Cache Expensive Resources in Rules

Rules will reach end of life (EOL) on January 31, 2028.

As of October 16, 2023, Rules are no longer available in newly created tenants.
As of November 18, 2024, Rules are read-only. Active Rules still run, and you can enable or disable them and change their configuration values and secrets. You can’t edit their code in the Dashboard, the Management API, or tools that use it, such as the Auth0 CLI, Deploy CLI, Terraform, and Agent Skills.
After January 31, 2028, Rules stop running and are removed.

Use Actions to extend Auth0:

To learn more about Actions, read Understand How Auth0 Actions Work.
To migrate, read Migrate from Rules to Actions.

In Rules you can store expensive resources using the global object. The global object survives individual execution, so you can reuse things stored there instead of creating them every time a Rule is run. However, the Rules environment can be recycled at any time so your code must always check that global contains what you expect. This example shows how to use the global object to keep a MongoDB connection:

//If the db object is there, use it.
if (global.db){
  return query(global.db, callback);
}

//If not, get the db (mongodb in this case)
mongo('mongodb://user:pass@mymongoserver.com/my-db',  function (db){
  global.db = db;
  return query(db, callback);
});

//Do the actual work
function query(db, cb){
  // Do something with db
  ...
  return cb(null, user, context);
}

To learn more about using MongoDB, read the MongoDB Manual.