Installing Firefox 98 on NixOS

I had an issue with a web app on mobile and wasn’t sure what was wrong. So, I wanted to use the “remote debugging” feature of Firefox to troubleshoot. This means I need to connnect my Android phone via adb and then connect it with the Firefox Inspector. But, unfortunately, Firefox on my Android device is 97, and my NixOS Firefox version was 94. I assumed upgrading would be simple, but no.

I tried a variety of nix-env -qa firefox but could only see this:

$ nix-env -qa firefox  

Nothing newer than 94. :(

Then, I read about this repository from Mozilla which provides an “overlay” for NixOS that permits you to install Firefox nightly builds. I wasn’t sure what an overlay means, but I’m game!

The steps are:

  1. Clone a repo from Mozilla
  2. Create an overlay directory for NixOS if you don’t already have it.
  3. Symlink the firefox nix file.
  4. Enter it in nix-shell
  5. Run Firefox!

First, clone this:


$ mkdir ~/.config/nixpkgs/overlays  
$ cd ~/.config/nixpkgs/overlays/
$ ln -s ~/ixpkgs-mozilla/firefox-overlay.nix .
$ nix-shell -p latest.firefox-beta-bin  

these derivations will be built:  
building '/nix/store/h0v87dqs5bwag9xg1x0fkb3796ffmh16-check-firefox-signature.drv'...  
gpg: directory '/build/tmp.FlTQ0pdOXK/.gnupg' created  
gpg: keybox '/build/tmp.FlTQ0pdOXK/.gnupg/pubring.kbx' created  
gpg: key 61B7B526D98F0353: 24 signatures not checked due to missing keys  
gpg: /build/tmp.FlTQ0pdOXK/.gnupg/trustdb.gpg: trustdb created  
gpg: key 61B7B526D98F0353: public key "Mozilla Software Releases <[](>" imported  
gpg: Total number processed: 1  
gpg:               imported: 1  
gpg: no ultimately trusted keys found  
gpgv: can't allocate lock for '/build/tmp.FlTQ0pdOXK/.gnupg/pubring.kbx'  
gpgv: Signature made Tue Feb  8 22:34:13 2022 UTC  
gpgv:                using RSA key 4360FE2109C49763186F8E21EBE41E90F6F12F6D  
gpgv: Good signature from "Mozilla Software Releases <[](>"  
building '/nix/store/grj409fklnq4dxkrmr42n9m7gp1avf3c-firefox-98.0b2.tar.bz2.drv'...  
trying [](  
 % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current  
                                Dload  Upload   Total   Spent    Left  Speed  
100 74.4M  100 74.4M    0     0   995k      0  0:01:16  0:01:16 --:--:-- 1617k  
building '/nix/store/i87gr5lrl2lpi4k5kmg0v0p3j96an2gr-firefox-release-bin-unwrapped-98.0b2.drv'...  
unpacking sources  
unpacking source archive /nix/store/yvq8qrkmq9i0nxj8fr2ya9b3cgbbar37-firefox-98.0b2.tar.bz2  
source root is firefox  
setting SOURCE_DATE_EPOCH to timestamp 1644352711 of file firefox/omni.ja  
patching sources  
post-installation fixup  
rewriting symlink /nix/store/mpg0zr7bqn4vpsx9idjpvhb157kdmhm2-firefox-release-bin-unwrapped-98.0b2/lib to be relative to /nix/store/mpg0zr7bqn4vpsx9idjpvhb157kdmhm2-firefox-release-bin-unwrapped-98.0b2  
rewriting symlink /nix/store/mpg0zr7bqn4vpsx9idjpvhb157kdmhm2-firefox-release-bin-unwrapped-98.0b2/bin/firefox to be relative to /nix/store/mpg0zr7bqn4vpsx9idjpvhb157kdmhm2-firefox-release-bin-unwrapped-98.0b2  
patching script interpreter paths in /nix/store/mpg0zr7bqn4vpsx9idjpvhb157kdmhm2-firefox-release-bin-unwrapped-98.0b2  
checking for references to /build/ in /nix/store/mpg0zr7bqn4vpsx9idjpvhb157kdmhm2-firefox-release-bin-unwrapped-98.0b2...  
Wrapping link: '/nix/store/mpg0zr7bqn4vpsx9idjpvhb157kdmhm2-firefox-release-bin-unwrapped-98.0b2/bin/firefox'  
building '/nix/store/p5rsn0c4cizi546qjqczx3znnfv1m44h-firefox-bin-98.0b2.drv'...  

Once that is done, you can run firefox and it will be version 98!

Each time you run the shell command, it downloads a new build. I wish I could pin it, but I think this is getting the latest nightly each time?

Combined with this command I can get the adb tools:

nix-shell -p androidenv.androidPkgs_9_0.platform-tools  

Then, I can connect my Android phone and debug it in Chrome.

$ adb devices  
List of devices attached  
ZY22BNPPRV      device