How to configure firefox to use adobe flash on nixos

Question

I am trying to configure nixos' firefox to use adobe flash.

I am well aware of the issues of adobe flash; I "need" it (on one specific host) because of school games played by my son.

It is clear that nixos' firefox is intended to be able to use adobeFlash; the package is set to be configurable here. However, despite searching in the nixos manual, even an oblique reference here and various other websearches, I cannot find how to pass the required configuration to firefox.

Any help much appreciated.

Answer 1

Here is what I have in my ~./nixpkgs/config.nix to enable Adobe Flash Player plugin in Firefox installed into my user profile (with nix-env -iA nixos.firefox):

{
  allowUnfree = true;

  firefox = {
    enableAdobeFlash = true;
    # ...
  };

  # ...
}

It think I found this solution either in the official documentation or in the wiki, but now I can only find it in the wiki for Chromium.

Note however that since almost a week ago I cannot upgrade my Firefox to the latest version on NixOS stable (19.03) because of missing Flash Player plugin dependency:

curl: (22) The requested URL returned error: 404 Not Found
error: cannot download flash_player_npapi_linux.x86_64.tar.gz from any mirror
builder for '/nix/store/0g1cfkpa707356f6yic66q16sf4sc6n0-flash_player_npapi_linux.x86_64.tar.gz.drv' failed with exit code 1
cannot build derivation '/nix/store/ybdw3hfpwir3sc709wcg1lpqhm6yph3l-flashplayer-32.0.0.207.drv': 1 dependencies couldn't be built
cannot build derivation '/nix/store/zdxk4jw97xfmqaib1clqwwbc7p721zlf-firefox-68.0esr.drv': 1 dependencies couldn't be built
error: build of '/nix/store/zdxk4jw97xfmqaib1clqwwbc7p721zlf-firefox-68.0esr.drv' failed

This seems to be a known issue that happens when Adobe releases a new version of the Flash Player NPAPI plugin and deletes the old version from their server.