https://aalvrz.me/tags/nodejs/ Recent content in nodejs on Andrés Álvarez Hugo -- gohugo.io en-us Tue, 21 Nov 2017 00:00:00 +0000 https://aalvrz.me/posts/building-an-ocr-service-with-tesseractjs-in-aws-lambda/ Tue, 21 Nov 2017 00:00:00 +0000 https://aalvrz.me/posts/building-an-ocr-service-with-tesseractjs-in-aws-lambda/ <p>The past few days I was trying to make <a href="https://github.com/naptha/tesseract.js">TesseractJS</a> work in <a href="https://aws.amazon.com/lambda/">AWS Lambda</a> so that I could do some OCR (Optical Character Recognition) on some images I had stored in an S3 bucket. However I am a bit new to NodeJS and I was running into some difficulties getting it to work in the Lambda environment. In this post I am going to go through some of these issues and how I solved them.</p> <p>TesseractJS is a OCR library written in pure JavaScript. It can recognize the text in images, as well as provide information about the location of the paragraphs, lines, and words in the document.</p> <p>We will be using a <strong>NodeJS 6.10</strong> runtime in AWS Lambda. And I will be deploying the service with <a href="https://claudiajs.com/">ClaudiaJS</a>.</p> <h2 id="downloading-the-tesseractjs-files">Downloading the TesseractJS Files</h2> <p>When running TesseractJS to recognize an image, TesseractJS will automatically begin downloading some files, which include tesseract language files, a core library file, and a worker file. These are all files that TesseractJS requires in order to correctly run.</p> <p>The problem occurs when trying to download these inside AWS Lambda, since Lambda only allows writing to the <code>/tmp/</code> directory, you will get an error like this in your logs:</p> <pre><code>Error: EROFS: read-only file system, open 'eng.traineddata' </code></pre>