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implementing using Redis as a session store in Rails 7 causing intermittent SessionStore::CookieOverflow errors

๐Ÿ‘€ Views: 59 ๐Ÿ’ฌ Answers: 1 ๐Ÿ“… Created: 2025-06-06
ruby rails redis sessions Ruby

I'm trying to implement Redis as a session store in my Rails 7 application, but I'm running into intermittent `SessionStore::CookieOverflow` errors. This seems to happen when the session size exceeds the maximum allowed by cookies, which is around 4KB. I've configured my session store in `config/initializers/session_store.rb` like this: ```ruby Rails.application.config.session_store :redis_store, servers: [ { host: "localhost", port: 6379, db: 0 }, ], key: "_my_app_session", expire_after: 90.minutes, threadsafe: false ``` I often store user preferences and shopping cart items in the session, which can add up quickly. Iโ€™ve tried to clear the session before storing new data to ensure it doesnโ€™t exceed the limit: ```ruby session.clear session[:cart] = @cart_items session[:user_preferences] = @user_preferences ``` However, this doesnโ€™t seem to consistently resolve the scenario, and I still see the behavior intermittently in production logs: ``` ActionDispatch::Cookies::CookieOverflow: Cookie overflow behavior: Session cookie too big. ``` I also noticed that when I inspect the session data, it sometimes contains unexpected entries, which might contribute to the overflow. I'm using the `redis` gem version 5.0.0 and `redis-rails` version 5.0.0. Any ideas on how to effectively manage session size or alternatively, configurations I might be missing? Is storing too much data in the session itself a bad practice? How can I ensure my application avoids these overflow errors? For context: I'm using Ruby on Linux.