Expo plugin support for Android App Links

[CodingItWrong]

Checklist

• I have looked into the Readme, Examples, and FAQ and have not found a suitable solution or answer.
• I have looked into the API documentation and have not found a suitable solution or answer.
• I have searched the issues and have not found a suitable solution or answer.
• I have searched the Auth0 Community forums and have not found a suitable solution or answer.
• I agree to the terms within the Auth0 Code of Conduct.

Describe the problem you'd like to have solved

When I switched my Expo app from using custom scheme callback URLs to HTTPS callback URLs, I was not able to use the official react-native-auth0 Expo config plugin to configure the manifestPlaceholders needed to get the domain recognized. I had to write and use a small custom Expo config plugin instead.

Describe the ideal solution

I would like the official react-native-auth0 Expo config plugin to support configuring manifestPlaceholders to allow using Android App Links for HTTPS post-sign-in redirects.

This would make it easier for other users of the library to use Android App Links, which are more secure.

Alternatives and current workarounds

I was able to write the following custom Expo config plugin in our project to populate the manifestPlaceholders:

const { withAppBuildGradle } = require("expo/config-plugins")

const withAuth0 = (config, options = {}) => {
  config = withCustomAppBuildGradle(config, options)
  return config
}

const withCustomAppBuildGradle = (config, options) => {
  return withAppBuildGradle(config, (config) => {
    config.modResults.contents = config.modResults.contents.replace(
      `minSdkVersion rootProject.ext.minSdkVersion`,
      `manifestPlaceholders = [auth0Domain: "${options.domain}", auth0Scheme: "https"]
          minSdkVersion rootProject.ext.minSdkVersion`,
    )

    return config
  })
}

module.exports = withAuth0

app.json:

["./plugins/withAuth0.js", { domain: "your.tenant.auth0.com" }]

Additional context

I had thought that using the config plugin like so would populate the manifestPlaceholders:

["react-native-auth0", { customScheme: "https", domain: "your.tenant.auth0.com" }]

Unfortunately, I did not see the manifestPlaceholders in the generated Android project, but I do see them when I run my custom plugin.

[subhankarmaiti]

Hi @CodingItWrong ,
In Android apps or React Native CLI projects, manifestPlaceholders are typically used during the build process to configure the RedirectActivity in the AndroidManifest.xml. However, with the react-native-auth0 Expo config plugin, this setup is handled automatically. This means manifestPlaceholders are no longer required, and removing them will still allow you to use Android App Links.

[CodingItWrong]

OK thanks, it sounds I was making some incorrect assumptions about implementation details around manifestPlaceholders.

Since Android App Links are expected to work, they don't seem to be working for me. I will shared details filing it as a separate issue instead. Thank you!