downloadAndRunVips.js

// AWS Lamda Function to Test Dynamic VIPS Binary
var exec = require('child_process').exec;
var spawn = require('child_process').spawn;
var https = require('https');

// Example Event:
// {
//   "cmd": "/tmp/vips/bin/vips -v",
//   "url": "https://www.dropbox.com/s/nba1piz7wfx2wb0/vips-8.3.0-0a4991c-dynamic.tar.bz2?dl=1"
// }
exports.handler = function(event, context) {
    if (!event.url) {
        context.fail('Please specify a vips tarball url as event.url');
        return;
    }
    if (!event.cmd) {
        context.fail('Please specify a command to run as event.cmd');
        return;
    }

    var tar = spawn('/bin/tar', ['xjC', '/tmp']);
    tar.stdout.on('data', console.log);
    tar.stderr.on('data', console.error);
    tar.on('exit', function(code) {
        if (code === 0) {
            console.log('Starting cmd ' + event.cmd);
            var child = exec(event.cmd, function(error) {
                // Resolve with result of process
                context.done(error, 'Process complete!');
            });

            // Log process stdout and stderr
            child.stdout.on('data', console.log);
            child.stderr.on('data', console.error);
        } else {
            context.fail('tar exited with error ' + code);
        }
    });

    var numRedirects = 0;
    var download = function(url) {
        console.log('Loading ' + url);
        https.get(url, function(resource) {
            if (resource.statusCode === 302) {
                var redirectUrl = resource.headers.location;
                if (numRedirects++ < 10) {
                    console.log('Following redirect to ' + redirectUrl);
                    download(redirectUrl);
                } else {
                    context.fail('Too many redirects: ' + numRedirects);
                }
            } else if (resource.statusCode === 200) {
                // Extract tar on the fly
                resource.pipe(tar.stdin);
                resource.on('error', function(error) {
                    console.error('Download failed!');
                    context.fail(error);
                });
                resource.on('end', function() {
                    console.log('Download finished!');
                    tar.stdin.end();
                });
            } else {
                context.fail('Unhandled http status code ', resource.statusCode);
            }
        }).on('error', function(error) {
            context.fail(error);
        });
   };
   download(event.url);
};

var context = {};
context.done = function(error, result) {
    if (error) {
        context.fail(error);
    } else {
        context.succeed(result);
    }
};
context.fail = function(error) {
    console.error(error);
    process.exit(1);
};
context.succeed = function(result) {
    console.log(result);
    process.exit(0);
};