implement plugin framework for tracer

shards/mishards/__init__.py

@@ -19,17 +19,22 @@ def create_app(testing_config=None):
     from sd import ProviderManager
 
     sd_proiver_class = ProviderManager.get_provider(settings.SD_PROVIDER)
-    discover = sd_proiver_class(settings=settings.SD_PROVIDER_SETTINGS, conn_mgr=connect_mgr)
+    discover = sd_proiver_class(settings=settings.SD_PROVIDER_SETTINGS,
+                                conn_mgr=connect_mgr)
 
-    from tracing.factory import TracerFactory
     from mishards.grpc_utils import GrpcSpanDecorator
-    tracer = TracerFactory.new_tracer(config.TRACING_TYPE, settings.TracingConfig,
-                                      span_decorator=GrpcSpanDecorator())
+    from tracer.factory import TracerFactory
+    tracer = TracerFactory(config.TRACING_PLUGIN_PATH).create(config.TRACING_TYPE,
+                                    settings.TracingConfig,
+                                    span_decorator=GrpcSpanDecorator())
 
     from mishards.routings import RouterFactory
     router = RouterFactory.new_router(config.ROUTER_CLASS_NAME, connect_mgr)
 
-    grpc_server.init_app(conn_mgr=connect_mgr, tracer=tracer, router=router, discover=discover)
+    grpc_server.init_app(conn_mgr=connect_mgr,
+                         tracer=tracer,
+                         router=router,
+                         discover=discover)
 
     from mishards import exception_handlers
 

shards/mishards/settings.py

@@ -74,6 +74,7 @@ class TracingConfig:
 class DefaultConfig:
     SQLALCHEMY_DATABASE_URI = env.str('SQLALCHEMY_DATABASE_URI')
     SQL_ECHO = env.bool('SQL_ECHO', False)
+    TRACING_PLUGIN_PATH = env.str('TRACING_PLUGIN_PATH', '')
     TRACING_TYPE = env.str('TRACING_TYPE', '')
     ROUTER_CLASS_NAME = env.str('ROUTER_CLASS_NAME', 'FileBasedHashRingRouter')
 

shards/requirements.txt

@@ -34,3 +34,4 @@ urllib3==1.25.3
 jaeger-client>=3.4.0
 grpcio-opentracing>=1.0
 mock==2.0.0
+pluginbase==1.0.0

shards/tracer/factory.py

@@ -0,0 +1,48 @@
+import os
+import logging
+from functools import partial
+from pluginbase import PluginBase
+
+
+logger = logging.getLogger(__name__)
+
+here = os.path.abspath(os.path.dirname(__file__))
+get_path = partial(os.path.join, here)
+
+PLUGIN_PACKAGE_NAME = 'tracer.plugins'
+plugin_base = PluginBase(package=PLUGIN_PACKAGE_NAME,
+        searchpath=[get_path('./plugins')])
+
+class TracerFactory(object):
+    def __init__(self, searchpath=None):
+        self.plugin_package_name = PLUGIN_PACKAGE_NAME
+        self.tracer_map = {}
+        searchpath = searchpath if searchpath else []
+        searchpath = [searchpath] if isinstance(searchpath, str) else searchpath
+        self.source = plugin_base.make_plugin_source(
+                searchpath=searchpath, identifier=self.__class__.__name__)
+
+        for plugin_name in self.source.list_plugins():
+            plugin = self.source.load_plugin(plugin_name)
+            plugin.setup(self)
+
+    def on_plugin_setup(self, plugin_class):
+        name = getattr(plugin_class, 'name', plugin_class.__name__)
+        self.tracer_map[name.lower()] = plugin_class
+
+    def plugin(self, name):
+        return self.tracer_map.get(name, None)
+
+    def create(self,
+            tracer_type,
+            tracer_config,
+            span_decorator=None,
+            **kwargs):
+        if not tracer_type:
+            return Tracer()
+        plugin_class = self.plugin(tracer_type.lower())
+        if not plugin_class:
+            raise RuntimeError('Tracer Plugin \'{}\' not installed!'.format(tracer_type))
+
+        tracer = plugin_class.create(tracer_config, span_decorator=span_decorator, **kwargs)
+        return tracer

shards/tracer/plugins/jaeger_factory.py

@@ -0,0 +1,33 @@
+import logging
+from jaeger_client import Config
+from grpc_opentracing.grpcext import intercept_server
+from grpc_opentracing import open_tracing_server_interceptor
+from tracer import Tracer
+
+logger = logging.getLogger(__name__)
+
+PLUGIN_NAME = __name__
+
+class JaegerFactory:
+    name = 'jaeger'
+    @classmethod
+    def create(cls, tracer_config, span_decorator=None, **kwargs):
+        tracing_config = tracer_config.TRACING_CONFIG
+        service_name = tracer_config.TRACING_SERVICE_NAME
+        validate = tracer_config.TRACING_VALIDATE
+        config = Config(config=tracing_config,
+                        service_name=service_name,
+                        validate=validate)
+
+        tracer = config.initialize_tracer()
+        tracer_interceptor = open_tracing_server_interceptor(
+            tracer,
+            log_payloads=tracer_config.TRACING_LOG_PAYLOAD,
+            span_decorator=span_decorator)
+
+        return Tracer(tracer, tracer_interceptor, intercept_server)
+
+
+def setup(app):
+    logger.debug('Plugin \'{}\' Installed In Package: {}'.format(PLUGIN_NAME, app.plugin_package_name))
+    app.on_plugin_setup(JaegerFactory)

shards/tracing/factory.py

@@ -1,40 +0,0 @@
-import logging
-from jaeger_client import Config
-from grpc_opentracing.grpcext import intercept_server
-from grpc_opentracing import open_tracing_server_interceptor
-
-from tracing import (Tracer, empty_server_interceptor_decorator)
-
-logger = logging.getLogger(__name__)
-
-
-class TracerFactory:
-    @classmethod
-    def new_tracer(cls,
-                   tracer_type,
-                   tracer_config,
-                   span_decorator=None,
-                   **kwargs):
-        if not tracer_type:
-            return Tracer()
-        config = tracer_config.TRACING_CONFIG
-        service_name = tracer_config.TRACING_SERVICE_NAME
-        validate = tracer_config.TRACING_VALIDATE
-        # if not tracer_type:
-        #     tracer_type = 'jaeger'
-        #     config = tracer_config.DEFAULT_TRACING_CONFIG
-
-        if tracer_type.lower() == 'jaeger':
-            config = Config(config=config,
-                            service_name=service_name,
-                            validate=validate)
-
-            tracer = config.initialize_tracer()
-            tracer_interceptor = open_tracing_server_interceptor(
-                tracer,
-                log_payloads=tracer_config.TRACING_LOG_PAYLOAD,
-                span_decorator=span_decorator)
-
-            return Tracer(tracer, tracer_interceptor, intercept_server)
-
-        assert False, 'Unsupported tracer type: {}'.format(tracer_type)