ENOENT no such file on Express Endpoint for readFileSync

Question

I've been going slightly crazy trying to figure this out. I have some certs that I need to pass through to an authentication client from my api; however, the application continues to throw ENOENT exceptions even though the file clearly exists within the same directory (I've fiddled with this to make sure). I'm using readFileSync, effectively doing the following:

key:    fs.readFileSync('./privateKey.pem'),

Strangely, if I run this on a standalone Node server not as a part of an api, the file is able to be found without a problem. Is there some consideration I'm not aware of when trying to use readFileSync in such a scenario?

Thanks!

Answer 1

In node you need to be very careful with relative file paths. The only place where I'd ever really use them is in require('./_____') statements, where ./ to mean "relative to this file". However, require is kind of a special case because it is a function that node automatically creates per-file, so it knows the path of the current file.

In general, standard functions have no way of knowing the directory containing the script that happened to call a function, so in almost all cases, ./ means relative to the current working directory (the directory you were in when you ran node <scriptname>.js). The only time that is not the case is if your script or a module you use explicitly calls process.chdir to set the working directory to something else. The correct way to reference files relative to the current script file is to explicitly use an absolute path by using __dirname + '/file.js'.