From 59071ea15d2aacb69fcfc088f4996717cd2bfc73 Mon Sep 17 00:00:00 2001
From: Stefan Tatschner <stefan@rumpelsepp.org>
Date: Tue, 12 Jan 2021 22:38:53 +0100
Subject: cmd: Implement sd_notify() to notify systemd about readiness (#3963)

Issue: #3786
Based on Gaurav Dhameeja's work in #3908.
---
 cmd/notify_linux.go | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 cmd/notify_linux.go

(limited to 'cmd/notify_linux.go')

diff --git a/cmd/notify_linux.go b/cmd/notify_linux.go
new file mode 100644
index 0000000..924c00f
--- /dev/null
+++ b/cmd/notify_linux.go
@@ -0,0 +1,68 @@
+// Copyright 2015 Matthew Holt and The Caddy Authors
+//
+// 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 caddycmd
+
+import (
+	"io"
+	"net"
+	"os"
+	"strings"
+)
+
+// The documentation about this IPC protocol is available here:
+// https://www.freedesktop.org/software/systemd/man/sd_notify.html
+
+func sdNotify(path, payload string) error {
+	socketAddr := &net.UnixAddr{
+		Name: path,
+		Net:  "unixgram",
+	}
+
+	conn, err := net.DialUnix(socketAddr.Net, nil, socketAddr)
+	if err != nil {
+		return err
+	}
+	defer conn.Close()
+
+	if _, err := io.Copy(conn, strings.NewReader(payload)); err != nil {
+		return err
+	}
+	return nil
+}
+
+// notifyReadiness notifies systemd caddy that has finished its
+// initialization routines.
+func notifyReadiness() error {
+	val, ok := os.LookupEnv("NOTIFY_SOCKET")
+	if !ok || val == "" {
+		return nil
+	}
+	if err := sdNotify(val, "READY=1"); err != nil {
+		return err
+	}
+	return nil
+}
+
+// notifyReadiness notifies systemd that caddy is reloading its config.
+func notifyReloading() error {
+	val, ok := os.LookupEnv("NOTIFY_SOCKET")
+	if !ok || val == "" {
+		return nil
+	}
+	if err := sdNotify(val, "RELOADING=1"); err != nil {
+		return err
+	}
+	return nil
+}
-- 
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