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Giskard's configuration

This is the configuration of my home server named Giskard. Its configuration is made with NixOS. I had it saved on the server as NixOS own manual recommends.

After reading Gabriel's NixOS in production post I finally knew how to obtain a bare functionality like NixOps, but without NixOps dependency and its "saved states". This a simple configuration for a single, bare metal, server and there's no metadata due to a cloud infrastructure being involved.

I copied Giskard's /etc/nixos/configuration.nix here and then condensed Gabriel's wisdom and that of others in the Makefile and default.nix sources. What's here?

  • A NixOS configuration that can be built locally and then pushed and installed into the designated server using ssh. A new profile generation is created in the process so that the server's configuration can be rolled back in case the new one isn't working properly.
  • The nixpkgs archive is pinned to a known release using NixOS' channel commit ash.
  • A command to query the built configuration.
  • Secrets and passwords protected using git crypt

How to use this repository

You will have to clone it, replace my server's configuration with yours and change the DEST variable inside the shell.nix. You will have also to update the commit hashes in shell.nix, have a look here.

Then to activate the commands run the following in a terminal:

$ source env.sh

This command will install Nix if it isn't installed already. In such case it will ask you for your password because it will need superuser privileges to create the /nix directory, where it will store its packages.

Then you will have the following commands at your disposal:

build

This command will:

  1. instantiate (i.e. evaluate the nix expression and generate the derivation) the (configuration) Nix expression in nixos.nix;
  2. copy it to the destination server;
  3. build the configuration on the same destination.
deploy

This command will perform the following actions:

  1. execute the build command;
  2. add a new profile's generation to the system profile, that way it can be rolled back if necessary;
  3. activate the new configuration.
print_option <dotted config option>

This command allows you to know the final value of a configuration option, much like NixOS own nixos-option command but instead looks up the value in the built configuration. If I want to know the value of the boot.kernel.sysctl option, I'll execute the following:

print_option boot.kernel.sysctl
➤➤ Printing config option "boot.kernel.sysctl"...
{ "fs.inotify.max_user_watches" = 524288; "fs.protected_hardlinks" = true; "fs.protected_symlinks" = true; "kernel.core_pattern" = "core"; "kernel.kptr_restrict" = 1; "kernel.poweroff_cmd" = "/nix/store/wpcfjs9wn6nq1fy8hma177dqd3p6813h-systemd-239/sbin/poweroff"; "kernel.printk" = 4; "kernel.yama.ptrace_scope" = 0; "net.core.somaxconn" = 1024; "net.ipv6.conf.all.disable_ipv6" = true; "net.ipv6.conf.all.forwarding" = false; "net.ipv6.conf.default.disable_ipv6" = true; }
clean
will delete the subproducts of build and deploy commands execution