fs.copyFile not working with docker volumes

[crisward]

• Version:v10.4.1 (but seems to apply to any version of node using copyFile, tried 8.11 too)
• Platform: Linux 9c6e47477060 3.13.0-86-generic # 131-Ubuntu SMP Thu May 12 23:33:13 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux (inside docker container)
• Subsystem: filesystem / fs

require("fs").copyFile("/somevolume/text.txt","/somevolume/text2.txt",(err)=>{console.log(err)})

Expected behaviour - it copies the file
Actual behaviour - it fails to copy but no error is reported. This is not a file permissions issue as the command line cp command works as the same user. Also if the destination exists, it gets deleted, but the overwriting file doesn't get written.

The above code works if the files are not on a docker volume. The old method using createReadStream and createWriteStream also works.

The docker image I am using is the heroku buildpack. https://github.com/heroku/heroku-buildpack-nodejs. (with dokku)

[addaleax]

@nodejs/fs @nodejs/libuv

[santigimeno]

@crisward it's working for me with the official node docker image (v10.4.1).

[crisward]

@santigimeno Thanks for checking, I'll dig further and see what underlying docker image actually gets pulled.

[crisward]

Are there any specific dependencies that copyFile would use, that I could check for inside the container (dynamic libs perhaps)?

I'm not sure where to go with this, if it's a heroku buildpack issues I could open something there, or it may be something I need add to herokuish. Perhaps knowing about missing dependencies would help.

[santigimeno]

@crisward I don't know if it's possible for you to run that code with strace (strace -f node script.js) and post the output somewhere. (You'll need to run the container with --cap-add SYS_PTRACE)

[crisward]

Hope this helps.

https://gist.github.com/crisward/254896e0df574217dc70b9479dfbea70

[cjihrig]

It looks like fchmod() is failing: fchmod(11, 0100666) = -1 EPERM (Operation not permitted)

[santigimeno]

Yeah, but from the original comment it seems the error is not reported

[crisward]

That's correct, the error comes back null.

[cjihrig]

Figured it out. PR for libuv coming...