Make the session-mongodb.ttl a computed config value.

Author: dlongley

CHANGELOG.md

@@ -4,6 +4,12 @@
 
 ### Changed
 - Update to `connect-mongo@5`.
+- Make the `session-mongodb.ttl` config value default to a value computed
+  from `express.session.ttl`. This does not change the default of 30
+  minutes but it does allow the express session TTL to properly propagate
+  to the `MongoStore` session store instance w/o the need for setting
+  the `session-mongodb.ttl` configuration value independently. It can
+  still be set independently, overiding the computed value if desired.
 
 ## 6.0.0 - 2022-04-29
 

lib/config.js

@@ -1,10 +1,27 @@
 /*!
- * Copyright (c) 2012-2022 Digital Bazaar, Inc. All rights reserved.
+ * Copyright (c) 2012-2025 Digital Bazaar, Inc. All rights reserved.
  */
-import {config} from '@bedrock/core';
+import {config, util} from '@bedrock/core';
+import '@bedrock/express';
+
+const cc = util.config.main.computer();
 
 config['session-mongodb'] = {
-  collection: 'session',
-  // timeout is in seconds (time for session to live on the server)
-  ttl: 60 * 30
+  collection: 'session'
 };
+
+// create computed `ttl` property based on express config...
+
+// default to 30 minute TTL expressed in seconds
+const THIRTY_MINUTES = 60 * 30;
+
+// timeout is in seconds (time for session to live on the server)
+cc('session-mongodb.ttl', () => {
+  if(config.express?.session) {
+    // express session ttl is in milliseconds, convert to seconds
+    const {ttl = THIRTY_MINUTES * 1000} = config.express.session;
+    // round down to ensure session doesn't live beyond configured value
+    return Math.floor(ttl / 1000);
+  }
+  return THIRTY_MINUTES;
+});