Add :ttl configuration option

README.md

@@ -36,7 +36,8 @@ In your Rails app, throw in an initializer with the following contents:
 My::Application.config.session_store :redis_session_store, {
   key: 'your_session_key',
   redis: {
-    expire_after: 120.minutes,
+    expire_after: 120.minutes,  # cookie expiration
+    ttl: 120.minutes,           # Redis expiration, defaults to 'expire_after'
     key_prefix: 'myapp:session:',
     url: 'redis://host:12345/2',
   }

lib/redis-session-store.rb

@@ -115,7 +115,7 @@ def decode(data)
   end
 
   def set_session(env, sid, session_data, options = nil)
-    expiry = (options || env.fetch(ENV_SESSION_OPTIONS_KEY))[:expire_after]
+    expiry = get_expiry(env, options)
     if expiry
       redis.setex(prefixed(sid), expiry, encode(session_data))
     else
@@ -128,6 +128,11 @@ def set_session(env, sid, session_data, options = nil)
   end
   alias write_session set_session
 
+  def get_expiry(env, options)
+    session_storage_options = options || env.fetch(ENV_SESSION_OPTIONS_KEY, {})
+    session_storage_options[:ttl] || session_storage_options[:expire_after]
+  end
+
   def encode(session_data)
     serializer.dump(session_data)
   end

spec/redis_session_store_spec.rb

@@ -59,6 +59,29 @@
     end
   end
 
+  describe 'when configured with both :ttl and :expire_after' do
+    let(:ttl_seconds) { 60 * 120 }
+    let :options do
+      {
+        key: random_string,
+        secret: random_string,
+        redis: {
+          host: 'hosty.local',
+          port: 16_379,
+          db: 2,
+          key_prefix: 'myapp:session:',
+          ttl: ttl_seconds,
+          expire_after: nil
+        }
+      }
+    end
+
+    it 'assigns the :ttl option to @default_options' do
+      expect(default_options[:ttl]).to eq(ttl_seconds)
+      expect(default_options[:expire_after]).to be_nil
+    end
+  end
+
   describe 'when initializing with top-level redis options' do
     let :options do
       {