Get an actual free random port instead of a random port number

beat/core/execution/docker.py

@@ -32,7 +32,6 @@ import os
 import requests
 import simplejson
 import zmq
-import random
 
 import logging
 logger = logging.getLogger(__name__)
@@ -254,7 +253,7 @@ class DockerExecutor(RemoteExecutor):
 
             # Creation of the container
             # Note: we only support one databases image loaded at the same time
-            database_port = random.randint(51000, 60000)
+            database_port = utils.find_free_port()
 
             cmd = [
                 'databases_provider',
@@ -293,7 +292,7 @@ class DockerExecutor(RemoteExecutor):
                         break
 
                     databases_container.reset_ports()
-                    database_port = random.randint(51000, 60000)
+                    database_port = utils.find_free_port()
 
                     cmd = [x if not x.startswith('0.0.0.0:') else '0.0.0.0:%d' % database_port for x in cmd]
                     databases_container.command = cmd

beat/core/execution/subprocess.py

@@ -33,7 +33,6 @@ from __future__ import absolute_import
 import os
 import requests
 import zmq
-import random
 import sys
 import subprocess as sp
 import tempfile
@@ -240,7 +239,7 @@ class SubprocessExecutor(RemoteExecutor):
         #----- (If necessary) Instantiate the subprocess that provide the databases
 
         databases_process = None
-        database_port = random.randint(51000, 60000)
+        database_port = utils.find_free_port()
 
         if len(self.databases) > 0:
 

beat/core/utils.py

@@ -29,6 +29,8 @@
 import os
 import sys
 import tempfile
+import socket
+import contextlib
 
 import numpy
 import simplejson
@@ -66,6 +68,9 @@ def uniq(seq):
     return result
 
 
+#----------------------------------------------------------
+
+
 def send_multipart(socket, parts):
     """
     Send the parts through the socket after having encoded them if
@@ -77,3 +82,15 @@ def send_multipart(socket, parts):
             parts[index] = item.encode('utf-8')
 
     socket.send_multipart(parts)
+
+
+#----------------------------------------------------------
+
+
+def find_free_port():
+    '''Returns the value of a free random port'''
+
+    with contextlib.closing(socket.socket(socket.AF_INET,
+      socket.SOCK_STREAM)) as s:
+        s.bind(('', 0))
+        return s.getsockname()[1]