Merge pull request #3508 from alphagov/redis-ssl-181796569

Prepare to switch to Redis on PaaS

app/cloudfoundry_config.py

@@ -16,6 +16,9 @@ def set_config_env_vars(vcap_services):
     # Postgres config
     os.environ['SQLALCHEMY_DATABASE_URI'] = vcap_services['postgres'][0]['credentials']['uri'].replace('postgres',
                                                                                                        'postgresql')
+    # Redis config
+    if 'redis' in vcap_services:
+        os.environ['REDIS_URL'] = vcap_services['redis'][0]['credentials']['uri']
 
     vcap_application = json.loads(os.environ['VCAP_APPLICATION'])
     os.environ['NOTIFY_ENVIRONMENT'] = vcap_application['space_name']

gunicorn_config.py

@@ -2,6 +2,8 @@ import os
 import sys
 import traceback
 import gunicorn
+import eventlet
+import socket
 
 from gds_metrics.gunicorn import child_exit  # noqa
 
@@ -30,3 +32,22 @@ def on_exit(server):
 
 def worker_int(worker):
     worker.log.info("worker: received SIGINT {}".format(worker.pid))
+
+
+def fix_ssl_monkeypatching():
+    """
+    eventlet works by monkey-patching core IO libraries (such as ssl) to be non-blocking. However, there's currently
+    a bug: In the normal socket library it may throw a timeout error as a `socket.timeout` exception. However
+    eventlet.green.ssl's patch raises an ssl.SSLError('timed out',) instead. redispy handles socket.timeout but not
+    ssl.SSLError, so we solve this by monkey patching the monkey patching code to raise the correct exception type
+    :scream:
+
+    https://github.com/eventlet/eventlet/issues/692
+    """
+    # this has probably already been called somewhere in gunicorn internals, however, to be sure, we invoke it again.
+    # eventlet.monkey_patch can be called multiple times without issue
+    eventlet.monkey_patch()
+    eventlet.green.ssl.timeout_exc = socket.timeout
+
+
+fix_ssl_monkeypatching()

tests/app/test_cloudfoundry_config.py

@@ -10,39 +10,38 @@ from app.cloudfoundry_config import (
 
 
 @pytest.fixture
-def postgres_config():
-    return [
-        {
+def cloudfoundry_config():
+    return {
+        'postgres': [{
             'credentials': {
                 'uri': 'postgres uri'
             }
-        }
-    ]
-
-
-@pytest.fixture
-def cloudfoundry_config(postgres_config):
-    return {
-        'postgres': postgres_config,
+        }],
+        'redis': [{
+            'credentials': {
+                'uri': 'redis uri'
+            }
+        }],
         'user-provided': []
     }
 
 
 @pytest.fixture
-def cloudfoundry_environ(os_environ, cloudfoundry_config):
-    os.environ['VCAP_SERVICES'] = json.dumps(cloudfoundry_config)
+def vcap_application(os_environ):
     os.environ['VCAP_APPLICATION'] = '{"space_name": "🚀🌌"}'
 
 
-def test_extract_cloudfoundry_config_populates_other_vars(cloudfoundry_environ):
+def test_extract_cloudfoundry_config_populates_other_vars(cloudfoundry_config, vcap_application):
+    os.environ['VCAP_SERVICES'] = json.dumps(cloudfoundry_config)
     extract_cloudfoundry_config()
 
     assert os.environ['SQLALCHEMY_DATABASE_URI'] == 'postgresql uri'
+    assert os.environ['REDIS_URL'] == 'redis uri'
     assert os.environ['NOTIFY_ENVIRONMENT'] == '🚀🌌'
     assert os.environ['NOTIFY_LOG_PATH'] == '/home/vcap/logs/app.log'
 
 
-def test_set_config_env_vars_ignores_unknown_configs(cloudfoundry_config, cloudfoundry_environ):
+def test_set_config_env_vars_ignores_unknown_configs(cloudfoundry_config, vcap_application):
     cloudfoundry_config['foo'] = {'credentials': {'foo': 'foo'}}
     cloudfoundry_config['user-provided'].append({
         'name': 'bar', 'credentials': {'bar': 'bar'}
@@ -52,3 +51,9 @@ def test_set_config_env_vars_ignores_unknown_configs(cloudfoundry_config, cloudf
 
     assert 'foo' not in os.environ
     assert 'bar' not in os.environ
+
+
+def test_set_config_env_vars_copes_if_redis_not_set(cloudfoundry_config, vcap_application):
+    del cloudfoundry_config['redis']
+    set_config_env_vars(cloudfoundry_config)
+    assert 'REDIS_URL' not in os.environ