repmgrd: always reopen log file after receiving SIGHUP

For whatever reason, since at least repmgr 2.0 the log file was only
ever reopened if a configuration file change took place.

GitHub #485.

HISTORY

@@ -1,3 +1,8 @@
+
+4.1.1   2018-??-??
+        repmgrd: ensure that sending SIGHUP always results in the log file
+          being reopened; GitHub #485 (Ian)
+
 4.1.0   2018-07-31
         repmgr: change default log_level to INFO, add documentation; GitHub #470 (Ian)
         repmgr: add "--missing-slots" check to "repmgr node check" (Ian)

doc/appendix-release-notes.sgml

@@ -15,6 +15,34 @@
     See also: <xref linkend="upgrading-repmgr">
   </para>
 
+  <sect1 id="release-4.1.1">
+    <title>Release 4.1.1</title>
+    <para><emphasis>??? ??? ??, 2018</emphasis></para>
+    <para>
+    </para>
+
+    <sect2>
+      <title>repmgrd enhancements</title>
+      <para>
+        <itemizedlist>
+
+          <listitem>
+            <para>
+              <application>repmgrd</application>: always reopen the log file after
+              receiving <literal>SIGHUP</literal>. Previously this only happened if
+              a configuration file change was detected.
+              (GitHub #485).
+            </para>
+          </listitem>
+        </itemizedlist>
+      </para>
+    </sect2>
+
+
+  </sect1>
+
+
+
   <sect1 id="release-4.1.0">
     <title>Release 4.1.0</title>
     <para><emphasis>Tue July 31, 2018</emphasis></para>

doc/repmgrd-configuration.sgml

@@ -323,11 +323,16 @@ REPMGRD_ENABLED=no
      <secondary>repmgrd</secondary>
    </indexterm>
 
+   <indexterm>
+     <primary>repmgrd</primary>
+     <secondary>log rotation</secondary>
+   </indexterm>
+
   <title>repmgrd log rotation</title>
   <para>
    To ensure the current <application>repmgrd</application> logfile
    (specified in <filename>repmgr.conf</filename> with the parameter
-   <option>log_file</option> does not grow indefinitely, configure your
+   <option>log_file</option>) does not grow indefinitely, configure your
    system's <command>logrotate</command> to regularly rotate it.
   </para>
   <para>
@@ -340,33 +345,12 @@ REPMGRD_ENABLED=no
         rotate 52
         maxsize 100M
         weekly
-        copytruncate
+        create 0600 postgres postgres
+        postrotate
+            /usr/bin/killall -HUP repmgrd
+        endscript
     }</programlisting>
   </para>
 
-  <note>
-    <para>
-      Currently <application>repmgrd</application> will not reopen the log
-      file unless the configuration is reloaded via <literal>SIGHUP</literal>
-      <emphasis>and</emphasis> the configuration changes.
-    </para>
-    <para>
-      Therefore it's recommended to use <literal>copytruncate</literal> when
-      rotating logs, so that the contents of the existing file are rotated out
-      by creating a copy, then truncating the original file, which
-      <application>repmgrd</application> still holds open.
-    </para>
-    <para>
-      Note that any logging data written in the (short) timespan after the existing file
-      is copied, but before it is truncated, will be lost; see the
-      <ulink url="https://linux.die.net/man/8/logrotate">logrotate documentation</ulink>.
-    </para>
-    <para>
-      This restriction may be lifted in a future &repmgr; version by providing a
-      signal which causes <application>repmgrd</application> to reopen the log file,
-      and which can be sent from <command>logrotate</command> via a <command>postrotate</command>
-      script.
-    </para>
-  </note>
  </sect1>
 </chapter>

repmgrd-physical.c

@@ -2936,18 +2936,21 @@ handle_sighup(PGconn *conn)
 	{
 		close_connection(&conn);
 		conn = establish_db_connection(config_file_options.conninfo, true);
+	}
 
-		if (*config_file_options.log_file)
+	if (*config_file_options.log_file)
+	{
+		FILE	   *fd;
+
+		log_debug("reopening %s", config_file_options.log_file);
+
+		fd = freopen(config_file_options.log_file, "a", stderr);
+		if (fd == NULL)
 		{
-			FILE	   *fd;
+			fprintf(stderr, "error reopening stderr to \"%s\": %s",
-
+					config_file_options.log_file, strerror(errno));
-			fd = freopen(config_file_options.log_file, "a", stderr);
-			if (fd == NULL)
-			{
-				fprintf(stderr, "error reopening stderr to \"%s\": %s",
-						config_file_options.log_file, strerror(errno));
-			}
 		}
 	}
+
 	got_SIGHUP = false;
 }