NixOS - Reproducible Linux Distribution built around systemd
#nixos
Rok Garbas, @garbas
systemd conf 2016
NixOS
Nix Expression language
nixpkgs
nixops
Nix
Hydra
Building a package A
Filesystem /usr
Packaging instructions
Filesystem /usr with package A
Building a package B
Filesystem /usr with package A
Packaging instructions
Filesystem /usr with package
A and B
"traditional" package managers
Building a package B
Packaging instructions
Filesystem
/nix/store/
<hash>-packageB/...
Nix
Building a package A
Packaging instructions
Filesystem
/nix/store/
<hash>-packageA/...
Why Nix
(build) Reproducability
Atomicity
Rollbacks
Complete dependency
Multi version
Nix Demo
System management methods
Divergent
Convergent
Congruent
Disk State
Time
Actual
Target
Disk State
Actual
Target
Time
Disk State
Time
Actual
Target
Building a
config A
Filesystem /etc
configuration options
Filesystem /etc with config A
Building a
config B
Filesystem /etc with config A
configuration options
Filesystem /etc with config
A and B
Looks familiar?
Configuration
Most problems and complexity comes from mutating the state (/usr, /etc, ...)
What if we take Nix and build ...
- linux kernel
- initrd
- bootloader
- init system
- configuration files
- packages
NixOS
Declarative configuration (1/5)
{
boot.loader.grub.device = "/dev/sda";
fileSystem."/".device = "/dev/sda1";
networking.hostname = "webserver";
networking.firewall.allowedTCPPorts = [ 80 443 ];
environment.systemPackages = with pkgs; [ htop vim ];
services.openssh.enable = true
services.nginx =
{ enable = true;
virtualHosts."service.example.com" =
{ forceSSL = true;
enableACME = true;
location."/".proxyPass = "....";
};
};
...
}Declarative configuration (2/5)
{
...
services.xserver.displayManager.kdm.enable = true;
services.xserver.desktopManager.kde4.enable = true;
#services.xserver.desktopManager.kde5.enable = true;
networking.networkmanager.enable = true
...
}Declarative configuration (3/5)
{
...
systemd.services."hello" = {
description = "Hello";
serviceConfig.Type = "oneshot";
serviceConfig.RemainAfterExit = true;
wantedBy = [ "multi-user.target" ];
script = ''
echo "hello"
'';
};
...
}Declarative configuration (4/5)
{
...
# lenovo t410
boot = {
kernelParams = [
# Kernel GPU Savings Options (NOTE i915 chipset only)
"drm.debug=0" "drm.vblankoffdelay=1" "i915.semaphores=1" "i915.modeset=1"
"i915.use_mmio_flip=1" "i915.powersave=1" "i915.enable_ips=1"
"i915.disable_power_well=1" "i915.enable_hangcheck=1"
"i915.enable_cmd_parser=1" "i915.fastboot=0" "i915.enable_ppgtt=1"
"i915.reset=0" "i915.lvds_use_ssc=0" "i915.enable_psr=0" "vblank_mode=0"
"i915.i915_enable_rc6=1"
];
blacklistedKernelModules = [
# Kernel GPU Savings Options (NOTE i915 chipset only)
"sierra_net" "cdc_mbim" "cdc_ncm" "btusb"
];
};
hardware.cpu.intel.updateMicrocode = true;
...
}https://github.com/NixOS/nixos-hardware
Declarative configuration (5/5)
{
...
containers.database =
{ config =
{ config, pkgs, ... }:
{ services.postgresql.enable = true;
services.postgresql.package = pkgs.postgresql92;
};
};
...
}Why NixOS?
- atomic upgrades
- rollback
- multi-user package management
- reproducible installations
NixOS demo
NixOS Community
~500 services
current release: 16.09 (happens today :P)
~900 contributors
~11k packages
~13k pull requests / ~4k issues
