My setup:

"amazon-cognito-identity-js": "^6.3.13",
"aws-amplify": "^5.3.18",
"aws-amplify-react-native": "^7.0.8",
"expo": "~51.0.11",
"react-native": "0.74.2",

I have a React Native with Expo 51 project and I’m trying to “generate” my aws-exports.js file dynamically during my builds.

I’ve also created some EAS Secrets with my aws-exports.js file encoded in BASE64.

In order to have more flexibility in my builds I’ve overwriten the default eas-build-pre-install hook, so I could run some custom scripts in order to generate my file.

This is working as spected, the aws-exports.js file is created and handleEncodedFile is executed

"eas-build-pre-install": "touch ./src/aws-exports.js && node ./src/scripts/handleEncodedFile.scripts.js",

And here is my handleEncodedFile script:

const fs = require("node:fs");

function createAwsExports() {
  // defaults ENV VARs from EAS
  const buildProfile = process.env.EAS_BUILD_PROFILE;
  const workingDir = process.env.EAS_BUILD_WORKINGDIR;

  try {
    console.info("Using EAS Build Profile: ", buildProfile);
    console.info("Running from DIR: ", workingDir);

    let handleDecodedSecret = null;

    switch (buildProfile) {
      case "development":
        const expoDevSecret = process.env.AWS_EXPORTS_DEV;
        handleDecodedSecret = Buffer.from(expoDevSecret, "base64").toString();
        break;
      case "production":
        const expoPrdSecret = process.env.AWS_EXPORTS_PRD;
        handleDecodedSecret = Buffer.from(expoPrdSecret, "base64").toString();
        break;
      default:
        throw new Error("Unknown build profile: ", buildProfile);
    }

    if (!handleDecodedSecret) {
      throw new Error(
        '"handleDecodedSecret" is NULL. This should never happen'
      );
    }

    // returns TRUE
    console.log(
      'Does "src/aws-exports.js" exists? ',
      fs.existsSync(`${workingDir}/src/aws-exports.js`)
    );

    // Execution stops here
    fs.writeFile(`${workingDir}/src/aws-exports.js`, handleDecodedSecret);
  } catch (error) {
    throw new Error('Error while creating "aws-exports.js": ', error);
  }
}

createAwsExports();

And this is the error I’m getting from Expo Dashboard (not very helpful tbh)

Script 'eas-build-pre-install' is present in package.json, running it...
Fri, 07 Jun 2024 02:04:58 GMT

> <my-app>@1.0.0 eas-build-pre-install

> touch ./src/aws-exports.js && node ./src/scripts/handleEncodedFile.scripts.js

Using EAS Build Profile:  development

Running from DIR:  /home/expo/workingdir/build

Does "src/aws-exports.js" exists?  true

/home/expo/workingdir/build/src/scripts/handleEncodedFile.scripts.js:46

    throw new Error('Error while creating "aws-exports.js": ', error);

          ^

Error: Error while creating "aws-exports.js": 

    at createAwsExports (/home/expo/workingdir/build/src/scripts/handleEncodedFile.scripts.js:46:11)

    at Object.<anonymous> (/home/expo/workingdir/build/src/scripts/handleEncodedFile.scripts.js:50:1)

    at Module._compile (node:internal/modules/cjs/loader:1256:14)

    at Module._extensions..js (node:internal/modules/cjs/loader:1310:10)

    at Module.load (node:internal/modules/cjs/loader:1119:32)

    at Module._load (node:internal/modules/cjs/loader:960:12)

    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:86:12)

    at node:internal/main/run_main_module:23:47

Node.js v18.18.0

npm run eas-build-pre-install exited with non-zero code: 1

The scripts above should:

1. Create an empty aws-exports.js in the expo workingdir /home/expo/workingdir/build/src
2. Validate which eas profile the build is running on and use the respective EAS Secret

In previous projects I’m using the following script in my package.json

// I always need to alter manually from AWS_EXPORTS_PRD to AWS_EXPORTS_DEV depending on the build
"eas-build-pre-install": "echo $AWS_EXPORTS_PRD | base64 -d -i > ./src/aws-exports.js"

It doesn’t break, but also doesn’t work. For some reason the only way I’ve got it working was removing it from the .gitignore, which I’m sick of doing.

Thansk for the help in advance!