manage terraform configuration with terranix

All the terraform configuration is managed within one state instead of
having multiple state for each components. This might not be the best
practice but it simplifies things for me.

Now, all I need to do is to run `nix run .#tf -- plan` and I can see
what will be changed for all the resources that I care about.

1 files changed, 89 insertions, 0 deletions

diff --git a/terraform/admin/droplet-proxy.nix b/terraform/admin/droplet-proxy.nix
new file mode 100644
index 0000000..51ad138
--- /dev/null
+++ b/terraform/admin/droplet-proxy.nix
@@ -0,0 +1,89 @@
+{ lib, pkgs, ... }:
+let
+  serverSize = "s-2vcpu-2gb";
+
+  extraFilesScript = pkgs.writeShellScript "extra-files-script" ''
+    #!/usr/bin/env bash
+    set -euo pipefail
+
+    mkdir -p etc/ssh/
+
+    if [ -n "''${DO_SSH_HOSTKEY:-}" ]; then
+      echo "Setting up SSH host key from environment"
+      echo "$DO_SSH_HOSTKEY" | base64 -d > etc/ssh/ssh_host_ed25519_key
+      chmod 0600 etc/ssh/ssh_host_ed25519_key
+    else
+      echo "Warning: DO_SSH_HOSTKEY environment variable not set"
+    fi
+  '';
+
+in
+{
+  provider.digitalocean = {
+    # Token will be read from DIGITALOCEAN_TOKEN environment variable
+  };
+
+  resource = {
+    # Random string for unique naming
+    random_string.host = {
+      length = 6;
+      special = false;
+      upper = false;
+    };
+
+    digitalocean_ssh_key.default = {
+      name = "nixos-anywhere-\${random_string.host.result}";
+      public_key = lib.tfRef "var.digitalocean_public_key";
+    };
+
+    digitalocean_droplet.nixos = {
+      name = "nixos-\${random_string.host.result}";
+      image = "ubuntu-24-04-x64"; # Bootstrap image
+      size = serverSize;
+      region = lib.tfRef "var.digitalocean_region";
+      ssh_keys = [ "\${digitalocean_ssh_key.default.id}" ];
+      tags = [
+        "nixos"
+        "infrastructure"
+      ];
+    };
+  };
+
+  module = {
+    nixos-system-build = {
+      source = "github.com/nix-community/nixos-anywhere//terraform/nix-build";
+      attribute = ".#nixosConfigurations.do-rproxy.config.system.build.toplevel";
+    };
+
+    nixos-disko = {
+      source = "github.com/nix-community/nixos-anywhere//terraform/nix-build";
+      attribute = ".#nixosConfigurations.do-rproxy.config.system.build.diskoScript";
+    };
+
+    nixos-install = {
+      source = "github.com/nix-community/nixos-anywhere//terraform/install";
+      nixos_system = "\${module.nixos-system-build.result.out}";
+      nixos_partitioner = "\${module.nixos-disko.result.out}";
+      target_host = "\${digitalocean_droplet.nixos.ipv4_address}";
+      build_on_remote = true;
+      extra_files_script = toString extraFilesScript;
+    };
+  };
+
+  output = {
+    server_ip = {
+      description = "IP address of the NixOS server";
+      value = "\${digitalocean_droplet.nixos.ipv4_address}";
+    };
+
+    ssh_command = {
+      description = "SSH command to connect to the server";
+      value = "ssh root@\${digitalocean_droplet.nixos.ipv4_address}";
+    };
+
+    server_name = {
+      description = "Name of the created server";
+      value = "\${digitalocean_droplet.nixos.name}";
+    };
+  };
+}