cannot get this 'convert' cloud functions command to run - firebase

Question

This firebase function should take a pdf in /test/testfile.pdf, convert it to grey and save it somewhere. I want to use this function in a more complicated process, but the exec('convert') is really not helping me.
The issue is the 'exec' command keeps failing. In the shell, the exact command line you see here is working:
convert -colorspace GRAY -density 300 test/testfile.pdf /tmp/out.pdf
The error in the logs is this:
{ ChildProcessError: Command failed: convert -colorspace GRAY -density 300 test/testfile.pdf /tmp/out.pdf convert: no images defined `/tmp/out.pdf' # error/convert.c/ConvertImageCommand/3210. `convert -colorspace GRAY -density 300 test/testfile.pdf /tmp/out.pdf\` (exited with error code 1) at callback (/user_code/node_modules/child-process-promise/lib/index.js:33:27) at ChildProcess.exithandler (child_process.js:205:5) at emitTwo (events.js:106:13) at ChildProcess.emit (events.js:191:7) at maybeClose (internal/child_process.js:920:16) at Process.ChildProcess._handle.onexit (internal/child_process.js:230:5) name: 'ChildProcessError', code: 1, childProcess: { ChildProcess: { [Function: ChildProcess] super_: [Object] }, fork: [Function], _forkChild: [Function], exec: [Function], execFile: [Function], spawn: [Function], spawnSync: [Function: spawnSync], execFileSync: [Function: execFileSync], execSync: [Function: execSync] }, stdout: '', stderr: 'convert: no images defined `/tmp/out.pdf\' # error/convert.c/ConvertImageCommand/3210.\n' }
This is the function:
const functions = require('firebase-functions');
const rp = require('request-promise');
const request = require('request');
const baseURL = "https://www.google.com/cloudprint/"
const exec = require('child-process-promise').exec;
const mkdirp = require('mkdirp-promise');
const path = require('path');
const os = require('os');
const fs = require('fs');
exports.convertPDF = functions.https.onRequest((req, res) => {
const tempLocalThumbFile = path.join(os.tmpdir(), "out.pdf");
try {
let tempLocalFile = "test/testfile.pdf"
exec('convert -colorspace GRAY -density 300 test/testfile.pdf '+tempLocalThumbFile).then((a) => {
console.log('Conversion created at', tempLocalThumbFile);
}, function (err) {
console.log(err)
})
} catch(err) {
console.log(err)
}
})
I am pretty stuck. How to get this convert to work in Firebase Functions?

Answer 1

Actually the problem is what has been stated by #Nivco: Cloud Functions are missing the ghostscript package. There is a feature request already asking for making ghostscript package available. You can go to the link and click on the start icon to get email notifications when there are some news.
There is another StackoverFlow thread where it is mentioned a workaround consisting on getting gs binaries on your own.