Added health endpoint

src/main/java/com/litoralregas/openvpn/health/HealthController.java

@@ -0,0 +1,21 @@
+package com.litoralregas.openvpn.health;
+
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("/api/health")
+public class HealthController {
+
+    private final OpenVpnHealthService openVpnHealthService;
+
+    public HealthController(OpenVpnHealthService openVpnHealthService) {
+        this.openVpnHealthService = openVpnHealthService;
+    }
+
+    @GetMapping("/openvpn")
+    public OpenVpnHealthResponse getOpenVpnHealth() {
+        return openVpnHealthService.checkHealth();
+    }
+}

src/main/java/com/litoralregas/openvpn/health/OpenVpnHealthResponse.java

@@ -0,0 +1,9 @@
+package com.litoralregas.openvpn.health;
+
+import java.util.List;
+
+public record OpenVpnHealthResponse(
+        String status,
+        List<OpenVpnServerHealth> servers
+) {
+}

src/main/java/com/litoralregas/openvpn/health/OpenVpnHealthService.java

@@ -0,0 +1,114 @@
+package com.litoralregas.openvpn.health;
+
+import com.litoralregas.openvpn.ssh.SshCommandResult;
+import com.litoralregas.openvpn.ssh.SshService;
+import org.springframework.stereotype.Service;
+
+import java.time.Instant;
+import java.util.List;
+
+@Service
+public class OpenVpnHealthService {
+
+    private final SshService sshService;
+
+    public OpenVpnHealthService(SshService sshService) {
+        this.sshService = sshService;
+    }
+
+    public OpenVpnHealthResponse checkHealth() {
+        OpenVpnServerHealth serverHealth = checkConfiguredVps();
+
+        String overallStatus;
+
+        if (!serverHealth.reachable()) {
+            overallStatus = "OFFLINE";
+        } else if (!serverHealth.openvpnServiceActive()) {
+            overallStatus = "DEGRADED";
+        } else {
+            overallStatus = "ONLINE";
+        }
+
+        return new OpenVpnHealthResponse(
+                overallStatus,
+                List.of(serverHealth)
+        );
+    }
+
+    private OpenVpnServerHealth checkConfiguredVps() {
+        String checkedAt = Instant.now().toString();
+
+        SshCommandResult serviceResult = sshService.executeOnConfiguredVps(
+                """
+                if systemctl is-active --quiet openvpn-server@server; then
+                  echo ACTIVE
+                elif systemctl is-active --quiet openvpn@server; then
+                  echo ACTIVE
+                elif systemctl is-active --quiet openvpn; then
+                  echo ACTIVE
+                else
+                  echo INACTIVE
+                  systemctl list-units --type=service --all | grep -i openvpn || true
+                fi
+                """
+        );
+
+        boolean reachable = serviceResult.exitCode() != -1;
+        boolean active = serviceResult.stdout().contains("ACTIVE");
+
+        Integer activeClients = null;
+
+        if (reachable && active) {
+            activeClients = getActiveClientCount();
+        }
+
+        String error = null;
+
+        if (!reachable) {
+            error = serviceResult.stderr();
+        } else if (!active) {
+            error = cleanOutput(serviceResult.stdout() + "\n" + serviceResult.stderr());
+        }
+
+        return new OpenVpnServerHealth(
+                "Configured VPS",
+                reachable,
+                active,
+                activeClients,
+                checkedAt,
+                error
+        );
+    }
+
+    private Integer getActiveClientCount() {
+        SshCommandResult result = sshService.executeOnConfiguredVps(
+                """
+                if [ -f /var/log/openvpn/status.log ]; then
+                  grep -A 100 "Common Name" /var/log/openvpn/status.log | grep -v "Common Name" | grep -v "ROUTING TABLE" | grep -v "GLOBAL STATS" | grep -v "^$" | wc -l
+                elif [ -f /run/openvpn-server/status-server.log ]; then
+                  grep -A 100 "Common Name" /run/openvpn-server/status-server.log | grep -v "Common Name" | grep -v "ROUTING TABLE" | grep -v "GLOBAL STATS" | grep -v "^$" | wc -l
+                else
+                  echo 0
+                fi
+                """
+        );
+
+        if (result.exitCode() != 0) {
+            return null;
+        }
+
+        try {
+            return Integer.parseInt(result.stdout().trim());
+        } catch (NumberFormatException e) {
+            return null;
+        }
+    }
+
+    private String cleanOutput(String value) {
+        if (value == null || value.isBlank()) {
+            return null;
+        }
+
+        return value.trim();
+    }
+}

src/main/java/com/litoralregas/openvpn/health/OpenVpnServerHealth.java

@@ -0,0 +1,11 @@
+package com.litoralregas.openvpn.health;
+
+public record OpenVpnServerHealth(
+        String name,
+        boolean reachable,
+        boolean openvpnServiceActive,
+        Integer activeClients,
+        String checkedAt,
+        String error
+) {
+}