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Creating a NixOS live CD/en: Difference between revisions

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== Motivation ==
== Motivation ==
Creating a modified NixOS LiveCD out of an existing working NixOS installation has a number of benefits:
Creating a modified NixOS LiveCD out of an existing working NixOS installation has a number of benefits:
* Ensures authenticity.
* Ensures authenticity.
* No need for internet access.
* No need for internet access.
* It is easy to add your own packages and configuration changes to the image.
* It is easy to add your own packages and configuration changes to the image.
== Building ==
== Building ==
Building minimal NixOS installation CD with the <code>nix-build</code> command by creating this <code>iso.nix</code>-file. In this example with [[Neovim]] preinstalled.  
Building minimal NixOS installation CD with the <code>nix-build</code> command by creating this <code>iso.nix</code>-file. In this example with [[Neovim]] preinstalled.  
<syntaxhighlight lang="nix">
<syntaxhighlight lang="nix">
{ config, pkgs, ... }:
{ config, pkgs, ... }:
Line 19: Line 26:
}
}
</syntaxhighlight>
</syntaxhighlight>
Build the image via:
Build the image via:
<syntaxhighlight lang="bash">
<syntaxhighlight lang="bash">
nix-build '<nixpkgs/nixos>' -A config.system.build.isoImage -I nixos-config=iso.nix
nix-build '<nixpkgs/nixos>' -A config.system.build.isoImage -I nixos-config=iso.nix
</syntaxhighlight>
</syntaxhighlight>
Alternatively, use Nix [[Flakes]] to generate a ISO installation image, using the <code>nixos-24.05</code> branch as nixpkgs source:
Alternatively, use Nix [[Flakes]] to generate a ISO installation image, using the <code>nixos-24.05</code> branch as nixpkgs source:
{{file|flake.nix|nix|<nowiki>
{{file|flake.nix|nix|<nowiki>
{
{
Line 29: Line 40:
   inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.05";
   inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.05";
   outputs = { self, nixpkgs }: {
   outputs = { self, nixpkgs }: {
    packages.x86_64-linux.default = self.nixosConfigurations.exampleIso.config.system.build.isoImage;
     nixosConfigurations = {
     nixosConfigurations = {
       exampleIso = nixpkgs.lib.nixosSystem {
       exampleIso = nixpkgs.lib.nixosSystem {
Line 43: Line 55:
}
}
</nowiki>}}
</nowiki>}}
The following commands will generate the iso-image:
The following commands will generate the iso-image:
<syntaxhighlight lang="console">
<syntaxhighlight lang="console">
# git init
 
# git add flake.nix
# nix build path:$PWD
# nix build .#nixosConfigurations.exampleIso.config.system.build.isoImage
</syntaxhighlight>
</syntaxhighlight>
The resulting image can be found in <code>result</code>:
The resulting image can be found in <code>result</code>:
<syntaxhighlight lang="console">
<syntaxhighlight lang="console">
$ ls result/iso/
$ ls result/iso/
nixos-24.05.20240721.63d37cc-x86_64-linux.iso
nixos-24.05.20240721.63d37cc-x86_64-linux.iso
</syntaxhighlight>
</syntaxhighlight>
=== Testing the image ===
=== Testing the image ===


To inspect the contents of the ISO image:
To inspect the contents of the ISO image:
<syntaxhighlight lang="console">
<syntaxhighlight lang="console">
$ mkdir mnt
$ mkdir mnt
Line 64: Line 81:
$ umount mnt
$ umount mnt
</syntaxhighlight>
</syntaxhighlight>
To boot the ISO image in an emulator:
To boot the ISO image in an emulator:
<syntaxhighlight lang="console">
<syntaxhighlight lang="console">
$ nix-shell -p qemu
$ nix-shell -p qemu
$ qemu-system-x86_64 -enable-kvm -m 256 -cdrom result/iso/nixos-*.iso
$ qemu-system-x86_64 -enable-kvm -m 256 -cdrom result/iso/nixos-*.iso
</syntaxhighlight>
</syntaxhighlight>
===SSH===
===SSH===
In your <tt>iso.nix</tt>:
In your <tt>iso.nix</tt>:
<syntaxhighlight lang="nix">
<syntaxhighlight lang="nix">
{
{
Line 82: Line 104:
}
}
</syntaxhighlight>
</syntaxhighlight>
===Static IP Address===
===Static IP Address===


Static IP addresses can be set in the image itself. This can be useful for VPS installation.
Static IP addresses can be set in the image itself. This can be useful for VPS installation.
<syntaxhighlight lang="nix">
 
<syntaxhighlight lang="nix" line="1">
{
{
   ...
   ...
   networking = {
   networking = {
     usePredictableInterfaceNames = false;
     usePredictableInterfaceNames = false;
     interfaces.eth0.ip4 = [{
     interfaces.eth0.ipv4.addresses = [{
       address = "64.137.201.46";
       address = "64.137.201.46";
       prefixLength = 24;
       prefixLength = 24;
Line 100: Line 124:
}
}
</syntaxhighlight>
</syntaxhighlight>
=== Building faster ===
=== Building faster ===
The build process is slow because of compression.
The build process is slow because of compression.


Here are some timings for <code>nix-build</code>:
Here are some timings for <code>nix-build</code>:
{| class="wikitable" style="margin:auto"
{| class="wikitable" style="margin:auto"
|+ Compression results
|+ Compression results
Line 117: Line 144:
| <code>xz -Xdict-size 100%</code> (default) || 450s || 43%
| <code>xz -Xdict-size 100%</code> (default) || 450s || 43%
|}
|}
See also: [https://gist.github.com/baryluk/70a99b5f26df4671378dd05afef97fce mksquashfs benchmarks]
See also: [https://gist.github.com/baryluk/70a99b5f26df4671378dd05afef97fce mksquashfs benchmarks]


If you don't care about file size, you can use a faster compression
If you don't care about file size, you can use a faster compression
by adding this to your <code>iso.nix</code>:
by adding this to your <code>iso.nix</code>:
<syntaxhighlight lang="nix">
<syntaxhighlight lang="nix">
{
{
Line 126: Line 155:
}
}
</syntaxhighlight>
</syntaxhighlight>
==See also==
==See also==
* [https://nixos.org/manual/nixos/stable/index.html#sec-building-image NixOS Manual: Building a NixOS (Live) ISO].
* [https://nixos.org/manual/nixos/stable/index.html#sec-building-image NixOS Manual: Building a NixOS (Live) ISO].
[[Category:NixOS]]
[[Category:NixOS]]
[[Category:Deployment]]
[[Category:Deployment]]
[[Category:Cookbook]]
[[Category:Cookbook]]
Retrieved from "https://wiki.nixos.org/wiki/Creating_a_NixOS_live_CD/en"