Configuration Values

You can check and set the configuration values in frontend/Config.ts.

The table below describes the configuration values for the Lexicon Mobile App.

If there is a default value indicated, you do not need to set it.

Variable	Required	Notes	Default Value	Example Value(s)
discourseUrl	Yes	The url of the Discourse Server (must start with http or https)	-	https://discourse.myserver.com https://discourse.myserver.com:8080 https://discourse.myserver.com/subpath https://discourse.myserver.com:8080/subpath
inferDevelopmentHost	No	The flag (true / false) to override localhost with the host of the development machine	(empty)	true

The config object

In the Config.ts file, you'll find a config object that allows you to specify configuration values by scenario.

The two primary scenarios are:

• localDevelopment: when developing against the app locally. This configuration is also used as a fallback for an unknown build channel.
• buildChannels: used to define configuration by build channel when building the app with the EAS CLI.

Primarily, you'll only be concerned with configuring discourseUrl for each of these sections.

discourseUrl

caution

discourseUrl must always be specified, with or without a port number, and must always start with either http:// or https://.

discourseUrl is used to specify the URL of the Discourse.

Example

const config = {
  localDevelopment: {
    discourseUrl: 'http://localhost:4200',
  },
  buildChannels: {
    preview: {
      discourseUrl: 'https://preview.myserver.com',
    },
    production: {
      discourseUrl: 'https://discourse.myserver.com',
    },
  },
};

With this configuration above, the app will:

• point at http://localhost:4200 when you run the app using npm run start
• point at https://preview.myserver.com when you build the app using eas build --profile preview
• point at https://discourse.myserver.com when you build the app using eas build

discourseUrl also can include a subpath if desired:

const config = {
  localDevelopment: {
    discourseUrl: 'http://localhost:4200',
  },
  buildChannels: {
    preview: {
      discourseUrl: 'https://preview.myserver.com:8080/subpath',
    },
    production: {
      discourseUrl: 'https://discourse.myserver.com',
    },
  },
};

Different Behavior in Development

When running the app locally, if discourseUrl is set to http://localhost or http://127.0.0.1, it will automatically be replaced with http://10.0.2.2 when accessed from an Android device or emulator. This ensures the Android emulator can connect to the local development server hosted on your machine.

Note: This behavior applies only during local development for android and does not affect production builds.

This approach resolves the issue where localhost inside the Android emulator does not point to your development machine. This happens due to network isolation. Android emulators run in a virtualized environment, meaning they are isolated from the host system. The IP address localhost (or 127.0.0.1) inside the emulator points to the emulator itself, not the host machine.

If you are interested in more details about this, the implementation of this behavior is available in frontend/constants/app.ts.

This behavior of automatically overriding those values can be disabled, with inferDevelopmentHost, which is covered below.

inferDevelopmentHost

info

This flag is only valid under localDevelopment. It has no effect when used as part of buildChannels.

When in development, by default, the Lexicon Mobile App will check to see if discourseUrl is set to either http://localhost or http://127.0.0.1.

When detected, either of those values will be overwritten with http://10.0.2.2 if android.

For scenarios where this behavior is not desirable, inferDevelopmentHost can be used as a flag to disable this behavior. It can be disabled by specifying the value as false.

When set to false, this behavior of overriding discourseUrl with http://10.0.2.2 will no longer occur, and the original value will be passed through as-is.

const config = {
  localDevelopment: {
    discourseUrl: 'http://localhost:4200',
    inferDevelopmentHost: false,
  },
};