在Google Cloud上处理PDF功能：生成pdftotext ENOENT

Question

我正在尝试处理Google Cloud Functions上的PDF。但我认为它错过了一个包pdftotext。我怎样才能解决这个问题？

我有：

const extract = require('pdf-text-extract')

...
  const gcsBucket = gcs.bucket(bucket)
  const tempFilePath = path.join(os.tmpdir(), path.basename(name))

  return gcsBucket.file(name).download({
    destination: tempFilePath
  })
    .then(() => {
      return new Promise((resolve, reject) => {
        extract(tempFilePath, (err, pages) => { 
          if (err) return reject(err) // I think it fails here
          return resolve(pages)
        })
      })
    })

我得到了

Error: spawn pdftotext ENOENT
    at exports._errnoException (util.js:1020:11)
    at Process.ChildProcess._handle.onexit (internal/child_process.js:197:32)
    at onErrorNT (internal/child_process.js:376:16)
    at _combinedTickCallback (internal/process/next_tick.js:80:11)
    at process._tickDomainCallback (internal/process/next_tick.js:128:9)