Added amqp

storage_service/utils/__init__.py

@@ -3,3 +3,4 @@ from .require_decorators import json_required
 from .error_handlers import register_all_error_handlers
 from .storage import storage
 from .healthchecks import register_health_checks
+from .magic_amqp import magic_amqp

storage_service/utils/healthchecks.py

@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-from utils import storage
+from utils import storage, magic_amqp
 from healthcheck import HealthCheck
 from flask import Flask
 
@@ -15,7 +15,19 @@ def health_database_status():
     return is_database_working, output
 
 
+def amqp_connection_status():
+    if magic_amqp.is_healthy():
+        result = True
+        text = "amqp connection is ok"
+    else:
+        result = False
+        text = "amqp connection is unhealthy"
+
+    return result, text
+
+
 def register_health_checks(app: Flask):
     health = HealthCheck()
     health.add_check(health_database_status)
+    health.add_check(amqp_connection_status)
     app.add_url_rule("/healthz", "healthcheck", view_func=lambda: health.run())

storage_service/utils/magic_amqp.py

@@ -0,0 +1,120 @@
+from flask import Flask
+from threading import Lock
+import pika
+import pika.exceptions
+import json
+import time
+
+import opentracing
+from opentracing.ext import tags
+from opentracing.propagation import Format
+
+
+class MagicAMQP:
+    """
+    This is my pathetic attempt to make RabbitMQ connection in a Flask app reliable and performant.
+    """
+
+    def __init__(self, app: Flask = None):
+        self.app = app
+        if app:
+            self.init_app(app)
+
+        self._lock = Lock()
+        self._credentials = None
+
+    def init_app(self, app: Flask):
+        self.app = app
+        self.app.config.setdefault('PIKA_URL', None)
+        self.app.config.setdefault('EXCHANGE_NAME', None)
+
+        self._reconnect_ampq()
+
+    def _reconnect_ampq(self):
+        self._pika_connection = pika.BlockingConnection(pika.connection.URLParameters(self.app.config['PIKA_URL']))
+        self._pika_channel = self._pika_connection.channel()
+        self._pika_channel.exchange_declare(
+            exchange=self.app.config['EXCHANGE_NAME'],
+            exchange_type='direct'
+        )
+
+    def loop(self):
+        """
+        This method should be called periodically to keep up the connection
+        """
+        lock_start = time.time()
+        with self._lock:
+            lock_acquire_time = time.time() - lock_start
+            if lock_acquire_time >= 0.5:
+                self.app.logger.warning(f"Loop: Lock acquire took {lock_acquire_time:5f} sec")
+
+            try:
+                self._pika_connection.process_data_events(0)
+                # We won't attempt retry if this fail
+            except pika.exceptions.AMQPConnectionError as e:
+                self.app.logger.warning(f"Connection error during process loop: {e} (attempting reconnect)")
+                self._reconnect_ampq()
+
+            total_time = time.time() - lock_start
+            if total_time > 1:
+                self.app.logger.warning(f"Loop: Total loop took {total_time:5f} sec")
+
+    def publish(self, payload=None):
+        """
+        Publish a simple json serialized message to the configured queue.
+        If the connection is broken, then this call will block until the connection is restored
+        """
+        span_tags = {tags.SPAN_KIND: tags.SPAN_KIND_PRODUCER}
+        with opentracing.tracer.start_active_span('magic_amqp.publish', tags=span_tags) as scope:
+            opentracing.tracer.inject(scope.span.context, Format.TEXT_MAP, payload)
+            lock_start = time.time()
+            with self._lock:
+                scope.span.log_kv({'event': 'lockAcquired'})
+                lock_acquire_time = time.time() - lock_start
+                if lock_acquire_time >= 0.2:
+                    self.app.logger.warning(f"Publish: Lock acquire took {lock_acquire_time:5f} sec")
+                tries = 0
+                while True:
+                    try:
+                        self._pika_channel.basic_publish(
+                            exchange=self.app.config['EXCHANGE_NAME'],
+                            routing_key="sample",
+                            body=json.dumps(payload).encode('UTF-8')
+                        )
+                        self.app.logger.debug(f"Published: {payload}")
+                        break  # message sent successfully
+                    except pika.exceptions.AMQPConnectionError as e:
+                        scope.span.log_kv({'event': 'connectionError', 'error': str(e)})
+                        self.app.logger.warning(f"Connection error during publish: {e} (attempting reconnect)")
+
+                        if tries > 30:
+                            raise  # just give up
+
+                        while True:
+                            try:
+                                self._reconnect_ampq()
+                                break
+                            except pika.exceptions.AMQPConnectionError as e:
+                                self.app.logger.warning(
+                                    f"Connection error during reconnection: {e} (attempting reconnect)")
+                                tries += 1
+
+                                if tries > 30:
+                                    raise  # just give up
+
+                            if tries > 10:
+                                time.sleep(2)
+                total_time = time.time() - lock_start
+                if total_time > 0.4:
+                    self.app.logger.warning(f"Publish: Total publish took {total_time:5f} sec")
+
+    def is_healthy(self) -> bool:
+        with self._lock:
+            if not self._pika_channel:
+                return False
+
+            return self._pika_channel.is_open and self._pika_connection.is_open
+
+
+# instance to be used in the flask app
+magic_amqp = MagicAMQP()