Stub SES email client to avoid hitting SES during load testing

If we set an environment variable, we can stub out calls to SES and send
them to our own stub app. If the environment variable is not set, things
work as normal.

To be used alongside
https://github.com/alphagov/notifications-email-provider-stub

app/__init__.py

@@ -21,6 +21,7 @@ from app.celery.celery import NotifyCelery
 from app.clients import Clients
 from app.clients.document_download import DocumentDownloadClient
 from app.clients.email.aws_ses import AwsSesClient
+from app.clients.email.aws_ses_stub import AwsSesStubClient
 from app.clients.sms.firetext import FiretextClient
 from app.clients.sms.mmg import MMGClient
 from app.clients.performance_platform.performance_platform_client import PerformancePlatformClient
@@ -49,6 +50,7 @@ notify_celery = NotifyCelery()
 firetext_client = FiretextClient()
 mmg_client = MMGClient()
 aws_ses_client = AwsSesClient()
+aws_ses_stub_client = AwsSesStubClient()
 encryption = Encryption()
 zendesk_client = ZendeskClient()
 statsd_client = StatsdClient()
@@ -81,13 +83,22 @@ def create_app(application):
     logging.init_app(application, statsd_client)
     firetext_client.init_app(application, statsd_client=statsd_client)
     mmg_client.init_app(application, statsd_client=statsd_client)
+
     aws_ses_client.init_app(application.config['AWS_REGION'], statsd_client=statsd_client)
+    aws_ses_stub_client.init_app(
+        application.config['AWS_REGION'],
+        statsd_client=statsd_client,
+        stub_url=os.environ.get('SES_STUB_URL')
+    )
+    # If a stub url is provided for SES, then use the stub client rather than the real SES boto client
+    email_clients = [aws_ses_client] if not os.environ.get('SES_STUB_URL') else [aws_ses_stub_client]
+    clients.init_app(sms_clients=[firetext_client, mmg_client], email_clients=email_clients)
+
     notify_celery.init_app(application)
     encryption.init_app(application)
     redis_store.init_app(application)
     performance_platform_client.init_app(application)
     document_download_client.init_app(application)
-    clients.init_app(sms_clients=[firetext_client, mmg_client], email_clients=[aws_ses_client])
     metrics.init_app(application)
 
     register_blueprint(application)

app/clients/email/aws_ses_stub.py

@@ -0,0 +1,49 @@
+import json
+
+from flask import current_app
+from requests import request
+from time import monotonic
+
+from app.clients.email import (EmailClientException, EmailClient)
+
+
+class AwsSesStubClientException(EmailClientException):
+    pass
+
+
+class AwsSesStubClient(EmailClient):
+    def init_app(self, region, statsd_client, stub_url):
+        self.name = 'ses'
+        self.statsd_client = statsd_client
+        self.url = stub_url
+
+    def get_name(self):
+        return self.name
+
+    def send_email(self,
+                   source,
+                   to_addresses,
+                   subject,
+                   body,
+                   html_body='',
+                   reply_to_address=None):
+        try:
+            start_time = monotonic()
+            response = request(
+                "POST",
+                self.url,
+                data={"id": "dummy-data"},
+                timeout=60
+            )
+            response.raise_for_status()
+            response_json = json.loads(response.text)
+
+        except Exception as e:
+            self.statsd_client.incr("clients.ses_stub.error")
+            raise AwsSesStubClientException(str(e))
+        else:
+            elapsed_time = monotonic() - start_time
+            current_app.logger.info("AWS SES stub request finished in {}".format(elapsed_time))
+            self.statsd_client.timing("clients.ses_stub.request-time", elapsed_time)
+            self.statsd_client.incr("clients.ses_stub.success")
+            return response_json['MessageId']

app/config.py

@@ -345,6 +345,7 @@ class Config(object):
     # these environment vars aren't defined in the manifest so to set them on paas use `cf set-env`
     MMG_URL = os.environ.get("MMG_URL", "https://api.mmg.co.uk/jsonv2a/api.php")
     FIRETEXT_URL = os.environ.get("FIRETEXT_URL", "https://www.firetext.co.uk/api/sendsms/json")
+    SES_STUB_URL = os.environ.get("SES_STUB_URL")
 
     AWS_REGION = 'eu-west-1'