Raise an exception under Python < 3.4.

It also cleans up the README to remove references to Python 2
and removes Python 2-isms from the main config.

refs #5443

README

@@ -27,7 +27,7 @@ Building the Runtime
 To build the runtime, the following packages must be installed:
 
 - QT 4.6 or above (Use the VC++ build on Windows, not MinGW).
-- Python 2.7 or 3.4+
+- Python 3.4+
 
 Assuming both qmake and python-config are in the path:
 
@@ -36,7 +36,7 @@ Assuming both qmake and python-config are in the path:
     Project MESSAGE: Building for QT5+...
     Project MESSAGE: Building for Linux/Mac...
     Project MESSAGE: Using /usr/bin/python-config
-    Project MESSAGE: Python2 detected.
+    Project MESSAGE: Python3 detected.
     $ make
     ...
 
@@ -58,10 +58,10 @@ and minor number. Do not specify micro level version.
 For example, given a Python version of A.B.C; A - Major number, B - Minor
 number, C - Micro level (Bug fix releases).
 
-If Python version is 2.7.12 than specify PYTHON_VERSION=27
+If Python version is 3.8.2 than specify PYTHON_VERSION=38
 
- e.g. PYTHON_HOME=C:\Python27\
-      PYTHON_VERSION=27
+ e.g. PYTHON_HOME=C:\Python38\
+      PYTHON_VERSION=38
 
 You can also use Qt Creator to build, develop and debug the runtime. Simply
 open the $PGADMIN4_SRC/runtime/pgAdmin4.pro project file in Qt Creator and
@@ -88,10 +88,10 @@ Configuring the Python Environment
 ----------------------------------
 
 In order to run the Python code, a suitable runtime environment is required.
-Python versions - Python 2.7 or 3.4+ are currently supported. It is
-recommended that a Python Virtual Environment is setup for this purpose,
-rather than using the system Python environment. On Linux and Mac systems, the
-process is fairly simple - adapt as required for your distribution:
+Python version 3.4 and later are currently supported. It is recommended that a
+Python Virtual Environment is setup for this purpose, rather than using the
+system Python environment. On Linux and Mac systems, the process is fairly
+simple - adapt as required for your distribution:
 
 1) Install the virtualenv packages into the system Python environment
 
@@ -181,11 +181,10 @@ server or desktop mode, and access it from a web browser using the URL shown in
 the terminal once pgAdmin has started up.
 
 Setup of an environment on Windows is somewhat more complicated unfortunately,
-largely due to the lack of a native compiler toolset. Thankfully, Microsoft
-supply a free compiler specifically for Python 2.7 users. Download and install
-it from:
+largely due to the lack of a native compiler toolset. See the following wiki
+page for more information on the compiler you may need:
 
-https://www.microsoft.com/en-gb/download/details.aspx?id=44266
+https://wiki.python.org/moin/WindowsCompilers
 
 A blog detailing the setup of Virtual Environments on Windows can be found
 here:
@@ -324,10 +323,10 @@ Qt 5.5.1, Python 2.7 and Visual Studio 2013. The examples below are for a
 similar 32 bit system:
 
 INNOTOOL=C:\Program Files\Inno Setup 5
-PGDIR=C:\Program Files\PostgreSQL\10
-PYTHON_DLL=C:\Windows\System32\Python27.dll
-PYTHON_HOME=C:\Python27
-PYTHON_VERSION=27
+PGDIR=C:\Program Files\PostgreSQL\12
+PYTHON_DLL=C:\Python38\Python38.dll
+PYTHON_HOME=C:\Python38
+PYTHON_VERSION=38
 QTDIR=C:\Qt\5.9\msvc2013
 VCDIR=C:\Program Files\Microsoft Visual Studio 12.0\VC
 

web/config.py

@@ -11,15 +11,11 @@
 #
 ##########################################################################
 
+import builtins
 import logging
 import os
 import sys
-import json
 
-if sys.version_info[0] >= 3:
-    import builtins
-else:
-    import __builtin__ as builtins
 
 # We need to include the root directory in sys.path to ensure that we can
 # find everything we need when running in the standalone runtime.
@@ -27,7 +23,7 @@ root = os.path.dirname(os.path.realpath(__file__))
 if sys.path[0] != root:
     sys.path.insert(0, root)
 
-from pgadmin.utils import env, IS_PY2, IS_WIN, fs_short_path
+from pgadmin.utils import env, IS_WIN, fs_short_path
 
 ##########################################################################
 # Application settings
@@ -566,15 +562,6 @@ try:
 except ImportError:
     pass
 
-
-# SUPPORT_SSH_TUNNEL can be override in local config file and if that
-# setting is False in local config then we should not check the Python version.
-if (SUPPORT_SSH_TUNNEL is True and
-    ((sys.version_info[0] == 2 and sys.version_info[1] < 7) or
-     (sys.version_info[0] == 3 and sys.version_info[1] < 4))):
-    SUPPORT_SSH_TUNNEL = False
-    ALLOW_SAVE_TUNNEL_PASSWORD = False
-
 # Disable USER_INACTIVITY_TIMEOUT when SERVER_MODE=False
 if not SERVER_MODE:
     USER_INACTIVITY_TIMEOUT = 0

web/pgAdmin4.py

@@ -11,13 +11,14 @@
 a webserver, this will provide the WSGI interface, otherwise, we're going
 to start a web server."""
 
-import os
+
 import sys
 
-if sys.version_info[0] >= 3:
-    import builtins
-else:
-    import __builtin__ as builtins
+if sys.version_info < (3, 4):
+    raise Exception('This application must be run under Python 3.4 or later.')
+
+import builtins
+import os
 
 # We need to include the root directory in sys.path to ensure that we can
 # find everything we need when running in the standalone runtime.

web/regression/runtests.py

@@ -24,10 +24,10 @@ import coverage
 
 import unittest
 
-if sys.version_info[0] >= 3:
-    import builtins
-else:
-    import __builtin__ as builtins
+if sys.version_info < (3, 4):
+    raise Exception('The test suite must be run under Python 3.4 or later.')
+
+import builtins
 
 # Ensure the global server mode is set.
 builtins.SERVER_MODE = None