From 8d6e45331cb4ba86faaabfe7d1f9e7ccfd6e824d Mon Sep 17 00:00:00 2001
From: Anton Tananaev <anton.tananaev@gmail.com>
Date: Sat, 22 Feb 2020 16:59:43 -0800
Subject: Support health monitoring

---
 .../java/org/traccar/api/HealthCheckService.java   | 90 ++++++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 src/main/java/org/traccar/api/HealthCheckService.java

(limited to 'src/main/java/org/traccar/api/HealthCheckService.java')

diff --git a/src/main/java/org/traccar/api/HealthCheckService.java b/src/main/java/org/traccar/api/HealthCheckService.java
new file mode 100644
index 000000000..cd2856dfa
--- /dev/null
+++ b/src/main/java/org/traccar/api/HealthCheckService.java
@@ -0,0 +1,90 @@
+/*
+ * Copyright 2020 Anton Tananaev (anton@traccar.org)
+ *
+ * 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 org.traccar.api;
+
+import com.sun.jna.Library;
+import com.sun.jna.Native;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.traccar.Context;
+
+import java.util.TimerTask;
+
+public class HealthCheckService {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(HealthCheckService.class);
+
+    private SystemD systemD;
+
+    private boolean enabled;
+    private long period;
+
+    public HealthCheckService() {
+        if (Context.getConfig().getBoolean("web.healthCheck")
+                && System.getProperty("os.name").toLowerCase().startsWith("linux")) {
+            try {
+                systemD = Native.load("systemd", SystemD.class);
+                String watchdogTimer = System.getenv("WATCHDOG_USEC");
+                if (watchdogTimer != null && !watchdogTimer.isEmpty()) {
+                    period = Long.parseLong(watchdogTimer) / 1000 * 4 / 5;
+                }
+                if (period > 0) {
+                    LOGGER.info("Health check enabled with period {}", period);
+                    enabled = true;
+                }
+            } catch (UnsatisfiedLinkError e) {
+                LOGGER.warn("No systemd support", e);
+            }
+        }
+    }
+
+    public boolean isEnabled() {
+        return enabled;
+    }
+
+    public long getPeriod() {
+        return period;
+    }
+
+    private String getUrl() {
+        String address = Context.getConfig().getString("web.address", "localhost");
+        int port = Context.getConfig().getInteger("web.port", 8082);
+        return "http://" + address + ":" + port + "/api/server";
+    }
+
+    public TimerTask createTask() {
+        return new TimerTask() {
+            @Override
+            public void run() {
+                LOGGER.debug("Health check running");
+                int status = Context.getClient().target(getUrl()).request().get().getStatus();
+                if (status == 200) {
+                    int result = systemD.sd_notify(0, "WATCHDOG=1");
+                    if (result < 0) {
+                        LOGGER.warn("Health check notify error {}", result);
+                    }
+                } else {
+                    LOGGER.warn("Health check failed with status {}", status);
+                }
+            }
+        };
+    }
+
+    interface SystemD extends Library {
+        int sd_notify(int unset_environment, String state);
+    }
+
+}
-- 
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