feat: Allow custom resources path via environment variable

[FelixLusseau]

Hi

As a long time user of the Deezer-Desktop app with the Ubuntu .deb and my own NixOS derivation, I tried to publish it on Nixpkgs NixOS/nixpkgs#488329.
A Nix derivation is a wrapper to build an app from source or prebuilded packages for Nix packages manager and NixOS users. For deezer-linux, it only consists to put the files in the right place from the .tar.xz releases.

One of the maintainers suggested NixOS/nixpkgs#488329 (review) to use the Nixpkgs packaged Electron instead of the deezer-linux one to reduce the derivation complexity, keep Electron up-to-date and mainly to not rebuild and patch the included Electron to make it working on NixOS (because of the linker differences).

So I made it and I encountered an issue. The default process.resourcesPath is Electron one and not the folder packaged in the .tar.xz so the app is crashing at startup because it is not finding the systray.png icon.

❯ deezer-desktop
13:47:27.399 › Init App
(node:138859) UnhandledPromiseRejectionWarning: Error: Failed to load image from path '/nix/store/6ppl38w30hiygnhzkxagm6yrw9jdl15x-electron-unwrapped-38.7.2/libexec/electron/resources/linux/systray.png'
    at TrayService.init (/nix/store/ffxw5dysivcsw0y18fysxl255rkjyjdq-deezer-desktop-7.1.70/share/deezer-desktop/resources/app.asar/build/main.js:2246:25)
    at Object.<anonymous> (/nix/store/ffxw5dysivcsw0y18fysxl255rkjyjdq-deezer-desktop-7.1.70/share/deezer-desktop/resources/app.asar/build/main.js:2934:25)
    at Generator.next (<anonymous>)
    at fulfilled (/nix/store/ffxw5dysivcsw0y18fysxl255rkjyjdq-deezer-desktop-7.1.70/share/deezer-desktop/resources/app.asar/build/main.js:2836:26)
(Use `electron --trace-warnings ...` to show where the warning was created)
(node:138859) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
^C

The only solution is to edit the app.asar because NixOS packages are readonly so it is not possible to edit Electron to symlink the file without rebuilding it (and go back to a similar of the initial derivation).

So I created a patch to the original app here to add the optional possibility to override the process.resourcesPath when loading the systray icon whithout breaking Deezer.

I tested it and it is solving the error.

If this patch is accepted and my Nixpkgs derivation PR too, the app will then be available on Nixpkgs for all NixOS users with your credits (because it is just a wrap) with the command nix-shell -p deezer-desktop or by adding it to their NixOS configuration.nix or Nix Flakes.

Thank you for your time and feel free to make suggestions on this PR if needed.

[josselinonduty]

Tiny detail, I think it would be better to name the patch "override-resources-path"
Otherwise, LGTM

[josselinonduty]

Hey,

The content of the patch looks good to me; I am not familiar with nix-related stuff but it seems to be a reasonable approach to solve your upstream issue.

[FelixLusseau]

Hi

Thank you for the feedback. I renamed the patch.

Finally, to build the Nix package, I only use the asar, the systray.png, the svg and the .desktop.

Maybe, could it be possible to publish an additional .tar.xz with only that on releases ?

[FelixLusseau]

Thank you for the approval and merge too 🙏

[josselinonduty]

I am waiting for an upstream deezer update to create a release (with your patch). it usually takes 1 or 2 weeks