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Add git-credential-helper with libsecret
added a more complex command to show how that can be added
 
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[https://en.wikipedia.org/wiki/Git_(software) Git] is the version control system (VCS) designed and developed by Linus Torvalds, the creator of the Linux kernel. Git is used to maintain NixOS packages, as well as many other projects, including sources for the Linux kernel.  
[https://en.wikipedia.org/wiki/Git_(software) Git] is the [[wikipedia:Version_control|version control system (VCS)]] developed by Junio C Hamano and designed by [[wikipedia:Linus_Torvalds|Linus Torvalds]] (Creator of the [[Linux kernel]]). Git is used to maintain NixOS packages, as well as many other projects, including sources for the Linux kernel.  


== Installation ==
== Installing and configuring Git ==


Install the <code>git</code> package.  
On NixOS, Git can be installed and configured at either the system level with the NixOS module or the user level with [[Home Manager]].


=== Additional features ===
=== System-wide installation ===


Install <code>tk</code> to use the git gui:
Git can be installed system-wide either by adding it to the list of system environment packages:
 
{{file|/etc/nixos/configuration.nix|nix|<nowiki>
environment.systemPackages = with pkgs; [
  git
];
</nowiki>}}
 
Or by enabling the NixOS Git module:
 
{{file|/etc/nixos/configuration.nix|nix|<nowiki>
programs.git.enable = true;
</nowiki>}}
 
Additional Git module configuration options can be found at {{nixos:option|programs.git}}.
 
{{note|Configuration options provided by this module are applied at the system level and therefore apply to all users on the system.}}
 
=== User-level configuration with Home Manager ===
 
Git can be configured using [[Home Manager]]:


<syntaxhighlight>
<syntaxhighlight lang="nix">
git citool
programs.git = {
  enable = true;
  settings.user = {
    name  = "John Doe";
    email = "johndoe@example.com";
  };
};
</syntaxhighlight>
</syntaxhighlight>


== Configuration ==
Aliases can be added with:
 
<syntaxhighlight lang="nix">programs.git = {
  enable = true;
  settings.alias = {
    ci = "commit";
    co = "checkout";
    s = "status";
    sync = "!git pull --rebase && git push";
  };
};</syntaxhighlight>


Git can be configured using [[Home Manager]]:
Git [https://git-lfs.com/ LFS] can be enabled with:


<syntaxhighlight lang="nix">
<syntaxhighlight lang="nix">
programs.git = {
  enable = true;
  lfs.enable = true;
};
</syntaxhighlight>
Configure git-credential-helper with <code>libsecret</code>:
<syntaxhighlight lang="nix">{ pkgs, ... }:
{
   programs.git = {
   programs.git = {
     enable = true;
     enable = true;
     userName  = "John Doe";
     package = pkgs.git.override { withLibsecret = true; };
     userEmail = "johndoe@example.com";
     settings = {
      credential.helper = "libsecret";
    };
   };
   };
</syntaxhighlight>
}</syntaxhighlight>
 
To add additional configuration you can specify options in an attribute set, so to add something like this:
 
<syntaxhighlight lang="ini">[push]
        autoSetupRemote = true</syntaxhighlight>


Configure git-credential-helper with libsecret:
To your <code>~/.config/git/config</code>, you can add the below to <code>settings</code>


<syntaxhighlight lang="nix">
<syntaxhighlight lang="nix">
Line 33: Line 86:
   programs.git = {
   programs.git = {
     enable = true;
     enable = true;
     extraConfig = {
     settings = {
       credential.helper = "${
       push = { autoSetupRemote = true; };
          pkgs.git.override { withLibsecret = true; }
    };
         }/bin/git-credential-libsecret";
  };
}
</syntaxhighlight>
 
==== Using your public SSH key as a signing key ====
 
To configure git to automatically sign your commits using your public SSH key like so:
 
<syntaxhighlight lang="nix">
{
  programs.git = {
    enable = true;
    signing = {
      key = "ssh-ed25519 AAAAAAAAAAAA...AA username@hostname";
      signByDefault = true;
    };
    settings = {
      gpg = {
         format = "ssh";
      };
     };
     };
   };
   };
}
}
</syntaxhighlight>
However, note that this will also require Home Manager to manage your SSH configuration:
<syntaxhighlight lang="nix">{   
  programs.ssh = {
    enable = true;
    addKeysToAgent = "yes";
  };
}</syntaxhighlight>
=== Enabling Git UI ===
Install <code>tk</code> to use the git gui:
<syntaxhighlight lang=console>
$ git citool
</syntaxhighlight>
Or you may wish to install the <code>gitFull</code> package, which includes <code>git gui</code>, <code>gitk</code>, etc. This can be installed either through system environment packages or by setting the package module option:
<syntaxhighlight lang="nix">
programs.git = {
  enable = true;
  package = pkgs.gitFull;
};
</syntaxhighlight>
</syntaxhighlight>


== Management of the <code>nixpkgs</code> git repository ==
== Management of the <code>nixpkgs</code> git repository ==


<code>nixpkgs</code> has become a git repository of quite substantial size with > 160 000 commits (as of early 2019). This brings many unoptimized tools to their limits, leading to long waiting times on certain operations. Here we’ll collect useful info on how to manage that.
<code>nixpkgs</code> has become a git repository of quite substantial size with > 1M commits<ref>https://github.com/NixOS/nixpkgs</ref> (as of 2026). This brings many unoptimized tools to their limits, leading to long waiting times on certain operations. Here we’ll collect useful info on how to manage that.


=== git ===
=== Garbage collecting ===


git itself might not perform as usual with the default settings
Normal <code>git gc</code> should work as usual, but you should force a full garbage collect every half a year or so. <code>git gc --aggressive</code> is the command for that. For the author it did not work on the first try, since their laptop’s memory was too small, and it went out of memory. According to [https://stackoverflow.com/a/4829883/1382925|this StackOverflow] answer it suffices to set some local repository config variables.


==== <code>git-gc</code> ====
<syntaxhighlight lang=console>
$ git config pack.windowMemory 2g
$ git config pack.packSizeLimit 1g
</syntaxhighlight>
 
This worked well on a machine with about 6–8 GB of free RAM and two processor threads, and reduced the size of the <code>nixpkgs</code> checkout from ~1.3 GB to ~0.95 GB.
 
= Serve Git repos via SSH =
 
This section implements [https://git-scm.com/book/en/v2/Git-on-the-Server-Setting-Up-the-Server Git on the Server - Setting Up the Server] on NixOS.
 
See also: [[gitolite]].
 
== Configuration ==
 
<syntaxhighlight lang="nix">
{ config, pkgs, ... }: {
  users.users.git = {
    isSystemUser = true;
    group = "git";
    home = "/var/lib/git-server";
    createHome = true;
    shell = "${pkgs.git}/bin/git-shell";
    openssh.authorizedKeys.keys = [
      # FIXME: Add pubkeys of authorized users
      "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIF38sHxXn/r7KzWL1BVCqcKqmZA/V76N/y5p52UQghw7 example"
    ];
  };
 
  users.groups.git = {};
 
  services.openssh = {
    enable = true;
    extraConfig = ''
      Match user git
        AllowTcpForwarding no
        AllowAgentForwarding no
        PasswordAuthentication no
        KbdInteractiveAuthentication no
        PermitTTY no
        X11Forwarding no
    '';
  };
}
</syntaxhighlight>
 
== Usage ==
 
1. Run this on the server to create repo <code>myproject</code> accessible by user <code>git</code>
 
<syntaxhighlight lang="console">
$ sudo -u git bash -c "git init --bare ~/myproject.git"
</syntaxhighlight>
(<code>~</code> here is the home of the user <code>git</code>, which is <code>/var/lib/git-server</code>)
 
2. Push to the server repo from another system
 
<syntaxhighlight lang="console">
$ mkdir myproject
$ cd myproject
$ echo "hello" > a
$ git init
$ git add .
$ git commit -m "init"
$ git remote add origin git@myserver:myproject.git
$ git push origin master
</syntaxhighlight>
 
3. Clone and edit the server repo from another system
 
<syntaxhighlight lang="console">
$ git clone git@myserver:myproject.git
$ cd myproject
$ cat a
$ echo "world" >> a
$ git commit -am "hello"
$ git push origin master
</syntaxhighlight>


Normal <code>git gc</code> should work as usual, but you should force a full garbage collect every half a year or so. <code>git gc --aggressive</code> is the command for that. For the author it did not work on the first try, since their laptop’s memory was too small and it went out of memory. According to [https://stackoverflow.com/a/4829883/1382925|this StackOverflow] answer it suffices to set some local repository config variables.
== Bisecting Nix regressions ==


git config pack.windowMemory 2g
{{main|bisecting}}
git config pack.packSizeLimit 1g


worked well on a machine with about 6–8 GB of free RAM and two processor threads, and reduced the size of the <code>nixpkgs</code> checkout from ~1.3 GB to ~0.95 GB.
[[Category:Applications]]
[[Category:CLI Applications]]
[[Category:Version control]]
Retrieved from "https://wiki.nixos.org/wiki/Git"