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.

2 files changed, 62 insertions, 1 deletions

diff --git a/flake/overlays.nix b/flake/overlays.nix
index 1eecfcf..2f9100d 100644
--- a/flake/overlays.nix
+++ b/flake/overlays.nix
@@ -1,4 +1,9 @@
-{ inputs, self, ... }:
+{
+  inputs,
+  self,
+  config,
+  ...
+}:
 {
 
   flake.overlays.default = _final: prev: {
@@ -8,6 +13,17 @@
 
   perSystem =
     { system, ... }:
+    let
+      mkTerraformCfg =
+        modules:
+        inputs.terranix.lib.terranixConfiguration {
+          inherit system;
+          extraArgs = {
+            inherit (config.flake) nixosConfigurations;
+          };
+          inherit modules;
+        };
+    in
     {
       _module.args.pkgs = import inputs.nixpkgs {
         inherit system;
@@ -18,6 +34,11 @@
           inputs.nur.overlays.default
           inputs.my-go-tools.overlays.default
           self.overlays.default
+          (_self: _super: {
+            adminTerraformCfg = mkTerraformCfg [
+              "${self}/terraform/admin"
+            ];
+          })
         ];
       };
     };
diff --git a/flake/terraform.nix b/flake/terraform.nix
new file mode 100644
index 0000000..23cc6d3
--- /dev/null
+++ b/flake/terraform.nix
@@ -0,0 +1,40 @@
+{ lib, ... }:
+{
+  perSystem =
+    { pkgs, ... }:
+    let
+      mkTfWrapper =
+        {
+          tfPlugins,
+          cfg,
+        }:
+        let
+          pkg = pkgs.opentofu.withPlugins tfPlugins;
+        in
+        {
+          type = "app";
+          program = toString (
+            pkgs.writers.writeBash "tf" ''
+              set -xeuo pipefail
+              ln -snf ${cfg} config.tf.json
+              exec ${lib.getExe pkg} "$@"
+            ''
+          );
+        };
+    in
+    {
+      apps = {
+        tf = mkTfWrapper {
+          cfg = pkgs.adminTerraformCfg;
+          tfPlugins = p: [
+            p.cloudflare
+            p.digitalocean
+            p.external
+            p.google
+            p.null
+            p.random
+          ];
+        };
+      };
+    };
+}