Support external log rotation tools via SIGUSR2

include/tscore/Diags.h

@@ -219,6 +219,7 @@ class Diags
   bool setup_diagslog(BaseLogFile *blf);
   void config_roll_diagslog(RollingEnabledValues re, int ri, int rs);
   void config_roll_outputlog(RollingEnabledValues re, int ri, int rs);
+  bool reseat_diagslog();
   bool should_roll_diagslog();
   bool should_roll_outputlog();
 

proxy/logging/Log.cc

@@ -140,6 +140,12 @@ Log::change_configuration()
   Debug("log-config", "... new configuration in place");
 }
 
+void
+Log::reopen_moved_log_files()
+{
+  Log::config->log_object_manager.reopen_moved_log_files();
+}
+
 /*-------------------------------------------------------------------------
   PERIODIC EVENTS
 

proxy/logging/Log.h

@@ -200,6 +200,14 @@ class Log
 
   // reconfiguration stuff
   static void change_configuration();
+
+  /** Check each log file path to see whether it exists and re-open if not.
+   *
+   * This is called when an external log rotation entity has moved log files to
+   * rolled names. This checks whether the original log file exists and, if
+   * not, closes the file descriptor and re-opens the file.
+   */
+  static void reopen_moved_log_files();
   static int handle_logging_mode_change(const char *name, RecDataT data_type, RecData data, void *cookie);
   static int handle_periodic_tasks_int_change(const char *name, RecDataT data_type, RecData data, void *cookie);
 

proxy/logging/LogFile.cc

@@ -391,6 +391,35 @@ LogFile::roll(long interval_start, long interval_end, bool reopen_after_rolling)
   return 0;
 }
 
+/*-------------------------------------------------------------------------
+  LogFile::reopen_if_moved
+
+  Check whether the file at the log's filename exists and, if not, close
+  the current file descriptor and reopen it. This function can be used to
+  facilitate external log rotation mechanisms which will move the original
+  file to a rolled filename. Logging will happen to that same file
+  descriptor until this function is called, at which point the non-existent
+  original file will be detected, the file descriptor will be closed, and
+  the log file will be re-opened.
+
+  Returns True if the file was re-opened, false otherwise.
+  -------------------------------------------------------------------------*/
+bool
+LogFile::reopen_if_moved()
+{
+  if (!m_name) {
+    return false;
+  }
+  if (LogFile::exists(m_name)) {
+    return false;
+  }
+
+  // Both of the following log if there are problems.
+  close_file();
+  open_file();
+  return true;
+}
+
 /*-------------------------------------------------------------------------
   LogFile::preproc_and_try_delete
 

proxy/logging/LogFile.h

@@ -61,6 +61,13 @@ class LogFile : public LogBufferSink, public RefCountObj
   bool trim_rolled(size_t rolling_max_count);
   int roll(long interval_start, long interval_end, bool reopen_after_rolling = false);
 
+  /** Check whether the file at the log's filename exists and, if not, close
+   * the current file descriptor and reopen it.
+   *
+   * @return True if the file was re-opened, false otherwise.
+   */
+  bool reopen_if_moved();
+
   const char *
   get_name() const
   {

proxy/logging/LogObject.cc

@@ -1241,6 +1241,22 @@ LogObjectManager::roll_files(long time_now)
   return num_rolled;
 }
 
+void
+LogObjectManager::reopen_moved_log_files()
+{
+  for (auto &_object : this->_objects) {
+    _object->m_logFile->reopen_if_moved();
+  }
+
+  ACQUIRE_API_MUTEX("A LogObjectManager::reopen_moved_log_files");
+
+  for (auto &_APIobject : this->_APIobjects) {
+    _APIobject->m_logFile->reopen_if_moved();
+  }
+
+  RELEASE_API_MUTEX("R LogObjectManager::reopen_moved_log_files");
+}
+
 void
 LogObjectManager::display(FILE *str)
 {

proxy/logging/LogObject.h

@@ -388,6 +388,7 @@ class LogObjectManager
   void check_buffer_expiration(long time_now);
 
   unsigned roll_files(long time_now);
+  void reopen_moved_log_files();
 
   int log(LogAccess *lad);
   void display(FILE *str = stdout);

src/traffic_manager/traffic_manager.cc

@@ -83,14 +83,14 @@ extern "C" int getpwnam_r(const char *name, struct passwd *result, char *buffer,
 
 static AppVersionInfo appVersionInfo; // Build info for this application
 
-static inkcoreapi DiagsConfig *diagsConfig;
-static char debug_tags[1024]  = "";
-static char action_tags[1024] = "";
-static int proxy_off          = false;
-static int listen_off         = false;
-static char bind_stdout[512]  = "";
-static char bind_stderr[512]  = "";
-static const char *mgmt_path  = nullptr;
+static inkcoreapi DiagsConfig *diagsConfig = nullptr;
+static char debug_tags[1024]               = "";
+static char action_tags[1024]              = "";
+static int proxy_off                       = false;
+static int listen_off                      = false;
+static char bind_stdout[512]               = "";
+static char bind_stderr[512]               = "";
+static const char *mgmt_path               = nullptr;
 
 // By default, set the current directory as base
 static const char *recs_conf = ts::filename::RECORDS;
@@ -923,6 +923,22 @@ SignalHandler(int sig)
     return;
   }
 
+  if (sig == SIGUSR2) {
+    fprintf(stderr, "[TrafficManager] ==> received SIGUSR2, rotating the logs.\n");
+    mgmt_log("[TrafficManager] ==> received SIGUSR2, rotating the logs.\n");
+    if (lmgmt && lmgmt->watched_process_pid != -1) {
+      kill(lmgmt->watched_process_pid, sig);
+    }
+    diags->set_std_output(StdStream::STDOUT, bind_stdout);
+    diags->set_std_output(StdStream::STDERR, bind_stderr);
+    if (diags->reseat_diagslog()) {
+      Note("Reseated %s", DIAGS_LOG_FILENAME);
+    } else {
+      Note("Could not reseat %s", DIAGS_LOG_FILENAME);
+    }
+    return;
+  }
+
   fprintf(stderr, "[TrafficManager] ==> Cleaning up and reissuing signal #%d\n", sig);
   mgmt_log("[TrafficManager] ==> Cleaning up and reissuing signal #%d\n", sig);
 

src/traffic_server/traffic_server.cc

@@ -281,10 +281,16 @@ class SignalContinuation : public Continuation
       signal_received[SIGUSR2] = false;
 
       Debug("log", "received SIGUSR2, reloading traffic.out");
-
       // reload output logfile (file is usually called traffic.out)
       diags->set_std_output(StdStream::STDOUT, bind_stdout);
       diags->set_std_output(StdStream::STDERR, bind_stderr);
+      if (diags->reseat_diagslog()) {
+        Note("Reseated %s", DIAGS_LOG_FILENAME);
+      } else {
+        Note("Could not reseat %s", DIAGS_LOG_FILENAME);
+      }
+      // Reload any of the other moved log files (such as the ones in logging.yaml).
+      Log::reopen_moved_log_files();
     }
 
     if (signal_received[SIGTERM] || signal_received[SIGINT]) {

src/tscore/Diags.cc

@@ -516,6 +516,40 @@ Diags::config_roll_outputlog(RollingEnabledValues re, int ri, int rs)
   outputlog_rolling_size     = rs;
 }
 
+/*
+ * Update diags_log to use the underlying file on disk.
+ *
+ * This function will replace the current BaseLogFile object with a new one, as
+ * each BaseLogFile object logically represents one file on disk. It can be
+ * used when we want to re-open the log file if the initial one was moved.
+ *
+ * Note that, however, cross process race conditions may still exist,
+ * especially with the metafile, and further work with flock() for fcntl() may
+ * still need to be done.
+ *
+ * Returns true if the log was reseated, false otherwise.
+ */
+bool
+Diags::reseat_diagslog()
+{
+  if (diags_log == nullptr || !diags_log->is_init()) {
+    return false;
+  }
+  fflush(diags_log->m_fp);
+  char *oldname = ats_strdup(diags_log->get_name());
+  log_log_trace("in %s for diags.log, oldname=%s\n", __func__, oldname);
+  BaseLogFile *n = new BaseLogFile(oldname);
+  if (setup_diagslog(n)) {
+    BaseLogFile *old_diags = diags_log;
+    lock();
+    diags_log = n;
+    unlock();
+    delete old_diags;
+  }
+  ats_free(oldname);
+  return true;
+}
+
 /*
  * Checks diags_log 's underlying file on disk and see if it needs to be rolled,
  * and does so if necessary.

tests/gold_tests/autest-site/trafficserver.test.ext

@@ -193,6 +193,11 @@ def MakeATSProcess(obj, name, command='traffic_server', select_ports=True,
     p.Disk.diags_log.Content += Testers.ExcludesExpression(
         "FATAL:", "diags.log should not contain errors")
 
+    if command == "traffic_manager":
+        fname = "manager.log"
+        tmpname = os.path.join(log_dir, fname)
+        p.Disk.File(tmpname, id=make_id(fname))
+
     # config files
     def MakeConfigFile(self, fname):
         tmpname = os.path.join(config_dir, fname)