Set environment variables indicating that mod_wsgi-express is being used and what debug modes.

Author: GrahamDumpleton

docs/release-notes/version-4.4.11.rst

@@ -33,3 +33,29 @@ specifying the name of a log file for a specific service script. The
 arguments are the name of the service and the file name for the log. The
 log file will be placed in the log directory, be it the default, or a
 specific log directory if specified.
+
+2. Set various environment variables from ``mod_wsgi-express`` to identify
+that it is being used, what hosts it is handling requests for, and whether
+debug mode and/or specific debug mode features are enabled. This is so that
+a web application can modify it's behaviour when ``mod_wsgi-express`` is
+being used, or being used in specific ways. The environment variables which
+are set are:
+
+* *MOD_WSGI_EXPRESS* - Indicates that ``mod_wsgi-express`` is being used.
+* *MOD_WSGI_SERVER_NAME* - The primary server host name for the site.
+* *MOD_WSGI_SERVER_ALIASES* - Secondary host names the site is known by.
+* *MOD_WSGI_RELOADER_ENABLED* - Indicates if source code reloading enabled.
+* *MOD_WSGI_DEBUG_MODE* - Indicates if debug mode has been enabled.
+* *MOD_WSGI_DEBUGGER_ENABLED* - Indicates pdb debugger has been enabled.
+* *MOD_WSGI_COVERAGE_ENABLED* - Indicates if coverage analysis has been
+  enabled.
+* *MOD_WSGI_PROFILER_ENABLED* - Indicates if code profiling has been enabled.
+* *MOD_WSGI_RECORDER_ENABLED* - Indicates if request/response recording
+  enabled.
+* *MOD_WSGI_GDB_ENABLED* - Indicates if gdb process crash debugging enabled.
+
+For any environment variable indicating a feature has been enabled, it
+will be set when enabled and have the value 'true'.
+
+For the list of server aliases, it will be a space separated list of host
+names.

src/server/__init__.py

@@ -1370,8 +1370,18 @@ def __call__(self, environ, start_response):
 profiler_directory = '%(profiler_directory)s'
 enable_recorder = %(enable_recorder)s
 recorder_directory = '%(recorder_directory)s'
+enable_gdb = %(enable_gdb)s
+
+os.environ['MOD_WSGI_EXPRESS'] = 'true'
+os.environ['MOD_WSGI_SERVER_NAME'] = '%(server_host)s'
+os.environ['MOD_WSGI_SERVER_ALIASES'] = %(server_aliases)r or ''
+
+if reload_on_changes:
+    os.environ['MOD_WSGI_RELOADER_ENABLED'] = 'true'
 
 if debug_mode:
+    os.environ['MOD_WSGI_DEBUG_MODE'] = 'true'
+
     # We need to fiddle sys.path as we are not using daemon mode and so
     # the working directory will not be added to sys.path by virtue of
     # 'home' option to WSGIDaemonProcess directive. We could use the
@@ -1380,11 +1390,16 @@ def __call__(self, environ, start_response):
 
     sys.path.insert(0, working_directory)
 
+if enable_debugger:
+    os.environ['MOD_WSGI_DEBUGGER_ENABLED'] = 'true'
+
 def output_coverage_report():
     coverage_info.stop()
     coverage_info.html_report(directory=coverage_directory)
 
 if enable_coverage:
+    os.environ['MOD_WSGI_COVERAGE_ENABLED'] = 'true'
+
     from coverage import coverage
     coverage_info = coverage()
     coverage_info.start()
@@ -1397,11 +1412,19 @@ def output_profiler_data():
     profiler_info.dump_stats(output_file)
 
 if enable_profiler:
+    os.environ['MOD_WSGI_PROFILER_ENABLED'] = 'true'
+
     from cProfile import Profile
     profiler_info = Profile()
     profiler_info.enable()
     atexit.register(output_profiler_data)
 
+if enable_recorder:
+    os.environ['MOD_WSGI_RECORDER_ENABLED'] = 'true'
+
+if enable_gdb:
+    os.environ['MOD_WSGI_GDB_ENABLED'] = 'true'
+
 if with_newrelic_agent:
     if newrelic_config_file:
         os.environ['NEW_RELIC_CONFIG_FILE'] = newrelic_config_file
@@ -2714,6 +2737,8 @@ def _cmd_setup_server(command, args, options):
     else:
         host = options['host']
 
+    options['server_host'] = host
+
     if options['port'] == 80:
         options['url'] = 'http://%s/' % host
     else: