }
+
+    private static String getCompression(ConfigProperties config) {
+        String compression = config.getString("otel.exporter.dynatrace.metrics.compression");
+        return compression != null ? compression : config.getString("otel.exporter.dynatrace.compression", "gzip");
+    }
+
+    private static Duration getTimeOut(ConfigProperties config) {
+        Duration timeout = config.getDuration("otel.exporter.dynatrace.metrics.timeout");
+        return timeout != null ? timeout : config.getDuration("otel.exporter.dynatrace.timeout");
+    }
+
+    private static DefaultAggregationSelector getDefaultAggregationSelector(ConfigProperties config) {
+        String defaultHistogramAggregation =
+                config.getString("otel.exporter.dynatrace.metrics.default.histogram.aggregation");
+        if (defaultHistogramAggregation == null) {
+            return DefaultAggregationSelector.getDefault().with(InstrumentType.HISTOGRAM, Aggregation.defaultAggregation());
+        }
+        if (AggregationUtil.aggregationName(Aggregation.base2ExponentialBucketHistogram())
+                .equalsIgnoreCase(defaultHistogramAggregation)) {
+            return
+                    DefaultAggregationSelector.getDefault()
+                            .with(InstrumentType.HISTOGRAM, Aggregation.base2ExponentialBucketHistogram());
+        } else if (AggregationUtil.aggregationName(explicitBucketHistogram())
+                .equalsIgnoreCase(defaultHistogramAggregation)) {
+            return DefaultAggregationSelector.getDefault().with(InstrumentType.HISTOGRAM, Aggregation.explicitBucketHistogram());
+        } else {
+            throw new ConfigurationException(
+                    "Unrecognized default histogram aggregation: " + defaultHistogramAggregation);
+        }
+    }
+
+    @Override
+    public String getName() {
+        return "dynatrace";
+    }
+
+
+    private static boolean isBlank(String text) {
+        return text == null || text.trim().isEmpty();
+    }
+
+    @Override
+    public MetricExporter createExporter(ConfigProperties config) {
+        CfService cfService = serviceProvider.apply(config);
+        if (cfService == null) {
+            LOG.info("No dynatrace service binding found. Skipping metrics exporter registration.");
+            return NoopMetricExporter.getInstance();
+        }
+
+        LOG.info("Creating metrics exporter for service binding " + cfService.getName() + " (" + cfService.getLabel() + ")");
+
+        String apiUrl = cfService.getCredentials().getString(CRED_DYNATRACE_APIURL);
+        if (isBlank(apiUrl)) {
+            LOG.warning("Credential \"" + CRED_DYNATRACE_APIURL + "\" not found. Skipping dynatrace exporter configuration");
+            return NoopMetricExporter.getInstance();
+        }
+        String tokenName = config.getString("otel.javaagent.extension.sap.cf.binding.dynatrace.metrics.token-name");
+        if (isBlank(tokenName)) {
+            LOG.warning("Configuration \"otel.javaagent.extension.sap.cf.binding.dynatrace.metrics.token-name\" not found. Skipping dynatrace exporter configuration");
+            return NoopMetricExporter.getInstance();
+        }
+        String apiToken = cfService.getCredentials().getString(tokenName);
+        if (isBlank(apiUrl)) {
+            LOG.warning("Credential \"" + tokenName + "\" not found. Skipping dynatrace exporter configuration");
+            return NoopMetricExporter.getInstance();
+        }
+
+        OtlpGrpcMetricExporterBuilder builder = OtlpGrpcMetricExporter.builder();
+        builder.setEndpoint(apiUrl + DT_APIURL_METRICS_SUFFIX)
+                .setCompression(getCompression(config))
+                .addHeader("Authorization", "ApiToken " + apiToken)
+                .setRetryPolicy(RetryPolicy.getDefault())
+                .setAggregationTemporalitySelector(AggregationTemporalitySelector.alwaysCumulative())
+                .setDefaultAggregationSelector(getDefaultAggregationSelector(config));
+
+        Duration timeOut = getTimeOut(config);
+        if (timeOut != null) {
+            builder.setTimeout(timeOut);
+        }
+
+        LOG.info("Created metrics exporter for service binding " + cfService.getName() + " (" + cfService.getLabel() + ")");
+        return builder.build();
+    }
+
+}

cf-java-logging-support-opentelemetry-agent-extension/src/main/java/com/sap/hcf/cf/logging/opentelemetry/agent/ext/exporter/DynatraceServiceProvider.java

@@ -0,0 +1,46 @@
+package com.sap.hcf.cf.logging.opentelemetry.agent.ext.exporter;
+
+import io.opentelemetry.sdk.autoconfigure.spi.ConfigProperties;
+import io.pivotal.cfenv.core.CfEnv;
+import io.pivotal.cfenv.core.CfService;
+
+import java.util.List;
+import java.util.function.Supplier;
+import java.util.stream.Stream;
+
+class DynatraceServiceProvider implements Supplier<CfService> {
+
+    private static final String DEFAULT_USER_PROVIDED_LABEL = "user-provided";
+    private static final String DEFAULT_DYNATRACE_LABEL = "dynatrace";
+    private static final String DEFAULT_DYNATRACE_TAG = "dynatrace";
+
+    private final CfService service;
+
+    public DynatraceServiceProvider(ConfigProperties config, CfEnv cfEnv) {
+        String userProvidedLabel = getUserProvidedLabel(config);
+        String dynatraceLabel = getDynatraceLabel(config);
+        String dynatraceTag = getDynatraceTag(config);
+        List<CfService> userProvided = cfEnv.findServicesByLabel(userProvidedLabel);
+        List<CfService> managed = cfEnv.findServicesByLabel(dynatraceLabel);
+        this.service = Stream.concat(userProvided.stream(), managed.stream())
+                .filter(svc -> svc.existsByTagIgnoreCase(dynatraceTag)).findFirst().orElse(null);
+
+    }
+
+    private String getUserProvidedLabel(ConfigProperties config) {
+        return config.getString("otel.javaagent.extension.sap.cf.binding.user-provided.label", DEFAULT_USER_PROVIDED_LABEL);
+    }
+
+    private String getDynatraceLabel(ConfigProperties config) {
+        return config.getString("otel.javaagent.extension.sap.cf.binding.dynatrace.label", DEFAULT_DYNATRACE_LABEL);
+    }
+
+    private String getDynatraceTag(ConfigProperties config) {
+        return config.getString("otel.javaagent.extension.sap.cf.binding.dynatrace.tag", DEFAULT_DYNATRACE_TAG);
+    }
+
+    @Override
+    public CfService get() {
+        return service;
+    }
+}

cf-java-logging-support-opentelemetry-agent-extension/src/main/resources/META-INF/services/io.opentelemetry.sdk.autoconfigure.spi.metrics.ConfigurableMetricExporterProvider

@@ -1 +1,2 @@
-com.sap.hcf.cf.logging.opentelemetry.agent.ext.exporter.CloudLoggingMetricsExporterProvider
+com.sap.hcf.cf.logging.opentelemetry.agent.ext.exporter.CloudLoggingMetricsExporterProvider
+com.sap.hcf.cf.logging.opentelemetry.agent.ext.exporter.DynatraceMetricsExporterProvider