labextension install fails when read-only template yarn.lock is copied into staging directory

[MMesch]

Description

jupyter labextension install myextension --app-dir=./myapp

fails with

error An unexpected error occurred: "EACCES: permission denied, open '/nix/store/lg2kmn1i3wj0473q0i6vbjbqhvrg5yky-jupyterlab-extended/staging/yarn.lock'"

when the template yarn.lock file that is included in the base jupyterlab package is readonly. In this case, it seems to be copied over to ./myapp when the staging directory is populated without setting the appropriate access rights:

jupyterlab/jupyterlab/commands.py

Line 1181 in 172e664

shutil.copy(lock_template, lock_path)

This naturally occurs when installing jupyterlab with Nix, where the base install has to be immutable to ensure reproducibility. A simple fix would be to set write access on the copied yarn.lock in the staging directory.

Reproduce

(I can only give approximate steps for a standard conda or pip install because I am using nix to install jupyterlab)

1. install jupyter lab and find the staging directory.
2. set chmod -w yarn.lock inside of the staging directory
3. go to a temporary directory somewhere else
4. run jupyter labextension install <<anyextension>> --app-dir=. --debug

Expected behavior

Jupyterlab with the extension is built successfully in app-dir.

Context

• Operating System and version: Ubuntu 16.04, Nix package manager
• JupyterLab version: 1.2.2

[jluttine]

I opened a PR for nixpkgs to fix it there. Perhaps the patch could be offered to Jupyter Lab too though.

NixOS/nixpkgs#118821

[jluttine]

Alright, PR opened: #10063

[blink1073]

Great, thanks @jluttine, I was just about to ask you to do that! 😄