Return 404 response for missing log file. Closes Supervisor#1406

CHANGES.rst

@@ -1,6 +1,12 @@
 4.3.0.dev0 (Next Release)
 -------------------------
 
+- The web interface will now return a 404 Not Found response if a log file
+  is missing.  Previously, it would return 410 Gone.  It was changed because
+  410 is intended to mean that the condition is likely to be permanent.  A
+  log file missing is usually temporary, e.g. a process that was never started
+  will not have a log file but will have one as soon as it is started.
+
 4.2.2 (2021-02-26)
 ------------------
 

supervisor/http.py

@@ -737,10 +737,11 @@ def handle_request(self, request):
         logfile = getattr(process.config, '%s_logfile' % channel, None)
 
         if logfile is None or not os.path.exists(logfile):
-            # XXX problematic: processes that don't start won't have a log
-            # file and we probably don't want to go into fatal state if we try
-            # to read the log of a process that did not start.
-            request.error(410) # gone
+            # we return 404 because no logfile is a temporary condition.
+            # if the process has never been started, no logfile will exist
+            # on disk.  a logfile of None is also a temporay condition,
+            # since the config file can be reloaded.
+            request.error(404) # not found
             return
 
         mtime = os.stat(logfile)[stat.ST_MTIME]
@@ -774,7 +775,10 @@ def handle_request(self, request):
         logfile = self.supervisord.options.logfile
 
         if logfile is None or not os.path.exists(logfile):
-            request.error(410) # gone
+            # we return 404 because no logfile is a temporary condition.
+            # even if a log file of None is configured, the config file
+            # may be reloaded, and the new config may have a logfile.
+            request.error(404) # not found
             return
 
         mtime = os.stat(logfile)[stat.ST_MTIME]

supervisor/tests/test_http.py

@@ -45,7 +45,7 @@ def test_handle_request_stdout_logfile_none(self):
         handler = self._makeOne(supervisord)
         request = DummyRequest('/logtail/process1', None, None, None)
         handler.handle_request(request)
-        self.assertEqual(request._error, 410)
+        self.assertEqual(request._error, 404)
 
     def test_handle_request_stdout_logfile_missing(self):
         options = DummyOptions()
@@ -54,7 +54,7 @@ def test_handle_request_stdout_logfile_missing(self):
         handler = self._makeOne(supervisord)
         request = DummyRequest('/logtail/foo', None, None, None)
         handler.handle_request(request)
-        self.assertEqual(request._error, 410)
+        self.assertEqual(request._error, 404)
 
     def test_handle_request(self):
         with tempfile.NamedTemporaryFile() as f:
@@ -84,15 +84,15 @@ def test_handle_request_stdout_logfile_none(self):
         handler = self._makeOne(supervisor)
         request = DummyRequest('/mainlogtail', None, None, None)
         handler.handle_request(request)
-        self.assertEqual(request._error, 410)
+        self.assertEqual(request._error, 404)
 
     def test_handle_request_stdout_logfile_missing(self):
         supervisor = DummySupervisor()
         supervisor.options.logfile = '/not/there'
         request = DummyRequest('/mainlogtail', None, None, None)
         handler = self._makeOne(supervisor)
         handler.handle_request(request)
-        self.assertEqual(request._error, 410)
+        self.assertEqual(request._error, 404)
 
     def test_handle_request(self):
         supervisor = DummySupervisor()