Permission denied (os error 13) when writing to file from Dockerfile

[luPhz]

I setup a directory like in the example https://github.com/denoland/deno_docker/tree/main/example

the only content of main.ts is
await Deno.writeTextFile("hello.txt", "Hello World");
like in the deno examples.

running this on ubuntu
$ docker build -t app . && docker run -it -v ${PWD}:/app -p 1993:1993 app
lead to the error message

await Deno.writeTextFile("hello.txt", "Hello World");
^
    at async writeFile (ext:deno_fs/30_fs.js:805:7)
    at async file:///app/main.ts:1:1

Removing USER deno from the dockerfile works for the moment. What is going on here?

[irbull]

Not much to add other than I experienced this too. It's working fine in our production (linux) systems, but on my development machine (mac M1) this is failing to write (new) files. Writing to existing files seems to work ok.

[irbull]

In my case, the Dockerfile was copying in a directory with the same name as the directory I was trying to create / write to in Deno. The copy operation resulted in different permissions, and it failed to write. Of course, if I didn't user USER deno, then Docker defaults to USER root and this worked. Maybe not related to your problem.