Sops Nix

# create a folder that sops expects to exist when creating keys
mkdir -p ~/.config/sops/age

# create a new key from scratch
nix shell nixpkgs#age -c age-keygen -o ~/.config/sops/age/keys.txt

# create an age key from a private ssh key
nix run nixpkgs#ssh-to-age -- -private-key -i ~/.ssh/private > ~/.config/sops/age/keys.txt
nix-shell -p ssh-to-age --run 'cat ~/.ssh/id_ed25519.pub | ssh-to-age'

# print the public key of ~/.config/sops/age/keys.txt
nix shell nixpkgs#age -c age-keygen -y ~/.config/sops/age/keys.txt

# create a config file at root of the flake and secrets folder
vim .sops.yaml

├── flake.nix
├── .sops.yaml
├── secrets/
│   ├── secrets.yaml

# .sops.yaml
# nix-shell -p ssh-to-age --run 'cat ~/.ssh/id_ed25519.pub | ssh-to-age'
# sops updatekeys secrets/secrets.yaml if you add/remove any keys or if no sops installed:
# nix-shell -p sops --run "sops updatekeys secrets/secrets.yaml"
keys:
  - &users:
    - &megacron agea8a7dsf98a7sydf8as7ydf8as7ydfaos87ydfoa7sdyfoa8s7ydfouahsdfliuhsd      # public key user
  - &hosts:
    - &blackout agea8a7dsf98a7sydf8as7ydf8as7ydfaos87ydfoa7sdyfoa8s7ydfouahsdfliuhsd      # age formatted host key
    - &energon agea8a7dsf98a7sydf8as7ydf8as7ydfaos87ydfoa7sdyfoa8s7ydfouahsdfliuhsd       # age formatted host key
    - &galvatron agea8a7dsf98a7sydf8as7ydf8as7ydfaos87ydfoa7sdyfoa8s7ydfouahsdfliuhsd     # age formatted host key
    - &ratchet agea8a7dsf98a7sydf8as7ydf8as7ydfaos87ydfoa7sdyfoa8s7ydfouahsdfliuhsd       # age formatted host key

creation_rules:
  - path_regex: secrets/secrets.yaml$
    key_groups:
    - age:
      - *megacron
      - *hosts

# create/edit a secrets file at root of the flake
sops secrets.yaml

# if you only have nix installed use nix shell
nix-shell -p sops --run "sops secrets/secrets.yaml"

# This is a comment
example_key: example_value
example_array:
  - example_value1
  - example_value2
example_number: 1234.5678
example_boolean:
  - true
  - false

# hash a password
echo "password" | mkpasswd -s

# configuration.nix
{ config, ... }:
{
  sops.secrets.megacron-password.neededForUsers = true;

  users.users.megacron = {
    isNormalUser = true;
    hashedPasswordFile = config.sops.secrets.megacron-password.path;
  };
}

# secrets.yaml
private_keys:
  megacron: |   # key must be same level of indentation as the pipe
            -----BEGIN PRIVATE KEY-----
            asfdasdfasdfioasdfoiasjdfoasidjfaosijdfasidjf
            -----END PRIVATE KEY-----
megacronPW: passwordwehashed  # mkpasswd -s
smtp-password: asfdasdfasdfioasdfoiasjdfoasidjfaosijdfasidjf
megacron-password: asfdasdfasdfioasdfoiasjdfoasidjfaosijdfasidjf

# add as an input to flake (follows line optional)
sops-nix.url = "github:Mic92/sops-nix";
sops-nix.inputs.nixpkgs.follows = "nixpkgs";

# then also add to nixosConfigurations
specialArgs = { inherit inputs; };  <-This
modules = [ ./configuration.nix ];

# open configuration.nix and add to imports
imports = [
  inputs.sops-nix.nixosModules.sops
];

sops = {
  defaultSopsFile = ./secrets/secrets.yaml;
  defaultSopsFormat = "yaml";
  age.keyFile = "home/user/.config/sops/age/keys.txt";

  # how to place secret values
  secrets.some-key = { };
  secrets."dir/subdir/secret" = { };

  # add another owner to your keys
  owner = "bob"
  owner = config.users.users.bob.name;
};

# this would cat out the value in plain text
$(cat ${config.sops.secrets."dir/subdir/secret".path})

{ inputs, config, ... }:

{
  imports = [
    inputs.sops-nix.nixosModules.sops
  ];

  sops = {
    defaultSopsFile = "secrets.yaml";
    validateSopsFiles = false;

    age = {
      sshKeyPaths = [ "/etc/ssh/ssh_host_ed25519_key" ];  # auto import host ssh keys as age keys
      keyFile = "/var/lib/sops/age/key.txt";  # expected age key to already be on filesystem
      generateKey = true;  # generate a new age key if one does not exist
    };

    # secrets will be output to /run/secrets
    # e.g. /run/secrets/msmtp-password
    # secrets required for user creation are handled in respective ./users/<username>.nix files
    # because they will be output to /run/secrets-for-users and only when the user is assigned to a host.
    secrets = {
      megacronPW = { };
      megacronPW.neededForUsers = true;

      msmtp-host = { };
      msmtp-address = { };
      msmtp-password = { };

      # extract to default pam-u2f authfile location for passwordless sudo. see ../optional/yubikey
      "yubico/u2f_keys" = {
        path = "/home/ta/.config/Yubico/u2f_keys";
      };
    };
  };
}

# configuration.nix
users.mutableUsers = false;     # allow pw to be set during build process
users.users.username = {
  hashedPasswordFile = config.sops.secrets.username.path;
  openssh.authorizedKeys = [
    (builtins.readFile ./secrets/id_blackout.pub)
  ];
};

# afterward run without --refresh
systemctl --user reset-failed