SDIT-813: ✨ Add opensearch health indicator (#7)

src/main/kotlin/uk/gov/justice/digital/hmpps/prisonersearchindexer/health/OpenSearchHealthIndicator.kt

@@ -0,0 +1,40 @@
+package uk.gov.justice.digital.hmpps.prisonersearchindexer.health
+
+import org.opensearch.data.client.orhlc.OpenSearchRestTemplate
+import org.springframework.boot.actuate.health.AbstractHealthIndicator
+import org.springframework.boot.actuate.health.Health
+import org.springframework.boot.actuate.health.Status
+import org.springframework.data.elasticsearch.core.cluster.ClusterHealth
+import org.springframework.stereotype.Component
+
+@Suppress("SpringJavaInjectionPointsAutowiringInspection")
+@Component
+class OpenSearchHealthIndicator(private val template: OpenSearchRestTemplate) : AbstractHealthIndicator() {
+  override fun doHealthCheck(builder: Health.Builder): Unit =
+    processResponse(builder, template.cluster().health())
+
+  private fun processResponse(builder: Health.Builder, response: ClusterHealth) {
+    if (response.isTimedOut) {
+      builder.down().build()
+    } else {
+      val status = response.status
+      builder.status(if (status == "RED") Status.OUT_OF_SERVICE else Status.UP)
+      builder.withDetail("cluster_name", response.clusterName)
+      builder.withDetail("status", response.status)
+      builder.withDetail("timed_out", response.isTimedOut)
+      builder.withDetail("number_of_nodes", response.numberOfNodes)
+      builder.withDetail("number_of_data_nodes", response.numberOfDataNodes)
+      builder.withDetail("active_primary_shards", response.activePrimaryShards)
+      builder.withDetail("active_shards", response.activeShards)
+      builder.withDetail("relocating_shards", response.relocatingShards)
+      builder.withDetail("initializing_shards", response.initializingShards)
+      builder.withDetail("unassigned_shards", response.unassignedShards)
+      builder.withDetail("delayed_unassigned_shards", response.delayedUnassignedShards)
+      builder.withDetail("number_of_pending_tasks", response.numberOfPendingTasks)
+      builder.withDetail("number_of_in_flight_fetch", response.numberOfInFlightFetch)
+      builder.withDetail("task_max_waiting_in_queue_millis", response.taskMaxWaitingTimeMillis)
+      builder.withDetail("active_shards_percent_as_number", response.activeShardsPercent)
+      builder.build()
+    }
+  }
+}

src/test/kotlin/uk/gov/justice/digital/hmpps/prisonersearchindexer/integration/health/HealthCheckTest.kt

@@ -85,6 +85,16 @@ class HealthCheckTest : IntegrationTestBase() {
       .jsonPath("status").isEqualTo("UP")
   }
 
+  @Test
+  fun `health check reports opensearch status`() {
+    stubPingWithResponse(200)
+
+    webTestClient.get().uri("/health")
+      .exchange()
+      .expectStatus().isOk
+      .expectBody().jsonPath("components.openSearch.status").isEqualTo("UP")
+  }
+
   private fun stubPingWithResponse(status: Int) {
     hmppsAuth.stubHealthPing(status)
     restrictedPatientsApi.stubHealthPing(status)