feat: Discovery service health check (#2312)

* Discovery service health check

Signed-off-by: Boris Petkov <boris.petkov@broadcom.com>

* Discovery service health check with Partial status

Signed-off-by: Boris Petkov <boris.petkov@broadcom.com>

Author: Boris Petkov

discovery-service/src/main/java/org/zowe/apiml/discovery/health/DiscoveryServiceHealthIndicator.java

@@ -0,0 +1,37 @@
+/*
+ * This program and the accompanying materials are made available under the terms of the
+ * Eclipse Public License v2.0 which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-v20.html
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Copyright Contributors to the Zowe Project.
+ */
+package org.zowe.apiml.discovery.health;
+
+import lombok.RequiredArgsConstructor;
+import org.springframework.boot.actuate.health.AbstractHealthIndicator;
+import org.springframework.boot.actuate.health.Health;
+import org.springframework.boot.actuate.health.Status;
+import org.springframework.cloud.client.discovery.DiscoveryClient;
+import org.springframework.stereotype.Component;
+import org.zowe.apiml.product.constants.CoreService;
+
+/**
+ * Discovery service health information (/application/health)
+ */
+@Component
+@RequiredArgsConstructor
+public class DiscoveryServiceHealthIndicator extends AbstractHealthIndicator {
+
+    private final DiscoveryClient discoveryClient;
+
+    @Override
+    protected void doHealthCheck(Health.Builder builder) {
+        String gatewayServiceId = CoreService.GATEWAY.getServiceId();
+        boolean gatewayDown = this.discoveryClient.getInstances(gatewayServiceId).isEmpty();
+        builder
+            .status(gatewayDown ? new Status("PARTIAL", "Authenticated endpoints not available.") : Status.UP)
+            .withDetail(gatewayServiceId, gatewayDown ? Status.DOWN : Status.UP);
+    }
+}

discovery-service/src/main/resources/application.yml

@@ -87,6 +87,8 @@ management:
     endpoint:
         shutdown:
             enabled: true
+        health:
+            show-details: always
 
 hystrix.command.default.execution.timeout.enabled: false
 ---

discovery-service/src/test/java/org/zowe/apiml/discovery/health/DiscoveryServiceHealthIndicatorTest.java

@@ -0,0 +1,53 @@
+/*
+ * This program and the accompanying materials are made available under the terms of the
+ * Eclipse Public License v2.0 which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-v20.html
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Copyright Contributors to the Zowe Project.
+ */
+package org.zowe.apiml.discovery.health;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.actuate.health.Health;
+import org.springframework.boot.actuate.health.Status;
+import org.springframework.cloud.client.DefaultServiceInstance;
+import org.springframework.cloud.client.discovery.DiscoveryClient;
+import org.zowe.apiml.product.constants.CoreService;
+
+import java.util.Collections;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+class DiscoveryServiceHealthIndicatorTest {
+
+    private final DiscoveryClient discoveryClient = mock(DiscoveryClient.class);
+    private final DiscoveryServiceHealthIndicator discoverServiceHealthIndicator = new DiscoveryServiceHealthIndicator(discoveryClient);
+    private final Health.Builder builder = new Health.Builder();
+
+    @Test
+    void testStatusIsUpWhenGatewayIsAvailable() {
+        when(discoveryClient.getInstances(CoreService.GATEWAY.getServiceId())).thenReturn(
+            Collections.singletonList(
+                new DefaultServiceInstance(null, CoreService.GATEWAY.getServiceId(), "host", 10010, true)));
+
+        discoverServiceHealthIndicator.doHealthCheck(builder);
+
+        Assertions.assertEquals(Status.UP, builder.build().getStatus());
+        Assertions.assertEquals(Status.UP, builder.build().getDetails().get("gateway"));
+    }
+
+    @Test
+    void testStatusIsPartialWhenGatewayIsNotAvailable() {
+        when(discoveryClient.getInstances(CoreService.GATEWAY.getServiceId())).thenReturn(Collections.emptyList());
+
+        discoverServiceHealthIndicator.doHealthCheck(builder);
+
+        Assertions.assertEquals(new Status("PARTIAL"), builder.build().getStatus());
+        Assertions.assertEquals("Authenticated endpoints not available.", builder.build().getStatus().getDescription());
+        Assertions.assertEquals(Status.DOWN, builder.build().getDetails().get("gateway"));
+    }
+}

discovery-service/src/test/resources/application.yml

@@ -47,6 +47,14 @@ management:
     health:
         defaults:
             enabled: false
+    endpoint:
+        health:
+            status:
+                order: "DOWN,PARTIAL,UP"
+                http-mapping:
+                  DOWN: 503
+                  PARTIAL: 200
+            show-details: always
 ---
 spring:
     profiles: https