KrakenJS config middleware and Express 4 router middleware execution priority

Execution Priority

In KrakenJS 2.x, middleware declared in config/middleware.json is guaranteed to execute before any router-level middleware registered inside controllers. This is because KrakenJS follows a strict boot sequence where global configuration middleware is registered via app.use() before the application mounts the controllers and their respective Express 4 routers.

The Impact of Environment Overrides

Environment-specific configuration overrides (e.g., middleware.dev.json) do not alter the relative execution order between the config layer and the router layer. They only change which middleware is registered during the config phase. The sequence remains: Config Middleware → Router Middleware.

Configuration Merge Behavior

When a middleware key exists in both the base middleware.json and an environment-specific override file, KrakenJS performs a replacement rather than a deep merge. If the environment config defines the same key, the entire value (or array) associated with that key in the base config is discarded and replaced by the override value.

Verification Steps

To verify the execution order and override behavior in your specific environment, you can use the following methods:

• Log Sequencing: Place a console.log('Config Middleware') in a global middleware and a console.log('Router Middleware') in a controller's router. The config log will always appear first in the terminal.
• Stack Inspection: You can inspect the Express router stack at runtime to see the registration order:

  // Inside a controller or startup script
  console.log(app._router.stack.map(layer => layer.handle.name));

Assumptions and Constraints

This behavior assumes a standard KrakenJS 2.x installation using Express 4. It assumes that no custom boot-strapping logic has been added to the app.js or internal framework files to manually reorder the app.use() calls. Because KrakenJS does not provide a public API to reorder middleware once the boot sequence has started, the order is effectively immutable at runtime.

Diagnostic Detail Needed: Are you using any custom app.js modifications or third-party boot-sequence plugins that intercept the config/middleware.json loading process?