chore | adding the metrics for api count (#273)

* chore | adding the metrics for api count

Author: aman-bansal

entity-service-impl/src/main/java/org/hypertrace/entity/metric/EntityMetricsReporter.java

@@ -1,18 +1,78 @@
 package org.hypertrace.entity.metric;
 
+import static org.hypertrace.core.documentstore.expression.operators.AggregationOperator.COUNT;
+import static org.hypertrace.core.documentstore.model.config.CustomMetricConfig.VALUE_KEY;
+
+import java.time.Duration;
+import java.util.List;
 import org.hypertrace.core.documentstore.Datastore;
+import org.hypertrace.core.documentstore.expression.impl.AggregateExpression;
+import org.hypertrace.core.documentstore.expression.impl.ConstantExpression;
+import org.hypertrace.core.documentstore.expression.impl.IdentifierExpression;
+import org.hypertrace.core.documentstore.expression.impl.RelationalExpression;
+import org.hypertrace.core.documentstore.expression.operators.RelationalOperator;
+import org.hypertrace.core.documentstore.model.config.CustomMetricConfig;
+import org.hypertrace.core.documentstore.query.Filter;
+import org.hypertrace.core.documentstore.query.Query;
+import org.hypertrace.core.serviceframework.docstore.metrics.DocStoreCustomMetricReportingConfig;
 import org.hypertrace.core.serviceframework.docstore.metrics.DocStoreMetricsRegistry;
 import org.hypertrace.core.serviceframework.spi.PlatformServiceLifecycle;
+import org.hypertrace.entity.v1.entitytype.EntityType;
 
 public class EntityMetricsReporter {
+
+  private static final String API_COUNT_METRIC_NAME = "api.entities.count";
+  private static final String RAW_ENTITIES_COLLECTION = "raw_entities";
+  private static final String API_DISCOVERY_STATE_ENTITY_PATH =
+      "attributes.api_discovery_state.value.string";
+  private static final String TENANT_ID_ENTITY_PATH = "tenantId";
+  private static final String ENTITY_TYPE_ENTITY_PATH = "entityType";
   private final DocStoreMetricsRegistry metricsRegistry;
 
   public EntityMetricsReporter(
       final Datastore datastore, final PlatformServiceLifecycle lifecycle) {
-    metricsRegistry = new DocStoreMetricsRegistry(datastore).withPlatformLifecycle(lifecycle);
+    metricsRegistry =
+        new DocStoreMetricsRegistry(datastore)
+            .withPlatformLifecycle(lifecycle)
+            .withCustomMetrics(apiCounterConfig);
   }
 
   public void monitor() {
     metricsRegistry.monitor();
   }
+
+  @SuppressWarnings("FieldCanBeLocal")
+  private final List<DocStoreCustomMetricReportingConfig> apiCounterConfig =
+      List.of(
+          DocStoreCustomMetricReportingConfig.builder()
+              .reportingInterval(Duration.ofHours(1))
+              .config(
+                  CustomMetricConfig.builder()
+                      .metricName(API_COUNT_METRIC_NAME)
+                      .collectionName(RAW_ENTITIES_COLLECTION)
+                      .query(
+                          Query.builder()
+                              .setFilter(getFilter())
+                              .addSelection(IdentifierExpression.of(TENANT_ID_ENTITY_PATH))
+                              .addSelection(
+                                  AggregateExpression.of(COUNT, ConstantExpression.of(1)),
+                                  VALUE_KEY)
+                              .addSelection(
+                                  IdentifierExpression.of(API_DISCOVERY_STATE_ENTITY_PATH))
+                              .addAggregation(IdentifierExpression.of(TENANT_ID_ENTITY_PATH))
+                              .addAggregation(
+                                  IdentifierExpression.of(API_DISCOVERY_STATE_ENTITY_PATH))
+                              .build())
+                      .build())
+              .build());
+
+  private Filter getFilter() {
+    return Filter.builder()
+        .expression(
+            RelationalExpression.of(
+                IdentifierExpression.of(ENTITY_TYPE_ENTITY_PATH),
+                RelationalOperator.EQ,
+                ConstantExpression.of(EntityType.API.name())))
+        .build();
+  }
 }