Use utf8mb4 for connections to MySQL in dev

settings.py

@@ -62,6 +62,10 @@ CORS_ENDPOINT_OVERRIDES = cors_endpoint_overrides(
     ['localhost:3000', 'olympia.test']
 )
 
+DATABASES = {
+    'default': get_db_config('DATABASES_DEFAULT_URL', charset='utf8mb4'),
+}
+
 # FxA config for local development only.
 FXA_CONFIG = {
     'default': {

src/olympia/conf/dev/settings.py

@@ -46,8 +46,8 @@ INBOUND_EMAIL_DOMAIN = env('INBOUND_EMAIL_DOMAIN',
                            default='addons-dev.allizom.org')
 
 DATABASES = {
-    'default': get_db_config('DATABASES_DEFAULT_URL'),
-    'slave': get_db_config('DATABASES_SLAVE_URL', atomic_requests=False),
+    'default': get_db_config('DATABASES_DEFAULT_URL', charset='utf8mb4'),
+    'slave': get_db_config('DATABASES_SLAVE_URL', atomic_requests=False, charset='utf8mb4'),
 }
 
 SERVICES_DATABASE = get_db_config('SERVICES_DATABASE_URL')

src/olympia/lib/settings_base.py

@@ -123,7 +123,9 @@ def cors_endpoint_overrides(whitelist_endpoints):
 CORS_ENDPOINT_OVERRIDES = []
 
 
-def get_db_config(environ_var, atomic_requests=True):
+def get_db_config(environ_var, atomic_requests=True, charset='utf8'):
+    assert charset in ('utf8', 'utf8mb4')
+    
     values = env.db(
         var=environ_var,
         default='mysql://root:@localhost/olympia')
@@ -137,12 +139,15 @@ def get_db_config(environ_var, atomic_requests=True):
         'CONN_MAX_AGE': 300,
         'ENGINE': 'olympia.core.db.mysql',
         'OPTIONS': {
+            'charset': charset,
             'sql_mode': 'STRICT_ALL_TABLES',
             'isolation_level': 'read committed'
         },
         'TEST': {
-            'CHARSET': 'utf8',
-            'COLLATION': 'utf8_general_ci'
+            'CHARSET': charset,
+            'COLLATION': (
+                'utf8_general_ci' if charset == 'utf8' else
+                'utf8mb4_general_ci')
         },
     })