Google Clould Functions deploy: EROFS: read-only file system

Question

I'm trying to deploy my api to Google Cloud Functions, and I'm getting this:

EROFS: read-only file system, mkdir '/user_code/uploads'

⚠  functions[post]: Deployment error. Function load error: 
    Code in file index.js can't be loaded. Is there a syntax error in your code? 
    Detailed stack trace: Error: EROFS: read-only file system, mkdir '/user_code/uploads'
    at Error (native)
    at Object.fs.mkdirSync (fs.js:932:18)
    at Function.sync (/user_code/node_modules/multer/node_modules/mkdirp/index.js:71:13)
    at new DiskStorage (/user_code/node_modules/multer/storage/disk.js:21:12)
    at module.exports (/user_code/node_modules/multer/storage/disk.js:65:10)
    at new Multer (/user_code/node_modules/multer/index.js:15:20)
    at multer (/user_code/node_modules/multer/index.js:95:12)
    at Object.<anonymous> (/user_code/api/user.js:105:46)
    at Module._compile (module.js:577:32)
    at Object.Module._extensions..js (module.js:586:10)

Answer 1

Everything in the Cloud Functions runtime is read-only except for os.tmpdir() (which is likely going to be /tmp, but you shouldn't assume that). If you have any code (in api/user.js for example) that attempt to write anywhere else, it'll error.