[7X] Skip ssh if segments are on the same host with coordinator. (#16…

…812)

We can skip ssh connections if segments are on the same host with the
coordinator. We can save some time when executing commands. E.g., with
this patch, we don't ssh connection when creating the demo cluster and
the creation time can be reduced from 18s to 10s on my laptop. Besides,
we can skip setting up ssh keys for deploying the demo cluster.

gpMgmt/bin/gppylib/commands/base.py

@@ -22,6 +22,7 @@
 
 import os
 import signal
+import socket
 import subprocess
 import sys
 import time
@@ -502,14 +503,19 @@ def execute(self, cmd, pickled=False, start_new_session=False):
 
         # Escape \ and  " for remote execution
         cmd.cmdStr = cmd.cmdStr.replace('\\','\\\\').replace('"', '\\"')
-        cmd.cmdStr = "ssh -o StrictHostKeyChecking=no -o ServerAliveInterval=60 " \
-                     "{targethost} \"{gphome} {cmdstr}\"".format(targethost=self.targetHost,
-                                                                 gphome=". %s/greenplum_path.sh;" % self.gphome,
-                                                                 cmdstr=cmd.cmdStr)
+
+        localhost = socket.gethostname()
+        if localhost != self.targetHost:
+            cmd.cmdStr = "ssh -o StrictHostKeyChecking=no -o ServerAliveInterval=60 " \
+                         "{targethost} \"{gphome} {cmdstr}\"".format(targethost=self.targetHost,
+                                                                     gphome=". %s/greenplum_path.sh;" % self.gphome,
+                                                                     cmdstr=cmd.cmdStr)
+        else:
+            cmd.cmdStr = "bash -c \"{gphome} {cmdstr}\"".format(gphome=". %s/greenplum_path.sh;" % self.gphome,
+                                                                cmdstr=cmd.cmdStr)
         LocalExecutionContext.execute(self, cmd, pickled=pickled, start_new_session=start_new_session)
         if (cmd.get_stderr().startswith('ssh_exchange_identification: Connection closed by remote host')):
             self.__retry(cmd, 0, pickled)
-        pass
 
     def __retry(self, cmd, count, pickled):
         if count == SSH_MAX_RETRY:

gpMgmt/bin/gppylib/commands/gp.py

@@ -1651,11 +1651,13 @@ def list_addrs(hostname=None, include_loopback=False):
         cmd = ["echo 'START_CMD_OUTPUT'; %s/libexec/ifaddrs" % GPHOME]
         if not include_loopback:
             cmd.append('--no-loopback')
-        if hostname:
+        localhost = socket.gethostname()
+        if hostname and hostname != localhost:
             args = ['ssh', '-n', hostname]
             args.append(' '.join(cmd))
         else:
-            args = cmd
+            args = ['bash', '-c']
+            args.append(' '.join(cmd))
 
         result = subprocess.check_output(args).decode()
         return result.split('START_CMD_OUTPUT\n')[1].splitlines()

gpMgmt/bin/gppylib/operations/detect_unreachable_hosts.py

@@ -2,6 +2,7 @@
 from gppylib.commands.base import Command
 from gppylib.commands import base
 from gppylib.gparray import STATUS_DOWN
+import socket
 
 logger = gplog.get_default_logger()
 
@@ -12,8 +13,13 @@ def get_unreachable_segment_hosts(hosts, num_workers):
 
     pool = base.WorkerPool(numWorkers=num_workers)
     try:
+        localhost = socket.gethostname()
         for host in set(hosts):
-            cmd = Command(name='check %s is up' % host, cmdStr="ssh %s 'echo %s'" % (host, host))
+            cmd = None
+            if host != localhost:
+                cmd = Command(name='check %s is up' % host, cmdStr="ssh %s 'echo %s'" % (host, host))
+            else:
+                cmd = Command(name='check %s is up' % host, cmdStr="echo {}".format(host))
             pool.addCommand(cmd)
         pool.join()
     finally: