add healthcheck for forward http connection

Author: CalebSLane

src/main/java/org/itech/ahb/health/HTTPForwardServerHealthIndicator.java

@@ -0,0 +1,66 @@
+package org.itech.ahb.health;
+
+import java.io.IOException;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpRequest.Builder;
+import java.net.http.HttpResponse;
+import java.util.Base64;
+import lombok.extern.slf4j.Slf4j;
+import org.itech.ahb.config.properties.HTTPForwardServerConfigurationProperties;
+import org.springframework.boot.actuate.autoconfigure.health.ConditionalOnEnabledHealthIndicator;
+import org.springframework.boot.actuate.health.Health;
+import org.springframework.boot.actuate.health.HealthIndicator;
+import org.springframework.stereotype.Component;
+
+@Component("httpforward")
+@ConditionalOnEnabledHealthIndicator("httpforward")
+@Slf4j
+public class HTTPForwardServerHealthIndicator implements HealthIndicator {
+
+  private final HTTPForwardServerConfigurationProperties properties;
+
+  public HTTPForwardServerHealthIndicator(HTTPForwardServerConfigurationProperties properties) {
+    this.properties = properties;
+  }
+
+  @Override
+  public Health health() {
+    if (properties.getHealthUri() == null) {
+      return Health.unknown().build();
+    }
+    HttpClient client = HttpClient.newHttpClient();
+    log.debug("creating request to test forward http server at " + properties.getHealthUri().toString());
+    Builder requestBuilder = HttpRequest.newBuilder()
+      .method(properties.getHealthMethod().toString(), HttpRequest.BodyPublishers.ofString(properties.getHealthBody()))
+      .uri(properties.getHealthUri());
+    if (!(properties.getUsername() == null || properties.getUsername().equals(""))) {
+      log.debug(
+        "using username '" +
+        properties.getUsername() +
+        "' to test forward http server at " +
+        properties.getUri().toString().toString()
+      );
+      requestBuilder.header(
+        "Authorization",
+        "Basic " +
+        Base64.getEncoder()
+          .encodeToString((properties.getUsername() + ":" + new String(properties.getPassword())).getBytes())
+      );
+    }
+    HttpRequest request = requestBuilder.build();
+
+    try {
+      log.debug("testing forward http server at " + properties.getHealthUri().toString());
+      HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
+      if (response.statusCode() == 200) {
+        log.debug("testing forward http server at " + properties.getHealthUri().toString() + " success");
+        return Health.up().build();
+      }
+    } catch (IOException | InterruptedException e) {
+      log.debug("error occurred communicating with http server at " + properties.getHealthUri().toString(), e);
+    }
+    log.debug("testing forward http server at " + properties.getHealthUri().toString() + " failure");
+    return Health.down().build();
+  }
+}

src/main/resources/application-dev.yml

@@ -1,5 +1,9 @@
 server:
   port: 8443
+management:
+  endpoint:
+    health:
+      show-details: always
 #  ssl:
 #    enabled: true
 #    keyStoreType: ${server.ssl.keyStoreType}