Active Record Session Store

A session store backed by an Active Record class. A default class is provided, but any object duck-typing to an Active Record Session class with text session_id and data attributes is sufficient.

Installation

Include this gem into your Gemfile:

gem 'activerecord-session_store'

Run the migration generator:

rails generate active_record:session_migration

Run the migration:

rake db:migrate

Then, set your session store in config/initializers/session_store.rb:

Rails.application.config.session_store :active_record_store, :key => '_my_app_session'

To avoid your sessions table expanding without limit as it will store expired and potentially sensitive session data, it is strongly recommended in production environments to schedule the db:sessions:trim rake task to run daily. Running bin/rake db:sessions:trim will delete all sessions that have not been updated in the last 30 days. The 30 days cutoff can be changed using the SESSION_DAYS_TRIM_THRESHOLD environment variable.

Configuration

The default assumes a sessions tables with columns:

• id (numeric primary key),
• session_id (string, usually varchar; maximum length is 255), and
• data (text, longtext, json or jsonb); careful if your session data exceeds 65KB).

The session_id column should always be indexed for speedy lookups. Session data is marshaled to the data column in Base64 format. If the data you write is larger than the column's size limit, ActionController::SessionOverflowError will be raised.

You may configure the table name, primary key, data column, and serializer type. For example, at the end of config/application.rb:

ActiveRecord::SessionStore::Session.table_name = 'legacy_session_table'
ActiveRecord::SessionStore::Session.primary_key = 'session_id'
ActiveRecord::SessionStore::Session.data_column_name = 'legacy_session_data'
ActiveRecord::SessionStore::Session.serializer = :json

Note that setting the primary key to the session_id frees you from having a separate id column if you don't want it. However, you must set session.model.id = session.session_id by hand! A before filter on ApplicationController is a good place.

The serializer may be class responding to #load(value) and #dump(value), or a symbol of marshal, json, hybrid or null. marshal is the default and uses the built-in Marshal methods coupled with Base64 encoding. json does what it says on the tin, using the parse() and generate() methods of the JSON module. hybrid will read either type but write as JSON. null will not perform serialization, leaving that up to the ActiveRecord database adapter. This allows you to take advantage of the native JSON capabilities of your database.

Since the default class is a simple Active Record, you get timestamps for free if you add created_at and updated_at datetime columns to the sessions table, making periodic session expiration a snap.

You may provide your own session class implementation, whether a feature-packed Active Record or a bare-metal high-performance SQL store, by setting

ActionDispatch::Session::ActiveRecordStore.session_class = MySessionClass

You must implement these methods:

• self.find_by_session_id(session_id)
• initialize(hash_of_session_id_and_data, options_hash = {})
• attr_reader :session_id
• attr_accessor :data
• save
• destroy

The example SqlBypass class is a generic SQL session store. You may use it as a basis for high-performance database-specific stores.

Please note that you will need to manually include the silencer module to your custom logger if you are using a logger other than Logger and Syslog::Logger and their subclasses:

MyLogger.send :include, ActiveRecord::SessionStore::Extension::LoggerSilencer

This silencer is being used to silence the logger and not leaking private information into the log, and it is required for security reason.

CVE-2019-25025 mitigation

Sessions that were created by Active Record Session Store version 1.x are affected by CVE-2019-25025. This means an attacker can perform a timing attack against the session IDs stored in the database.

After upgrade to version 2.0.0, you should run db:sessions:upgrade rake task to upgrade all existing session records in your database to the secured version.

$ rake db:sessions:upgrade

This rake task is idempotent and can be run multiple times, and session data of users will remain intact.

Please see #151 for more details.

Contributing to Active Record Session Store

Active Record Session Store is work of many contributors. You're encouraged to submit pull requests, propose features and discuss issues.

See CONTRIBUTING.

License

Active Record Session Store is released under the MIT License.