systemd notify

src/one/nio/os/systemd/SystemdNotify.java

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+/*
+ * Copyright 2020 Odnoklassniki Ltd, Mail.Ru Group
+ *
+ * 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 one.nio.os.systemd;
+
+import one.nio.net.Socket;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+
+/**
+ * Notify service manager about start-up completion and other service status changes
+ *
+ * @see <a href="https://www.freedesktop.org/software/systemd/man/sd_notify.html">man:sd_notify(3)</a>
+ */
+public class SystemdNotify {
+    private static final Log log = LogFactory.getLog(SystemdNotify.class);
+
+    public static final String NOTIFY_SOCKET_ENV   = "NOTIFY_SOCKET";
+    public static final String READY               = "READY=1";
+    public static final String RELOADING           = "RELOADING=1";
+    public static final String STOPPING            = "STOPPING=1";
+    public static final String STATUS              = "STATUS=%s";
+    public static final String ERRNO               = "ERRNO=%d";
+    public static final String BUSERROR            = "BUSERROR=%s";
+    public static final String MAINPID             = "MAINPID=%d";
+    public static final String WATCHDOG            = "WATCHDOG=1";
+    public static final String WATCHDOG_TRIGGER    = "WATCHDOG=trigger";
+    public static final String WATCHDOG_USEC       = "WATCHDOG_USEC=%d";
+    public static final String EXTEND_TIMEOUT_USEC = "EXTEND_TIMEOUT_USEC=%d";
+
+    public static void notify(String state) throws IOException {
+        String notifySocket = System.getenv(NOTIFY_SOCKET_ENV);
+        if (notifySocket == null) {
+            if (log.isDebugEnabled()) {
+                log.debug(NOTIFY_SOCKET_ENV + " environment variable is not defined");
+            }
+            return;
+        }
+
+        try (Socket socket = Socket.createUnixSocket()) {
+            if (log.isDebugEnabled()) {
+                log.debug(String.format("send '%s' to notify socket '%s'", state, notifySocket));
+            }
+            ByteBuffer buffer = ByteBuffer.wrap(state.getBytes(StandardCharsets.UTF_8));
+            socket.send(buffer, 0, notifySocket, Socket.NO_PORT);
+        }
+    }
+
+    public static void ready() throws IOException {
+        notify(READY);
+    }
+
+    public static void reloading() throws IOException {
+        notify(RELOADING);
+    }
+
+    public static void stopping() throws IOException {
+        notify(STOPPING);
+    }
+
+    public static void status(String text) throws IOException {
+        notify(String.format(STATUS, text));
+    }
+
+    public static void errno(int errno) throws IOException {
+        notify(String.format(ERRNO, errno));
+    }
+
+    public static void busError(String error) throws IOException {
+        notify(String.format(BUSERROR, error));
+    }
+
+    public static void mainPid(int pid) throws IOException {
+        notify(String.format(MAINPID, pid));
+    }
+
+    public static void watchdog() throws IOException {
+        notify(WATCHDOG);
+    }
+
+    public static void watchdogTrigger() throws IOException {
+        notify(WATCHDOG_TRIGGER);
+    }
+
+    public static void watchdogUsec(int usec) throws IOException {
+        notify(String.format(WATCHDOG_USEC, usec));
+    }
+
+    public static void extendTimeoutUsec(int usec) throws IOException {
+        notify(String.format(EXTEND_TIMEOUT_USEC, usec));
+    }
+}