first commit

docs/ENVIRONMENT.rst

@@ -19,6 +19,8 @@ Global/Universal
 -  **PATRONI\_LOG\_FILE\_NUM**: The number of application logs to retain.
 -  **PATRONI\_LOG\_FILE\_SIZE**: Size of patroni.log file (in bytes) that triggers a log rolling.
 -  **PATRONI\_LOG\_LOGGERS**: Redefine logging level per python module. Example ``PATRONI_LOG_LOGGERS="{patroni.postmaster: WARNING, urllib3: DEBUG}"``
+-  **PATRONI\_DEBUG\_MODE**: When set to a non-empty value, makes Patroni run in the special debug mode that enables stepping with a debugger through some execution paths within Patroni `
+Example ``PATRONI_DEBUG_MODE="on"``
 
 Bootstrap configuration
 -----------------------

patroni.py

@@ -1,6 +1,14 @@
 #!/usr/bin/env python
 from patroni import main
 
+import os
 
 if __name__ == '__main__':
+
+    if os.getenv("PATRONI_DEBUG_MODE"):
+        # XXX Visual Code specific https://github.com/microsoft/ptvsd/issues/1443
+        # create processes by spawning new Python interpreters instead of forking the current one 
+        import multiprocessing
+        multiprocessing.set_start_method('spawn', True)
+
     main()

patroni/__init__.py

@@ -32,6 +32,7 @@ class Patroni(object):
         self.postgresql = Postgresql(self.config['postgresql'])
         self.api = RestApiServer(self, self.config['restapi'])
         self.ha = Ha(self)
+        self.is_in_debug_mode = bool(os.getenv("PATRONI_DEBUG_MODE"))
 
         self.tags = self.get_tags()
         self.next_run = time.time()
@@ -102,8 +103,9 @@ class Patroni(object):
             self.next_run = current_time
             # Release the GIL so we don't starve anyone waiting on async_executor lock
             time.sleep(0.001)
-            # Warn user that Patroni is not keeping up
-            logger.warning("Loop time exceeded, rescheduling immediately.")
+            # Warn user that Patroni is not keeping up or runs in debug
+            msg = "Patroni runs in the debug mode: keys' TTL is infinite, loop wait disabled" if self.is_in_debug_mode else "Loop time exceeded, rescheduling immediately."
+            logger.warning(msg)
         elif self.ha.watch(nap_time):
             self.next_run = time.time()
 

patroni/config.py

@@ -333,6 +333,11 @@ class Config(object):
             elif name not in config or name in ['watchdog']:
                 config[name] = deepcopy(value) if value else {}
         
+        if os.getenv("PATRONI_DEBUG_MODE"):
+            config['ttl'] = 24 * 60 * 60 # practical infinity for a debugging session
+            config['loop_wait'] = -1
+
+
         # restapi server expects to get restapi.auth = 'username:password'
         if 'authentication' in config['restapi']:
             config['restapi']['auth'] = '{username}:{password}'.format(**config['restapi']['authentication'])