CasperJS and AWS Lambda

Question

I'm trying to get casperjs to work with my AWS Lambda function.

{
"errorMessage": "Cannot find module 'casper'",
"errorType": "Error",
"stackTrace": [
"Function.Module._load (module.js:276:25)",
"Module.require (module.js:353:17)",
"require (internal/module.js:12:17)",
"Object.<anonymous> (/var/task/index.js:3:14)",
"Module._compile (module.js:409:26)",
"Object.Module._extensions..js (module.js:416:10)",
"Module.load (module.js:343:32)",
"Function.Module._load (module.js:300:12)",
"Module.require (module.js:353:17)"
]
}

I keep getting this error where Lambda can't detect casperjs. I uploaded my zip file into Lambda, and installed the casperjs modules into my directory before I zipped the files up.

My package.json file says I have casperjs installed.

{
"name": "lambda",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1"
},
"keywords": [],
"author": "",
"license": "ISC",
"dependencies": {
"casperjs": "^1.1.3",
} 
}

Would anyone know what I'm doing wrong? Thanks.

Answer 1

Since CasperJs relies on PhantomJs, you can set it up very similarly to this repo: https://github.com/TylerPachal/lambda-node-phantom.

The main difference being that you need to add and target CasperJs and you need to make sure that CasperJs can find and load PhantomJs.

1. Create a node_modules directory in your package directory.

2. Add a dependency for CasperJs to the packages.json file:

   "dependencies": {
       "casperjs": "latest"
   }
   

3. In Terminal, navigate to your package directory and run 'npm update' to add the CasperJs package to the node_modules directory.

4. Assuming that you want to run CasperJs with the 'test' argument, the index.js file will need to be changed to look like this:

   var childProcess = require('child_process');
   var path = require('path');
   
   exports.handler = function(event, context) {
   
       // Set the path as described here: https://aws.amazon.com/blogs/compute/running-executables-in-aws-lambda/
       process.env['PATH'] = process.env['PATH'] + ':' + process.env['LAMBDA_TASK_ROOT'];
   
       // Set the path to casperjs
       var casperPath = path.join(__dirname, 'node_modules/casperjs/bin/casperjs');
   
       // Arguments for the casper script
       var processArgs = [
           'test',
           path.join(__dirname, 'casper_test_file.js')
       ];
   
       // Launch the child process
       childProcess.execFile(casperPath, processArgs, function(error, stdout, stderr) {
           if (error) {
               context.fail(error);
               return;
           }
           if (stderr) {
               context.fail(error);
               return;
           }
           context.succeed(stdout);
       });
   }
   

   If you don't want to run CasperJs with the 'test' argument, just remove it from the arguments list.

5. The PhantomJs binary in the root directory of your package needs to be renamed to phantomjs, so that CasperJs can find it. If you would like to get a new version of PhantomJs, you can get one here: https://bitbucket.org/ariya/phantomjs/downloads. Make sure to download a linux-x86_64.tar.bz2 type so that it can run in Lambda. Once downloaded, just pull a new binary out of the bin directory and place it in your root package directory.

6. In order for Lambda to have permission to access all the files, it's easiest to zip the package in a Unix-like operating system. Make sure that all the files in the package have read and execute permissions. From within the package directory: chmod -R o+rx *. Then zip it up with: zip -r my_package.zip *.

7. Upload the zipped package to your Lambda function.