Add HeartBeatService and HeartBeatController (#244)

pom.xml

@@ -127,12 +127,6 @@
             <version>2.10.1</version>
         </dependency>
 
-        <!-- PROMETHEUS -->
-        <dependency>
-            <groupId>io.micrometer</groupId>
-            <artifactId>micrometer-registry-prometheus</artifactId>
-        </dependency>
-
         <!-- JAXB -->
         <dependency>
             <groupId>jakarta.xml.bind</groupId>
@@ -164,6 +158,16 @@
             <version>8.5.10</version>
         </dependency>
 
+        <!-- MICROMEETER -->
+        <dependency>
+            <groupId>io.micrometer</groupId>
+            <artifactId>micrometer-core</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.micrometer</groupId>
+            <artifactId>micrometer-registry-prometheus</artifactId>
+        </dependency>
+
     </dependencies>
 
     <build>

src/main/java/de/app/fivegla/business/HeartBeatService.java

@@ -0,0 +1,41 @@
+package de.app.fivegla.business;
+
+import io.micrometer.core.instrument.Gauge;
+import io.micrometer.core.instrument.MeterRegistry;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.stereotype.Service;
+
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.AtomicLong;
+
+/**
+ * The HeartBeatService class provides functionality to register heartbeats.
+ */
+@Slf4j
+@Service
+@RequiredArgsConstructor
+public class HeartBeatService {
+
+    private final MeterRegistry meterRegistry;
+    private final ConcurrentHashMap<String, AtomicLong> lastHeartbeatTimestamps = new ConcurrentHashMap<>();
+
+    /**
+     * Register a heartbeat using Micrometer.
+     */
+    public void registerHeartBeat(String id) {
+        log.info("Registering heartbeat using Micrometer for sensor id: {}", id);
+        var counter = meterRegistry.counter("heartbeat", "id", id);
+        counter.increment();
+
+        lastHeartbeatTimestamps.computeIfAbsent(id, key -> {
+            AtomicLong timestamp = new AtomicLong();
+            Gauge.builder("heartbeat.lastTimestamp", timestamp, AtomicLong::get)
+                    .description("The timestamp of the last heartbeat for sensor id: " + id)
+                    .tags("sensorId", id)
+                    .register(meterRegistry);
+            return timestamp;
+        }).set(System.currentTimeMillis());
+    }
+
+}

src/main/java/de/app/fivegla/controller/api/BaseMappings.java

@@ -23,6 +23,7 @@ public class BaseMappings {
     public static final String MAINTENANCE = SECURED_BY_API_KEY + "/maintenance";
     public static final String INFO = SECURED_BY_API_KEY + "/info";
     public static final String TENANT = SECURED_BY_API_KEY + "/tenant";
+    public static final String HEARTBEAT = SECURED_BY_API_KEY + "/heartbeat";
 
     // SECURED_BY_TENANT
 

src/main/java/de/app/fivegla/controller/global/HeartBeatController.java

@@ -0,0 +1,46 @@
+package de.app.fivegla.controller.global;
+
+import de.app.fivegla.business.HeartBeatService;
+import de.app.fivegla.config.security.marker.ApiKeyApiAccess;
+import de.app.fivegla.controller.api.BaseMappings;
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.media.Schema;
+import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+/**
+ * The HeartBeatController class handles heartbeat-related operations.
+ * It provides a method to register a heartbeat.
+ * <p>
+ * This controller is mapped to the /heartbeat endpoint.
+ */
+@Slf4j
+@RestController
+@RequestMapping(BaseMappings.HEARTBEAT)
+@RequiredArgsConstructor
+public class HeartBeatController implements ApiKeyApiAccess {
+
+    private final HeartBeatService heartBeatService;
+
+    @Operation(
+            operationId = "heartbeat",
+            description = "Heartbeat endpoint.",
+            tags = BaseMappings.HEARTBEAT
+    )
+    @ApiResponse(
+            responseCode = "200",
+            description = "The heartbeat was successful."
+    )
+    @PostMapping("/{id}")
+    public ResponseEntity<Void> heartBeat(@PathVariable @Schema(description = "The ID") String id) {
+        heartBeatService.registerHeartBeat(id);
+        return ResponseEntity.ok().build();
+    }
+
+}