NixOS Configs using Flakes

How to change and install

1. Clone this repo
2. For a new machine
   • add new platform in directory under ./platform/<machine>
   • make appropriate changes from configuration.nix and hadrware-configuration.nix
   • add the machine to flake.nix
3. Run the nixos-rebuild: sudo nixos-rebuild switch --install-bootloader --flake .#<machine>
4. Move ./confs files to their appropriate locations

Update (not upgrade)

1. cd ~/somenix
2. sudo nix flake update
3. sudo nixos-rebuild switch --flake .#machine-name

List generations

1. cd ~/somenix
2. sudo nix-env -p /nix/var/nix/profiles/system --list-generations

Garbage collection

1. cd ~/somenix
2. sudo nix-collect-garbage --delete-older-than 1d
3. sudo nixos-rebuild switch --flake .#machine-name

Add a new package

1. Create a new file in packages directory.
2. Add various contents that your heart pleases. This is necessary because your heart will bleed debugging it.
3. Pray.
4. Add the call in flake.nix.

Debugging

Build locally while developing

1. Use command ix-build -E 'with import <nixpkgs> { }; callPackage ./packages/yourpackage.nix {}' --show-trace
2. Run result/bin/yourpackage if it builds fine

The SHA256 stuff

You may need various SHAs. You will need to try many many things. As an example, look at nrfdfu.nix. It has two SHAs, one for fetchFromGitHub and other for rustPlatform.buildRustPackage.

Pushing all 0s.

> ERROR: cargoSha256 is out of date
>
> Cargo.lock is not the same in /build/nrfdfu-rs-v0.1.3-vendor.tar.gz
>
> To fix the issue:
> 1. Use "0000000000000000000000000000000000000000000000000000" as the cargoSha256 value
> 2. Build the derivation and wait for it to fail with a hash mismatch
> 3. Copy the 'got: sha256:' value back into the cargoSha256 field
>

Changing cargoHash to others

Like using carghoHash to cargoSha256 will give you better logs

SHA from URL fetching

nix-prefetch-url --unpack --type sha256  https://github.com/user/mypackage/archive/vx.y.z.tar.gz

SRI format

You may need to convert the SHA256 into SRI format using this command

nix hash to-sri --type sha256  0784xz1svjfzsvcd0ghyrjqragvrasll674fn96hg660bv0df5gc

Gratitude

• Spacekookie for introducing me and giving me my first NixOS config to copy
• Ana, Hoverbear for showing me the light of Nix Flakes and giving me the setup to copy
• Graham on being in the NixOS community and constantly improving it
• NixOS folks who constantly improve things
• Friends of this land who help me out when I have questions