Added PingHealthCheck.

src/main/java/nl/knaw/dans/lib/util/PingHealthCheck.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2021 DANS - Data Archiving and Networked Services (info@dans.knaw.nl)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package nl.knaw.dans.lib.util;
+
+import com.codahale.metrics.health.HealthCheck;
+import lombok.AllArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+
+import javax.ws.rs.client.Client;
+import javax.ws.rs.core.MediaType;
+import javax.ws.rs.core.Response;
+import java.net.URI;
+
+/**
+ * Health check for a service that responds to a ping request with "pong".
+ */
+@Slf4j
+@AllArgsConstructor
+public class PingHealthCheck extends HealthCheck {
+    private final String name;
+    private final Client httpClient;
+    private final URI pingUri;
+
+    @Override
+    protected Result check() {
+        try (Response response = httpClient.target(pingUri)
+            .request(MediaType.TEXT_PLAIN)
+            .get()) {
+
+            if (response.getStatus() == 200) {
+                String content = response.readEntity(String.class);
+
+                if (!"pong".equals(content.trim())) {
+                    return Result.unhealthy("%s ping URL did not respond with 'pong'", name);
+                }
+                else {
+                    return Result.healthy();
+                }
+            }
+            else {
+                return Result.unhealthy("Service responded with unexpected status: %d %s", response.getStatus(), response.getStatusInfo());
+            }
+        }
+        catch (Throwable e) {
+            return Result.unhealthy("Connection to %s could not be established: %s", name, e.getMessage());
+        }
+    }
+}

src/test/java/nl/knaw/dans/lib/util/PingHealthCheckTest.java

@@ -0,0 +1,107 @@
+/*
+ * Copyright (C) 2021 DANS - Data Archiving and Networked Services (info@dans.knaw.nl)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package nl.knaw.dans.lib.util;
+
+import com.codahale.metrics.health.HealthCheck.Result;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.mockito.Mockito;
+
+import javax.ws.rs.client.Client;
+import javax.ws.rs.client.Invocation;
+import javax.ws.rs.client.WebTarget;
+import javax.ws.rs.core.Response;
+import java.net.URI;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+public class PingHealthCheckTest {
+    private Client httpClientMock;
+    private Response responseMock;
+
+    @BeforeEach
+    public void setUp() {
+        httpClientMock = mock(Client.class);
+        WebTarget webTargetMock = mock(WebTarget.class);
+        Invocation.Builder invocationBuilderMock = mock(Invocation.Builder.class);
+        responseMock = mock(Response.class);
+
+        when(httpClientMock.target(Mockito.any(URI.class))).thenReturn(webTargetMock);
+        when(webTargetMock.request(Mockito.anyString())).thenReturn(invocationBuilderMock);
+        when(invocationBuilderMock.get()).thenReturn(responseMock);
+    }
+
+    @Test
+    public void pong_result_should_result_in_health_check_passing() throws Exception {
+        // Given
+        when(responseMock.getStatus()).thenReturn(200);
+        when(responseMock.readEntity(String.class)).thenReturn("pong");
+        PingHealthCheck healthCheck = new PingHealthCheck("test", httpClientMock, new URI("http://localhost:8080/dummy"));
+
+        // When
+        Result result = healthCheck.check();
+
+        // Then
+        assertThat(result.isHealthy()).isTrue();
+        assertThat(result.getMessage()).isNull();
+    }
+
+    @Test
+    public void wrong_result_should_result_in_health_check_failing() throws Exception {
+        // Given
+        when(responseMock.getStatus()).thenReturn(200);
+        when(responseMock.readEntity(String.class)).thenReturn("wrong response");
+        PingHealthCheck healthCheck = new PingHealthCheck("test", httpClientMock, new URI("http://localhost:8080/dummy"));
+
+        // When
+        Result result = healthCheck.check();
+
+        // Then
+        assertThat(result.isHealthy()).isFalse();
+        assertThat(result.getMessage()).isEqualTo("test ping URL did not respond with 'pong'");
+    }
+
+    @Test
+    public void unexpected_status_should_result_in_health_check_failing() throws Exception {
+        // Given
+        when(responseMock.getStatus()).thenReturn(500);
+        when(responseMock.getStatusInfo()).thenReturn(Response.Status.INTERNAL_SERVER_ERROR);
+        PingHealthCheck healthCheck = new PingHealthCheck("test", httpClientMock, new URI("http://localhost:8080/dummy"));
+
+        // When
+        Result result = healthCheck.check();
+
+        // Then
+        assertThat(result.isHealthy()).isFalse();
+        assertThat(result.getMessage()).isEqualTo("Service responded with unexpected status: 500 Internal Server Error");
+    }
+
+    @Test
+    public void connection_error_should_result_in_health_check_failing() throws Exception {
+        // Given
+        when(httpClientMock.target(Mockito.any(URI.class))).thenThrow(new RuntimeException("Connection refused"));
+        PingHealthCheck healthCheck = new PingHealthCheck("test", httpClientMock, new URI("http://localhost:8080/dummy"));
+
+        // When
+        Result result = healthCheck.check();
+
+        // Then
+        assertThat(result.isHealthy()).isFalse();
+        assertThat(result.getMessage()).isEqualTo("Connection to test could not be established: Connection refused");
+    }
+}