Ambari-7767. Add an agent config to discover server hostname via a script (Chuan Liu via smohanty)

ambari-agent/src/main/python/ambari_agent/AmbariConfig.py

@@ -20,6 +20,7 @@ limitations under the License.
 
 import ConfigParser
 import StringIO
+import hostname
 import json
 from NetUtil import NetUtil
 import os
@@ -231,7 +232,7 @@ class AmbariConfig:
 
   def get_api_url(self):
     return "%s://%s:%s" % (self.CONNECTION_PROTOCOL,
-                           self.get('server', 'hostname'),
+                           hostname.server_hostname(self),
                            self.get('server', 'url_port'))
 
   def isTwoWaySSLConnection(self):

ambari-agent/src/main/python/ambari_agent/Controller.py

@@ -63,7 +63,7 @@ class Controller(threading.Thread):
     self.credential = None
     self.config = config
     self.hostname = hostname.hostname(config)
-    self.serverHostname = config.get('server', 'hostname')
+    self.serverHostname = hostname.server_hostname(config)
     server_secured_url = 'https://' + self.serverHostname + \
                          ':' + config.get('server', 'secured_url_port')
     self.registerUrl = server_secured_url + '/agent/v1/register/' + self.hostname

ambari-agent/src/main/python/ambari_agent/hostname.py

@@ -29,6 +29,7 @@ logger = logging.getLogger()
 
 cached_hostname = None
 cached_public_hostname = None
+cached_server_hostname = None
 
 
 def hostname(config):
@@ -66,6 +67,7 @@ def public_hostname(config):
       out, err = output.communicate()
       if (0 == output.returncode and 0 != len(out.strip())):
         cached_public_hostname = out.strip()
+        logger.info("Read public hostname " + cached_public_hostname + "using agent:public_hostname_script")
         return cached_public_hostname
   except:
     #ignore for now.
@@ -84,9 +86,31 @@ def public_hostname(config):
     cached_public_hostname = socket.getfqdn().lower()
   return cached_public_hostname
 
+def server_hostname(config):
+  global cached_server_hostname
+  if cached_server_hostname is not None:
+    return cached_server_hostname
+
+  if config.has_option('server', 'hostname_script'):
+    scriptname = config.get('server', 'hostname_script')
+    try:
+      osStat = subprocess.Popen([scriptname], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+      out, err = osStat.communicate()
+      if (0 == osStat.returncode and 0 != len(out.strip())):
+        cached_server_hostname = out.strip()
+        logger.info("Read server hostname " + cached_server_hostname + "using server:hostname_script")
+    except Exception, err:
+      logger.info("Unable to execute hostname_script for server hostname. " + str(err))
+
+  if cached_server_hostname is None:
+    cached_server_hostname  = config.get('server', 'hostname')
+  return cached_server_hostname
+
+
 def main(argv=None):
   print hostname()
   print public_hostname()
+  print server_hostname()
 
 if __name__ == '__main__':
   main()

ambari-agent/src/main/python/ambari_agent/main.py

@@ -247,7 +247,7 @@ def main(heartbeat_stop_callback=None):
 
   update_log_level(config)
 
-  server_hostname = config.get('server', 'hostname')
+  server_hostname = hostname.server_hostname(config)
   server_url = config.get_api_url()
 
   if not OSCheck.get_os_family() == OSConst.WINSRV_FAMILY:

ambari-agent/src/main/python/ambari_agent/security.py

@@ -106,7 +106,7 @@ class CachedHTTPSConnection:
   def __init__(self, config):
     self.connected = False
     self.config = config
-    self.server = config.get('server', 'hostname')
+    self.server = hostname.server_hostname(config)
     self.port = config.get('server', 'secured_url_port')
     self.connect()
 
@@ -143,7 +143,7 @@ class CertificateManager():
     self.config = config
     self.keysdir = os.path.abspath(self.config.get('security', 'keysdir'))
     self.server_crt = self.config.get('security', 'server_crt')
-    self.server_url = 'https://' + self.config.get('server', 'hostname') + ':' \
+    self.server_url = 'https://' + hostname.server_hostname(config) + ':' \
        + self.config.get('server', 'url_port')
 
   def getAgentKeyName(self):

ambari-agent/src/test/python/ambari_agent/TestHostname.py

@@ -28,7 +28,7 @@ import shutil
 import os, pprint, json,stat
 from mock.mock import patch, MagicMock
 from ambari_commons import OSCheck
-from only_for_platform import only_for_platform, get_platform, PLATFORM_LINUX, PLATFORM_WINDOWS
+from only_for_platform import only_for_platform, get_platform, not_for_platform, PLATFORM_LINUX, PLATFORM_WINDOWS
 
 if get_platform() != PLATFORM_WINDOWS:
   os_distro_value = ('Suse','11','Final')
@@ -46,6 +46,38 @@ class TestHostname(TestCase):
                       "hostname should equal the socket-based hostname")
     pass
 
+  def test_server_hostname(self):
+    hostname.cached_server_hostname = None
+    config = AmbariConfig()
+    default_server_hostname = config.get('server', 'hostname')
+    config.set('server', 'hostname', 'ambari-host')
+    self.assertEquals('ambari-host', hostname.server_hostname(config),
+                      "hostname should equal the socket-based hostname")
+    config.set('server', 'hostname', default_server_hostname)
+    pass
+
+  @not_for_platform(PLATFORM_WINDOWS)
+  def test_server_hostname_override(self):
+    hostname.cached_server_hostname = None
+    fd = tempfile.mkstemp(text=True)
+    tmpname = fd[1]
+    os.close(fd[0])
+    os.chmod(tmpname, os.stat(tmpname).st_mode | stat.S_IXUSR)
+
+    tmpfile = file(tmpname, "w+")
+    config = AmbariConfig()
+    try:
+      tmpfile.write("#!/bin/sh\n\necho 'test.example.com'")
+      tmpfile.close()
+
+      config.set('server', 'hostname_script', tmpname)
+
+      self.assertEquals(hostname.server_hostname(config), 'test.example.com', "expected hostname 'test.example.com'")
+    finally:
+      os.remove(tmpname)
+      config.remove_option('server', 'hostname_script')
+    pass
+
   @only_for_platform(PLATFORM_LINUX)
   def test_hostname_override(self):
     hostname.cached_hostname = None