Cannot set runtime config options in the `listen` hook

Environment

Nuxt CLI v3.0.0-27404337.c9c0171 23:24:46 RootDir: /Volumes/Samsung_T5/GitHub/mai-attire 23:24:47 Nuxt project info: 23:24:47

---

• Operating System: Darwin
• Node Version: v14.18.2
• Nuxt Version: 3.0.0-27404337.c9c0171
• Package Manager: yarn@1.22.17
• Bundler: Vite
• User Config: privateRuntimeConfig, buildModules, googleFonts, css, vite, ngrok
• Runtime Modules: -
• Build Modules: ~/modules/google-fonts, ~/modules/ngrok

---

Reproduction

nuxt.hook('listen', () => {
  const url = 'my.url.com'
  nuxt.options.publicRuntimeConfig.ngrok = { url };
})

import config from "#config";

export default class ServerMiddlewarUtils {
  constructor() {
    console.log("config", config);
  }
}

Describe the bug

When creating a module, the only way I can see to set the runtime configs is as shown above - this was also how modules used to do it as well such as the ngrok module.

The new value is not available when importing #config in server middleware.

Additional context

No response

Logs

No response

[lewebsimple]

Isn’t the listen hook only available in development mode ?

[danielroe]

By this point in the server lifecycle, we have already passed runtime configuration to nitro, so changing top-level items doesn’t take effect (but modifying nested objects should work fine): https://stackblitz.com/edit/github-bsr21s.

However, for a dev module, you should be careful not to set runtimeConfig at build-time or the configuration will persist into the built server. It’s also limited to things that can be serialized - so no functions in runtimeConfig, for example.

Finally, it’s also possible to add a template and access this within your serverMiddleware: https://stackblitz.com/edit/github-bsr21s-bf23tt.

Note: We should consider which of these options we recommend (if any) and document this in the module authors guide. cc: @pi0 @clemcode