MGM: add possibility to run a script after the slave to master transi…

…tion

mgm/QdbMaster.cc

@@ -42,6 +42,7 @@
 #include "common/plugin_manager/PluginManager.hh"
 #include "common/IntervalStopwatch.hh"
 #include <qclient/QClient.hh>
+#include "common/ShellCmd.hh"
 
 EOSMGMNAMESPACE_BEGIN
 
@@ -110,6 +111,7 @@ QdbMaster::BootNamespace()
   namespaceConfig["qdb_password"] = gOFS->mQdbPassword;
   namespaceConfig["qdb_flusher_md"] = SSTR(instance_id << "_md");
   namespaceConfig["qdb_flusher_quota"] = SSTR(instance_id << "_quota");
+
   if (!gOFS->mQClientFlusherType.empty()) {
     namespaceConfig["qclient_flusher_type"] = gOFS->mQClientFlusherType;
   }
@@ -118,7 +120,6 @@ QdbMaster::BootNamespace()
     namespaceConfig["qclient_rocksdb_options"] = gOFS->mQClientRocksDBOptions;
   }
 
-
   FillNsCacheConfig(gOFS->ConfEngine, namespaceConfig);
 
   if (!gOFS->namespaceGroup->initialize(&gOFS->eosViewRWMutex, namespaceConfig,
@@ -319,6 +320,7 @@ QdbMaster::Supervisor(ThreadAssistant& assistant) noexcept
 
           MasterLog(eos_log(LOG_ERR, "%s", "msg=\"acquired the master lease\""));
           SlaveToMaster();
+          PostSlaveToMaster(old_master_id, GetMasterId());
         }
       } else {
         std::string new_master_id = GetMasterId();
@@ -337,8 +339,7 @@ QdbMaster::Supervisor(ThreadAssistant& assistant) noexcept
             eos_static_info("%s", "msg=\"follow up master-to-slave transition\"");
             Access::SetMasterToSlaveRules(new_master_id);
             gOFS->mTracker.SetAcceptingRequests(true);
-          }
-          else {
+          } else {
             if (new_master_id == mIdentity) {
               if (mDoMasterDelay) {
                 if (mMasterDelayDeadline < std::chrono::system_clock::now()) {
@@ -367,6 +368,33 @@ QdbMaster::Supervisor(ThreadAssistant& assistant) noexcept
   RemoveStatusFile(EOSMGMMASTER_SUBSYS_RW_LOCKFILE);
 }
 
+//------------------------------------------------------------------------------
+// PostSlaveToMaster runs a custom hook. It is invoked after the SlaveToMaster
+// transition. It only runs if configured in the mgmofs.postslavetomaster option.
+//------------------------------------------------------------------------------
+void QdbMaster::PostSlaveToMaster(std::string old_master,
+                                  std::string new_master)
+{
+  if (gOFS->mPostSlaveToMaster.length() == 0) {
+    return;
+  }
+
+  eos_static_info("msg=\"running post slave to master script\" path=\"%s\"",
+                  gOFS->mPostSlaveToMaster.c_str());
+  std::string script = std::string(gOFS->mPostSlaveToMaster.c_str())
+                       + " '" + old_master + "'"
+                       + " '" + new_master + "'";
+  eos::common::ShellCmd cmd(script);
+  auto status = cmd.wait(POST_SLAVE_TO_MASTER_TIMEOUT);
+
+  if (status.exit_code) {
+    eos_static_warning("msg=\"post slave to master script failed\" script=\"%s\" retcode=%d",
+                       script, status.exit_code);
+  } else {
+    eos_static_info("msg=\"post slave to master script run successfully\"");
+  }
+}
+
 //------------------------------------------------------------------------------
 // Slave to master transition
 //------------------------------------------------------------------------------

mgm/QdbMaster.hh

@@ -37,6 +37,8 @@ class QClient;
 
 EOSMGMNAMESPACE_BEGIN
 
+#define POST_SLAVE_TO_MASTER_TIMEOUT 60
+
 //------------------------------------------------------------------------------
 //! Class IMaster
 //------------------------------------------------------------------------------
@@ -214,6 +216,11 @@ private:
   //----------------------------------------------------------------------------
   void SlaveToMaster();
 
+  //----------------------------------------------------------------------------
+  //! Run a post slave to master hook, if configured
+  //----------------------------------------------------------------------------
+  void PostSlaveToMaster(std::string old_master, std::string new_master);
+
   //----------------------------------------------------------------------------
   //! Master to slave transition
   //----------------------------------------------------------------------------

mgm/XrdMgmOfs.hh

@@ -830,8 +830,8 @@ public:
   //! container and the file individually before checking their access with the
   //! AccessChecker.
   //----------------------------------------------------------------------------
-   int _access(const char*, int mode, XrdOucErrInfo&,
-               eos::common::VirtualIdentity& vid, const char*);
+  int _access(const char*, int mode, XrdOucErrInfo&,
+              eos::common::VirtualIdentity& vid, const char*);
 
   //----------------------------------------------------------------------------
   //! @brief define access permissions for files/directories
@@ -1759,6 +1759,8 @@ public:
   XrdOucString MgmAuthDir; ///< Directory containing exported authentication token
   XrdOucString ManagerId; ///< manager id in <host>:<port> format
   XrdOucString ManagerIp; ///< manager ip in <xxx.yyy.zzz.vvv> format
+  XrdOucString
+  mPostSlaveToMaster; ///< Path of the script running after the Slave to Master transition
   int ManagerPort; ///< manager port as number e.g. 1094
   uint16_t XrdHttpPort; ///< The port on which the XrdHttp server is running
   std::string
@@ -1795,8 +1797,10 @@ public:
   bool mAuthorize; ///< Determine if the authorization should be applied or not
   std::string mAuthLib; ///< Path to authorization library
   bool mTapeEnabled; ///< True if support for tape is enabled
-  std::string mPrepareDestSpace; ///< Space to be used when retrieving files from tape
-  unsigned int mReqIdMax; ///< Maximum number of request IDs on a single retrieving file
+  std::string
+  mPrepareDestSpace; ///< Space to be used when retrieving files from tape
+  unsigned int
+  mReqIdMax; ///< Maximum number of request IDs on a single retrieving file
   //!  Acts only as a redirector, disables many components in the MGM
   bool MgmRedirector;
   //! Writes error log with cluster wide collected errors in

mgm/XrdMgmOfsConfigure.cc

@@ -1067,6 +1067,16 @@ XrdMgmOfs::Configure(XrdSysError& Eroute)
           }
         }
 
+        if (!strcmp("postslavetomaster", var)) {
+          if (!(val = Config.GetWord())) {
+            Eroute.Emsg("Config", "argument for postslavetomaster invalid.");
+            NoGo = 1;
+          } else {
+            Eroute.Say("=====> mgmofs.postslavetomaster: ", val, "");
+            mPostSlaveToMaster = val;
+          }
+        }
+
         if (!strcmp("protowfendpoint", var)) {
           val = Config.GetWord();
 

misc/etc/eos/config/mgm/mgm

@@ -54,6 +54,9 @@ mgmofs.autoloadconfig default
 # QoS configuration file
 mgmofs.qoscfg /var/eos/qos/qos.conf
 
+# Post slave to master transition script
+# mgmofs.postslavetomaster /usr/bin/true
+
 #-------------------------------------------------------------------------------
 # Configuration for the authentication plugin EosAuth
 #-------------------------------------------------------------------------------