From aabb92ef56c4faa8f05487e9fcdf83f1053f1a22 Mon Sep 17 00:00:00 2001
From: Deepak Kodihalli <dkodihal@in.ibm.com>
Date: Wed, 17 Oct 2018 05:03:20 -0500
Subject: phosphor-rsyslog-conf: react to hostname change

The rsyslog client caches the hostname when it starts up (hostname is
included in logs that are streamed out). If someone changes hostname via
REST API for example, the same won't reflect in rsyslog logs at the
server.

Listen to the hostname changed D-Bus signal from systemd, and restart
rsyslogd when this happens. This ensures logs are streamed out with the
updated hostname.

Change-Id: Ied2b401e621314ef7c25e97dc93f86a429fb4077
Signed-off-by: Deepak Kodihalli <dkodihal@in.ibm.com>
---
 phosphor-rsyslog-config/server-conf.hpp | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/phosphor-rsyslog-config/server-conf.hpp b/phosphor-rsyslog-config/server-conf.hpp
index edab113..8660416 100644
--- a/phosphor-rsyslog-config/server-conf.hpp
+++ b/phosphor-rsyslog-config/server-conf.hpp
@@ -14,6 +14,7 @@ namespace rsyslog_config
 using namespace phosphor::logging;
 using NetworkClient = sdbusplus::xyz::openbmc_project::Network::server::Client;
 using Iface = sdbusplus::server::object::object<NetworkClient>;
+namespace sdbusRule = sdbusplus::bus::match::rules;
 
 /** @class Server
  *  @brief Configuration for rsyslog server
@@ -40,7 +41,13 @@ class Server : public Iface
                const std::string& path,
                const char* filePath) :
             Iface(bus, path.c_str(), true),
-            configFilePath(filePath)
+            configFilePath(filePath),
+            hostnameChange(
+                bus,
+                sdbusRule::propertiesChanged(
+                    "/org/freedesktop/hostname1", "org.freedesktop.hostname1"),
+                std::bind(std::mem_fn(&Server::hostnameChanged),
+                    this, std::placeholders::_1))
         {
             try
             {
@@ -97,6 +104,16 @@ class Server : public Iface
         void restore(const char* filePath);
 
         std::string configFilePath{};
+
+        /** @brief React to hostname change
+         *  @param[in] msg - sdbusplus message
+         */
+        void hostnameChanged(sdbusplus::message::message& msg)
+        {
+            restart();
+        }
+
+        sdbusplus::bus::match_t hostnameChange;
 };
 
 } // namespace rsyslog_config
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