Language translation with S3 and AWS Translate

index.js

/* 

MIT No Attribution

Permission is hereby granted, free of charge, to any person obtaining a copy of this
software and associated documentation files (the "Software"), to deal in the Software
without restriction, including without limitation the rights to use, copy, modify,
merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Written by James Beswick (@jbesw) - contact if you have any questions!

*/

const AWS = require('aws-sdk')
AWS.config.region = process.env.AWS_REGION

const s3 = new AWS.S3()
const translate = new AWS.Translate()

// Entire list of language codes at: https://docs.aws.amazon.com/translate/latest/dg/API_TranslateText.html
const targetLanguages = ['fr', 'de', 'it', 'es', 'sv', 'ar', 'pt', 'ru']

// The standard Lambda handler
exports.handler = async (event) => {

    // Don't fire for objects in the translations folder
    if (event.Records[0].s3.object.key.indexOf('translations') > -1) return

    // Process for each object in the incoming event 
    await Promise.all(
        targetLanguages.map(async (targetLanguage) => {
            await doTranslation(event, targetLanguage)
        })
    )

    return {
        statusCode: 200,
        body: JSON.stringify('OK'),
    }
}

// The translation function
const doTranslation = async (event, targetLanguage) => {
    return new Promise(async (resolve, reject) => {
        
        // Get original text from object in incoming event
        const originalText = await getS3object({
            Bucket: event.Records[0].s3.bucket.name,
            Key: event.Records[0].s3.object.key
        })
    
        // Translate the text
        const data = await translateText(originalText.Body.toString('utf-8'), targetLanguage)

        // Save the new translation
        const baseObjectName = event.Records[0].s3.object.key.replace('.txt','')
        await putS3object({
            Bucket: event.Records[0].s3.bucket.name,
            Key: `translations/${baseObjectName}-${targetLanguage}.txt`,
            Body: data.TranslatedText,
            ContentType: 'text/plain'
        })
        resolve()
    })
}

// Wrapper for AWS Translate functionality
const translateText = async (originalText, targetLanguageCode) => {
    return new Promise((resolve, reject) => {
        let params = {
            Text: originalText,
            SourceLanguageCode: "auto",
            TargetLanguageCode: targetLanguageCode
        }
    
        try {
            translate.translateText(params, (err, data) => {
                if (err) {
                    console.log('translateText error: ', err)
                    reject(err)
                }

                console.log('translateText data: ', data)
                if (data) resolve(data)
            })
        } catch (err) {
            console.error(err)
        }
    })
}

// Returns object from S3
const getS3object = async function (params) {
  return new Promise((resolve, reject) => {
    s3.getObject(params, function(err, data) {
      if (err) {
        console.error('getS3object error: ', err, err.stack)
        reject(err)
      } 
      resolve (data)
    })
  })
}

// Puts object to S3 //
const putS3object = async function (params) {
  return new Promise((resolve, reject) => {
    s3.putObject(params, function(err, data) {
      if (err) {
        console.error('putS3object error: ', err, err.stack) 
        reject(err)
      } 
      resolve (data)
    })
  })
}