Get SECRET_KEY from environment

.circleci/config.yml

@@ -4,6 +4,9 @@ jobs:
     docker:
       - image: python:3
 
+    environment:
+      SECRET_KEY: DEV
+
     steps:
       - checkout
       - run: pip install pytest coverage

flaskr/__init__.py

@@ -7,8 +7,8 @@ def create_app(test_config=None):
     # create and configure the app
     app = Flask(__name__, instance_relative_config=True)
     app.config.from_mapping(
-        SECRET_KEY='dev',
         DATABASE=os.path.join(app.instance_path, 'flaskr.sqlite'),
+        SECRET_KEY = os.environ.get("SECRET_KEY", default=None)
     )
 
     if test_config is None: