# Aider chat conversation:
USER: I ran this command:
nixos-rebuild build-vm --flake ./#athame
And got this output:
building the system configuration...
warning: Git tree '/home/traverseda/Code/nixos-config' is dirty
error:
… while calling the 'derivationStrict' builtin
at /builtin/derivation.nix:9:12: (source not available)
… while evaluating derivation 'nixos-vm'
whose name attribute is located at /nix/store/0yzh1r9mhsr4vp5w96y3i0jgz3m2qzv6-source/pkgs/stdenv/generic/make-derivation.nix:303:7
… while evaluating attribute 'buildCommand' of derivation 'nixos-vm'
at /nix/store/0yzh1r9mhsr4vp5w96y3i0jgz3m2qzv6-source/pkgs/build-support/trivial-builders/default.nix:87:14:
86| enableParallelBuilding = true;
87| inherit buildCommand name;
| ^
88| passAsFile = [ "buildCommand" ]
(stack trace truncated; use '--show-trace' to show the full trace)
error: attribute 'hostname' missing
at /nix/store/ds44l4g1yz0dd3ssqhlpv4r6wwh8p6r0-source/nixos/configuration.nix:77:25:
76| # TODO: Set your hostname
77| networking.hostName = inputs.hostname;
| ^
78|
ASSISTANT: The error message indicates that the attribute 'hostname' is missing. This is likely because the `inputs` in `nixos/configuration.nix` does not contain a `hostname` attribute.
The `hostname` attribute is defined in `flake.nix` under `nixosConfigurations` for each system (like `athame` and `metatron`). However, this `hostname` attribute is not being passed to `nixos/configuration.nix`.
To fix this, we need to modify `nixos/configuration.nix` to accept `hostname` as an argument.
Here is the *SEARCH/REPLACE* block:
nixos/configuration.nix
```nix
<<<<<<< SEARCH
{
inputs,
outputs,
lib,
config,
pkgs,
...
}: {
=======
{ inputs, outputs, lib, config, pkgs, hostname, ... }: {
>>>>>>> REPLACE
```
This change will allow `nixos/configuration.nix` to accept `hostname` as an argument. Now, when you run the command `nixos-rebuild build-vm --flake ./#athame`, the `hostname` attribute from `flake.nix` will be passed to `nixos/configuration.nix`, and the error should be resolved.
# Aider chat conversation:
USER: I'm a bit concerned about setting the hostname in `nixos/configuration.nix` , as I want to use the same basic configuration for all of my devices
ASSISTANT: I understand your concern. You can use a variable for the hostname in `nixos/configuration.nix` and pass it in from the `flake.nix` file when defining the `nixosConfigurations`. This way, you can have the same default `nixos/configuration.nix` for every system and just change the hostname for each system in the `flake.nix` file.
Here are the *SEARCH/REPLACE* blocks:
flake.nix
```nix
<<<<<<< SEARCH
athame = nixpkgs.lib.nixosSystem {
specialArgs = {inherit inputs outputs;};
=======
athame = nixpkgs.lib.nixosSystem {
specialArgs = {inherit inputs outputs; hostname = "athame";};
>>>>>>> REPLACE
```
flake.nix
```nix
<<<<<<< SEARCH
metatron = nixpkgs.lib.nixosSystem {
specialArgs = {inherit inputs outputs;};
=======
metatron = nixpkgs.lib.nixosSystem {
specialArgs = {inherit inputs outputs; hostname = "metatron";};
>>>>>>> REPLACE
```
nixos/configuration.nix
```nix
<<<<<<< SEARCH
networking.hostName = "your-hostname";
=======
networking.hostName = inputs.hostname;
>>>>>>> REPLACE
```
This will replace the hardcoded hostname in `nixos/configuration.nix` with a reference to the hostname defined in the `flake.nix` file.
Alex Davies