soopy.moe
1# tops and bottoms
2this document outlines things that i learned from various sources and some pure guesswork
3
4> To learn Nix is to learn to suffer, and to learn the way of numbing the pain
5— Cassie circa. 2023
6
7## overriding packages
8the pill confused me and i thought i had to make overlays to do overrides but no
9
10in packages (i.e. `environment.systemPackages`), just do
11```nix
12#-------8<-Snip-------
13environment = {
14 systemPackages = with pkgs; [
15 (discord.override {withOpenASAR = true;})
16 ()
17 ];
18};
19#-------Snip->8-------
20```
21
22This works as well
23```nix
24security.sudo.package = (pkgs.sudo.override {withInsults = true;});
25```
26
27## overlays
28overlays are useful when you want to refer to a package globally.
29
30the gist of overlays is as thus:
31
32> overlay is just `final: pref: {}` functions where dumbed down idea is
33> that you do pkg = prev.pkg.override and refer to everything else from
34> final
35>
36> idea is like final = prev // overlay(prev, final)
37> (it's a recursive definition)
38
39(poorly made) example overlays can be found [here](https://github.com/soopyc/nixos-config/blob/master/overlays/discord-canary.nix)
40
41currently in-use and slightly better overlays can be found in this repo! head over to /overlays to see them.
42
43*note: replace `self: super:` with `final: prev:` for consistency*
44
45*concept and content by \@natsukagami*
46
47## extra opts
48a way of passing additional options globally to modules is by using extraOpts.
49
50in nix flakes, this is accomplished by using `specialArgs` in `nixosSystem`.
51
52for example, check out this line in our flake.nix:
53
54https://github.com/soopyc/nix-on-koumakan/blob/492dfaa01808c2aa5dbb2d8223163e92bcef673b/flake.nix#L22-L28
55
56this avoids the horror of `import ../../../utils/bar.nix;`
57
58refer to [nixpkgs:nixos/lib/eval-config.nix] and [nixpkgs:lib/modules.nix#122] for more info
59
60*pointers by \@natsukagami*
61
62## @ (at) syntax
63very simple.
64
65```nix
66args@{a, b, c, ...}: {
67 # args.a and a are the same
68 some = "value";
69}
70```
71
72## nginx regex location
73```nix
74{
75 locations."~ \.php$".extraConfig = ''
76 # balls
77 '';
78}
79```
80from [nixos wiki](https://nixos.wiki/wiki/Nginx#LEMP_stack)
81
82## adding a package with an overlay to a package set
83
84for package sets with a scope, you will have to do something like
85```nix
86final: prev: {
87 nimPackages = prev.nimPackages.overrideScope (final': prev': {
88 sha1 = final'.callPackage ./sha1.nix {};
89 oauth = final'.callPackage ./oauth.nix {};
90 });
91}
92```
93There's an alternative method that i used to use here:
94
95https://github.com/soopyc/nix-on-koumakan/blob/30e65402d22b000a3b5af6c9e5ea48a2b58a54e0/overlays/nim/oauth/default.nix
96
97however i do not think that's the best way lol
98
99# Common pitfalls
100## importing nixpkgs with an empty attrset
101
102ever had this in your flake.nix
103
104```nix
105{
106 outputs = { nixpkgs, ... }@inputs: let
107 pkgs = import nixpkgs {};
108 lib = nixpkgs.lib;
109 in {
110 # ...
111 };
112}
113```
114
115... and got fucked with this?
116```shell
117error:
118 … while checking flake output 'nixosConfigurations'
119
120 at /nix/store/lz2ra1180qfffmpwg41jpyg1z602qdgx-source/flake.nix:50:5:
121
122 49| in {
123 50| nixosConfigurations = {
124 | ^
125 51| koumakan = (import ./systems/koumakan { inherit pkgs lib inputs; });
126
127 … while checking the NixOS configuration 'nixosConfigurations.koumakan'
128
129 at /nix/store/lz2ra1180qfffmpwg41jpyg1z602qdgx-source/flake.nix:51:7:
130
131 50| nixosConfigurations = {
132 51| koumakan = (import ./systems/koumakan { inherit pkgs lib inputs; });
133 | ^
134 52| };
135
136 (stack trace truncated; use '--show-trace' to show the full trace)
137
138 error: attribute 'currentSystem' missing
139
140 at /nix/store/5c0k827yjq7j24qaq8l2fcnsxp7nv8v1-source/pkgs/top-level/impure.nix:17:43:
141
142 16| # (build, in GNU Autotools parlance) platform.
143 17| localSystem ? { system = args.system or builtins.currentSystem; }
144 | ^
145 18|
146```
147
148just don't!!!11 remove the pkgs definition. (note that this only applies to `pkgs = import nixpkgs {};`)
149
150### explanation
151> you shouldn't ever really import nixpkgs with an empty attrset either
152>
153> that causes it to fall back on guessing your system using `builtins.currentSystem`,
154> which is impure and so not allowed in pure evaluation mode
155— \@getchoo
156## Useful links
157
158Builtin stdlib functions search engine: https://noogle.dev/
159
160
161<!--links-->
162[nixpkgs:lib/modules.nix#122]: https://github.com/NixOS/nixpkgs/blob/6e68daefde56a7a8e6fe7c3ca9ceeb436294bb9f/lib/modules.nix#L122
163[nixpkgs:nixos/lib/eval-config.nix]: https://github.com/NixOS/nixpkgs/blob/5054472759a3b0df8e18cfe4031a5eff92d4cdc3/nixos/lib/eval-config.nix