next-i18next deployed in AWS CloudFront traces error ENOENT: no such file or directory, scandir '/var/task/public/static/'

Question

and this uses next-i18next module. In my local server this works fine! for a multilang app. The problem is when I deployed this app to CloudFront as a serverless app. In my CloudWatch logs I can see:

da9949dd-1822-4d5c-b0d3-aeb56b6468ee    ERROR   Invoke Error    
{
    "errorType": "Error",
    "errorMessage": "ENOENT: no such file or directory, scandir '/var/task/public/static/locales/es'",
    "code": "ENOENT",
    "errno": -2,
    "syscall": "scandir",
    "path": "/var/task/public/static/locales/es",
    "stack": [
        "Error: ENOENT: no such file or directory, scandir '/var/task/public/static/locales/es'",
        "    at Object.readdirSync (fs.js:955:3)",
        "    at getAllNamespaces (/var/task/pages/index.js:53691:19)",
        "    at createConfig (/var/task/pages/index.js:53696:27)",
        "    at new NextI18Next (/var/task/pages/index.js:66340:48)",
        "    at Object.k7Sn (/var/task/pages/index.js:54121:18)",
        "    at __webpack_require__ (/var/task/pages/index.js:31:31)",
        "    at Module.IlR1 (/var/task/pages/index.js:24470:12)",
        "    at __webpack_require__ (/var/task/pages/index.js:31:31)",
        "    at Module.NIeY (/var/task/pages/index.js:27944:17)",
        "    at __webpack_require__ (/var/task/pages/index.js:31:31)"
    ]
}

2020-10-23T18:56:15.679Z da9949dd-182

My i18n.js is like this:

const NextI18Next = require('next-i18next').default
const { localeSubPaths } = require('next/config').default().publicRuntimeConfig
const path = require('path')
path.resolve('./public/static/locales');

module.exports = new NextI18Next({
  otherLanguages: ['en'],
  localeSubPaths,
  defaultLanguage: process.env.NEXT_PUBLIC_MAIN_LANG, 
  localePath: path.resolve('./public/static/locales')
}) 

My next.config.js file is like this:

const withSass = require("@zeit/next-sass");

const localeCountries = [
     { label: 'es', name: 'España', lang: 'es' },
     { label: 'uk', name: 'United Kingdom', lang: 'en' },
     { label: 'mx', name: 'México', lang: 'es' }
];
const localeSubPaths = {
     es: 'es',
     en: 'en'
};
// Extend your Next config for advanced behavior
// See https://nextjs.org/docs/api-reference/next.config.js/introduction
let nextConfig = {
     serverRuntimeConfig: {
          PROJECT_ROOT: __dirname
     },
     publicRuntimeConfig: {
          localeCountries,
          staticFolder: '/static', 
     }
};

// Add the Next SASS plugin
nextConfig = withSass(nextConfig);

module.exports = nextConfig;

Any help please? How to avoid this error?

**ENOENT: no such file or directory, scandir '/var/task/public/static/locales/es**

Answer 1

Your /public/static/locales/es files are not added to your default-lambda function source code. Presuming that you are using the @sls-next/serverless-component serverless component to deploy your Next.js infra, I had the same issue. I solved it with help from @dphang on the GitHub repo issues. postBuildCommands are now supported in the serverless.yml inputs. These will run after building your app and before deploying it. Modify your code as follows:

serverless.yml

myNextApp:
  component: "@sls-next/[email protected]"
  inputs:
    timeout: 30
    build:
      postBuildCommands: ["node serverless-post-build.js"]
  memory: 1024

Add a post-build script to copy the files over:

serverless-post-build.js

// post-build.js
const fs = require("fs-extra");
console.log("-> Copying locales directory...");
// Path to locales directory
const localeSrc = "./static/locales";
// Path to default-lambda destination
const localeDest = "./.serverless_nextjs/default-lambda/static/locales";
// Copy Files over recursively
fs.copySync(localeSrc, localeDest, { recursive: true });
console.log("Locale directory was copied successfully");

You will need to edit the above script for your use case:

// post-build.js
const fs = require("fs-extra");
console.log("-> Copying locales directory...");
// Path to locales directory
const localeSrc = "./public/static/locales";
// Path to default-lambda destination
const localeDest = "./.serverless_nextjs/default-lambda/public/static/locales";
// Copy Files over recursively
fs.copySync(localeSrc, localeDest, { recursive: true });
console.log("Locale directory was copied successfully");