dalalsunil1986 / nixos-tutorial

one hour, hands-on

check out the cheat sheet

outline

• setup (5m)
• nix-env package management (10m)
• nix-shell isolated environments (10m)
• NixOS declarative operating system configuration
  • introduction (5m)
  • service (5m)
  • network (5m)
  • user (5m)
• conclusion (5m)

setup

• download and install VirtualBox
• download NixOS VirtualBox appliance, double click, launch VM
• log in with demo/demo
• open a terminal, eg. on the bottom left corner of the screen, click the Launcher button → Applications → System → Terminal
• try running the commands below

nix-env package management

• each user has a nix profile, pointing to the current user environment, that is a set of installed packages, managed via nix-env
• only trusted channels are used by default, so updating the package lists is the only operation requiring root.

update package list	sudo nix-channel --update
search	nix search hello	also try search.nixos.org/packages
install	nix-env -iA nixos.hello	run it with hello
uninstall	nix-env -e hello	running hello fails
rollback	nix-env --rollback	hello is back

nix-shell isolated environments

• start a shell in an environment with some packages available, and run some commands in it:
  • nix-shell -p toilet
    • toilet NixOS
    • Ctrl+D to exit nix-shell
    • toilet NixOS fails
• start a shell with packages and run a command in it:
  • nix-shell -p toilet --run 'toilet --gay hello'
• try a python example
• nix-shell on its own will load default.nix or shell.nix from the current directory, where you can define an environment for a project.

NixOS declarative operating system configuration

• edit /etc/nixos/configuration.nix
  • eg. add services.openssh.enable = true; before the last }
• nixos-rebuild switch to the new configuration
• nixos-option services.openssh.enable to see the option's current value and documentation
• find the option on search.nixos.org/options, click the result, click the link after "Declared in:" and see The Source
• nixos-rebuild switch --rollback to previous configuration

let's try a few configuration options:

service

• services.openssh.enable = true;
  • run ssh demo@localhost on the vm and log in with demo / demo
• nginx
  • go to http://localhost/status on the vm
• monit
  • go to http://localhost:2812 on the vm, log in with admin / monit

system

• system.autoUpgrade.enable = true;
  • don't forget to check the documentation search.nixos.org/options?query=autoupgrade
• environment.systemPackages = [ pkgs.vim pkgs.cmatrix ];
  • all users can run cmatrix

user

• user.nix normal user
• user-sudo.nix with sudo
• user-sshkey.nix with ssh public key authentication

network

• networking.hostName = "darkstar";
• networking.firewall.allowedTCPPorts = [ 22 80 8000 ];

conclusion

• declarative - say what you want, not how to get there
• safe (atomic, rollback, isolated, consistent, hash-checked)
• reliable (deterministic, reproducible)
• fast (lazy, hash-based store, binary cache)
• great for repeatable builds and declarative operating system configuration

learn more