fix(config): read secret key from env (#475)

Make sure the secret key is propagated to the Flask app, instead of
incorrectly using the default one.

reana_job_controller/config.py

@@ -9,11 +9,20 @@
 """Flask application configuration."""
 
 import os
+import secrets
 
 from reana_commons.config import REANA_COMPONENT_PREFIX
 
 from werkzeug.utils import import_string
 
+
+SECRET_KEY = os.getenv("REANA_SECRET_KEY", secrets.token_hex())
+"""Secret key used for the application user sessions.
+
+A new random key is generated on every start of job-controller, but this is not an
+issues as job-controller is never restarted (and thus the secret never changes)
+during the execution of a single workflow."""
+
 CACHE_ENABLED = False
 """Determines if jobs caching is enabled."""
 

reana_job_controller/factory.py

@@ -48,7 +48,6 @@ def create_app(config_mapping=None):
     """Create REANA-Job-Controller application."""
     logging.basicConfig(level=REANA_LOG_LEVEL, format=REANA_LOG_FORMAT)
     app = Flask(__name__)
-    app.secret_key = "mega secret key"
     app.session = Session
     app.config.from_object(config)
     if config_mapping: