Merge pull request #158 from skoranda/ping_frontend

First commit of the ping frontend

Author: johanlundberg

doc/README.md

@@ -407,6 +407,13 @@ for information on how to obtain them.
 A list of all user attributes released by Facebook can be found [here](https://developers.facebook.com/docs/graph-api/reference/v2.5/user),
 which should be used when configuring the attribute mapping (see above).
 
+### Ping frontend for simple heartbeat monitoring
+
+The ping frontend responds to a query with a simple
+200 OK and is intended to be used as a simple heartbeat monitor, 
+for example by a load balancer. The default configuration file can
+be found [here](../example/plugins/frontends/ping_frontend.yaml.example).
+
 ### Micro services
 
 Additional behaviour can be configured in the proxy through so called *micro services*. There are two different types

example/plugins/frontends/ping_frontend.yaml.example

@@ -0,0 +1,5 @@
+module:
+  ping.PingFrontend
+name:
+  ping
+config:

src/satosa/frontends/ping.py

@@ -0,0 +1,58 @@
+import satosa.micro_services.base
+from satosa.logging_util import satosa_logging
+
+from satosa.response import Response
+
+import logging
+
+logger = logging.getLogger(__name__)
+
+class PingFrontend(satosa.frontends.base.FrontendModule):
+    """
+    SATOSA frontend that responds to a query with a simple
+    200 OK, intended to be used as a simple heartbeat monitor.
+    """
+    logprefix = "PING:"
+
+    def __init__(self, auth_req_callback_func, internal_attributes, config, base_url, name):
+        super().__init__(auth_req_callback_func, internal_attributes, base_url, name)
+
+        self.config = config
+
+    def handle_authn_response(self, context, internal_resp, extra_id_token_claims=None):
+        """
+        See super class method satosa.frontends.base.FrontendModule#handle_authn_response
+        :type context: satosa.context.Context
+        :type internal_response: satosa.internal_data.InternalResponse
+        :rtype oic.utils.http_util.Response
+        """
+        raise NotImplementedError()
+
+    def handle_backend_error(self, exception):
+        """
+        See super class satosa.frontends.base.FrontendModule
+        :type exception: satosa.exception.SATOSAError
+        :rtype: oic.utils.http_util.Response
+        """
+        raise NotImplementedError()
+
+    def register_endpoints(self, backend_names):
+        """
+        See super class satosa.frontends.base.FrontendModule
+        :type backend_names: list[str]
+        :rtype: list[(str, ((satosa.context.Context, Any) -> satosa.response.Response, Any))]
+        :raise ValueError: if more than one backend is configured
+        """
+        url_map = [("^{}".format(self.name), self.ping_endpoint)]
+
+        return url_map
+
+    def ping_endpoint(self, context):
+        """
+        """
+        logprefix = PingFrontend.logprefix
+        satosa_logging(logger, logging.DEBUG, "{} ping returning 200 OK".format(logprefix), context.state)
+
+        msg = " "
+
+        return Response(msg)