When I build socrates using `sudo nixos-rebuild [...] switch`, my
`nixos-config` (i.e. <briefcase/nixos/socrates/default.nix>) is a simple Nix
anonymous function. Typically readTree populates my pkgs, briefcase, depot
function parameters with <nixpkgs>, <briefcase>, <depot>, but `nixos-rebuild` is
unaware of `readTree`.
For now I'm manually importing these dependencies, and I'm leaving a TODO to
reconsider switching to the `{ pkgs, briefcase, ... }` style when I better
understand NixOS.
At the moment, I don't think nixos-rebuild is reading $NIX_PATH, which
appropriately sets the paths for depot and briefcase. I'm going to explicitly
expose these values in the rebuild script for now.
After I considered the security implications of calling
`systemctl --user cat monzo-token-server`, I realized that monzo-token-server
should be a root service instead of a user service.
This service unit now also explicitly depends on briefcase.monzo_ynab.tokens,
which is a big improvement.
"oneshot", according to `man systemd.service`, "will consider the unit up after
the main process exits". Since I designed token-server to run continuously, it
will not intentionally exit; therefore, systemd awaits its exit, which never
comes. "simple", on the other hand, does what I want.
Here is my first attempt to manage secrets when I deploy onto a NixOS machine.
Background: When I develop, I use direnv, which reads an .envrc file in which I
define my secrets. My secrets are read from `pass` using a pattern like this...
```shell
secret_value="$(pass show path/to/secret)"
```
...Thus far, I've found this pattern convenient. `pass show` invokes GPG, which
asks me for a password to authenticate. This means that when I cd into a
directory with an .envrc file using this pattern, I may be prompted by GPG for a
password. When I'm not, it's because gpg-agent is still caching my
password. This works for development, but I currently do not know how to use
direnv for deployments.
Here is what I'm using until I find a more convenient solution:
- Store the secrets in /etc/secrets on socrates. Ensure that the /etc/secrets
directory and its contents are only readable by root.
- Use systemd's Environment and NixOS's builtins.readFile to read the files in
/etc/secrets when I can `sudo nixos-rebuild`.
Ideally I could call a function like `builtins.readFromPasswordStore` within
configuration.nix. This would allow me to skip the step where I run...
```shell
> ssh socrates
> pass show finance/monzo/client-id | sudo tee /etc/secrets/monzo-client-id
> pass show finance/monzo/client-secret | sudo tee /etc/secrets/monzo-client-secret
> # etc
```
...I don't know how to manage secrets using NixOS, but at least this is one
answer.
TL;DR:
- Move /etc/nixos/configuration.nix -> //nixos/configuration.nix
- Move /etc/nixos/hardware-configuration.nix -> //nixos/harware.nix
- Document installer.nix
- Create rebuild.nix wrapper around `sudo nixos-rebuild switch`
Previously I sketched ideas for the configuration.nix for socrates -- also known
as flattop -- the inexpensive Acer laptop residing in my flat and stored that
configuration.nix file in briefcase. Now, however, I have successfully installed
NixOS onto socrates. By default NixOS saves the configuration.nix and
hardware-configuration.nix files to /etc/nixos/. I'm moving both of these files
into briefcase.
Because the command `nixos-rebuild` looks for the NixOS configuration
file in /etc/nixos, I wrote rebuild.nix, which creates a program to
call `nixos-rebuild` with the new location of my configuration.nix.
The command...
nix-build -A config.system.build.isoImage -I nixos-config=installer.nix nixos
...creates an .iso file in the ./result directory. You can then copy this onto a
USB and use it a custom installer...
cp ./result/iso/*-linux.iso /dev/sda
I needed an installer that used a version of the Linux kernel higher than the
one distributed on NixOS's website: 4.19.? -> 5.4.20+. My Acer laptop needed a
version of the kernel that supported its network controller: Intel 3168NGW.
TODO(wpcarro): Pin the nixpkgs git commit SHA inside of installer.nix.
I'm attempting to configure an old Acer laptop that I bought at a used
electronics store in Shepherd's Bush (~100GBP) as my server. I'd like to install
NixOS on it. The configuration.nix herein defines a starting point for the
configuration for that machine. It isn't currently working.
Troubleshooting and solutions forthcoming...
