From c7f3acde9719e1bdc109bcf00477e6c344d9ee6d Mon Sep 17 00:00:00 2001
From: Ryan Lahfa <ryan@dgnum.eu>
Date: Thu, 10 Oct 2024 12:27:40 +0200
Subject: [PATCH] feat(infra): introduce Terranix

This requires the support for monorepo-terraform-state.s3.dgnum.eu being
available.

`.credentials/` is age-encrypted using only my key for now until we
figure out the right mechanism.

Signed-off-by: Ryan Lahfa <ryan@dgnum.eu>
---
 .credentials/admin-environment.age | 27 ++++++++++++++++++++++
 .credentials/secrets.nix           |  6 +++++
 .gitignore                         |  3 +++
 default.nix                        | 36 ++++++++++++++++++++++++++++++
 npins/sources.json                 | 15 +++++++++++++
 terranix/common.nix                |  7 ++++++
 terranix/default.nix               |  6 +++++
 terranix/state.nix                 | 21 +++++++++++++++++
 8 files changed, 121 insertions(+)
 create mode 100644 .credentials/admin-environment.age
 create mode 100644 .credentials/secrets.nix
 create mode 100644 terranix/common.nix
 create mode 100644 terranix/default.nix
 create mode 100644 terranix/state.nix

diff --git a/.credentials/admin-environment.age b/.credentials/admin-environment.age
new file mode 100644
index 0000000..e44aab3
--- /dev/null
+++ b/.credentials/admin-environment.age
@@ -0,0 +1,27 @@
+age-encryption.org/v1
+-> ssh-ed25519 jIXfPA sIWcGSvcykz9kOFJYILgAm5Xq2PBInCzJP4T2pJKcCE
+/lLwSyz7O2GcrL/m8tLswJxqUHWjMmixnZgaMIbcJlU
+-> ssh-ed25519 QlRB9Q tKNkVMqaxZjjxTTYUiAUMYb+br7bNNpeBU0sacEFchw
+NHBW4eOGqqstzN5flNPPYCSq1gZSXgqWceXuxFvKMFE
+-> ssh-ed25519 r+nK/Q ULxI2nmWCE3/k8zlD40HrfIRXHGDSIJn0WWTBSUfqAU
+27Yp/f6Kq/xxhN2TBfsm+IcowXPA7258mqwOHCWwtNo
+-> ssh-rsa krWCLQ
+cLJmGyyl8JnQhnhqUYLy5nGy83aGB1CeuOSOzuxpUHutnwprbTCQbQDDmMHepzkE
+gO+vqX95E3Y1XH916kV6+0IfgrbUdN3HdQylquHAwrW47en/Nmcnzqmn2eLZv6AJ
+o+HvxlVIj6TnQehuidVPZN1uppgKnmwvlcle9MmaRwCGlC/Ysvpa1yn88uC26wv8
+7b8ONBen25iJaQ79w7f5J9bkoCHQ3hhWQfv1ZrSOfyqwj4L4AimaIRnFRmPLhxma
+wjOBOPA4+ibBhxy0eexKRM5pWuQ6+iY/j6bJyQoEr+TqZADORRAmP7FhC3Uync7f
+TWPZz5kZYsuk4TI4Fv81aw
+-> ssh-ed25519 /vwQcQ 0XpYJjvhUbOdLJ0aQVckn3nx6FTKp+Gf4i3670XnyWQ
+PByb00P+4rE+hwehIgAj35YPdaTebvoljfhYHZQEMcY
+-> ssh-ed25519 0R97PA 9xIPfaZO82LKBHivlhuwXwcV/ZkJzKyQgSlRrlxx/WM
+abN/QW+CJsLvmTPNGoVygcKTHUzAmzedYkgWMl6IXWA
+-> ssh-ed25519 JGx7Ng tI6cHcYUlSikWQ38svssfxv3rvDuFZohsDO/0LFhLxM
+6pkcjuBXxEY+38JLAGKyM5i9cdp7sbgaK1c+SR4Pgsg
+-> ssh-ed25519 5SY7Kg oilxE3BBzEiS3Ufy8CIJpvZZfOXIXGFZpFbZwmGQW3Q
+mn7ILDAvu0P3CfBtsXdbMcA3SO1tCmBI2IJtU74hHYc
+-> ssh-ed25519 p/Mg4Q ZwblCBWNf3JQJAfXyW3v3VPtIqQ/noZ2UotS5Fi6Tiw
++oVJePhLAFnqzJ+reRgssQCH327L3PKe8MZnnbskxvM
+--- VLhXJtb3lZcy11wq5jj8gvY+7Ur+aLqZyQRaaEVfFlA
+���%g&J@�bY�
+�߯�ې�v��_cz5V����'��H�����A��،o��
]~S�����!��]�@ gX@G��Y�����.����!����,9����4l\6Xb�:��3�
�@;�9-�<Y�N[���y=������T��e�9d����u(Y:�	
\ No newline at end of file
diff --git a/.credentials/secrets.nix b/.credentials/secrets.nix
new file mode 100644
index 0000000..c899d92
--- /dev/null
+++ b/.credentials/secrets.nix
@@ -0,0 +1,6 @@
+let
+  keys = import ../keys;
+in
+{
+  "admin-environment.age".publicKeys = keys.rootKeys;
+}
diff --git a/.gitignore b/.gitignore
index d50eeb8..51613c9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,3 +9,6 @@ result-*
 *.qcow2
 .gcroots
 .pre-commit-config.yaml
+
+# Ignore Terraform configuration file
+config.tf.json
diff --git a/default.nix b/default.nix
index 414feb8..cb1ec95 100644
--- a/default.nix
+++ b/default.nix
@@ -67,9 +67,18 @@ let
       commitizen.enable = true;
     };
   };
+
+  terranixConfig = import "${sources.terranix}/core" {
+    inherit pkgs;
+    strip_nulls = true;
+    terranix_config.imports = [ ./terranix ];
+  };
+  terranixConfigFile = (pkgs.formats.json { }).generate "config.tf.json" terranixConfig.config;
 in
 
 {
+  inherit terranixConfigFile terranixConfig;
+
   nodes = builtins.mapAttrs (
     host: { site, ... }: "${host}.${site}.infra.dgnum.eu"
   ) (import ./meta/nodes.nix);
@@ -83,11 +92,36 @@ in
       name = "dgnum-infra";
 
       packages = [
+        (pkgs.writeShellScriptBin "tf" ''
+          set -eo pipefail
+          ln -snf ${terranixConfigFile} config.tf.json
+          exec ${pkgs.lib.getExe pkgs.opentofu} "$@"
+        '')
+        (pkgs.writeShellScriptBin "decryptAndSourceEnvironment" ''
+          set -eo pipefail
+
+          # TODO: don't hardcode me.
+          SECRET_FILE=".credentials/admin-environment.age"
+          IDENTITIES=()
+          for identity in [ "$HOME/.ssh/id_ed25519" "$HOME/.ssh/id_rsa" ]; do
+            test -r "$identity" || continue
+            IDENTITIES+=(-i)
+            IDENTITIES+=("$identity")
+          done
+
+          test "''${#IDENTITIES[@]}" -eq 0 && echo "[agenix-shell] WARNING: no readable identities found!"
+
+          test -f "$SECRET_FILE" || echo "[agenix-shell] WARNING: encrypted environment file $SECRET_FILE not found!"
+          export eval $(${pkgs.lib.getExe pkgs.rage} --decrypt "''${IDENTITIES[@]}" -o - $SECRET_FILE)
+
+          echo "[agenix-shell] Repository-wide secrets loaded in the environment."
+        '')
         (pkgs.nixos-generators.overrideAttrs (_: {
           version = "1.8.0-unstable";
           src = builtins.storePath sources.nixos-generators;
         }))
         pkgs.npins
+        pkgs.rage
 
         (pkgs.callPackage ./lib/colmena { inherit (nix-pkgs) colmena; })
         (pkgs.callPackage "${sources.agenix}/pkgs/agenix.nix" { })
@@ -97,6 +131,8 @@ in
 
       shellHook = ''
         ${git-checks.shellHook}
+        # If we want to export these environments, we need to source it, not call it.
+        source $(which decryptAndSourceEnvironment)
       '';
 
       preferLocalBuild = true;
diff --git a/npins/sources.json b/npins/sources.json
index fa089ef..ee03e5b 100644
--- a/npins/sources.json
+++ b/npins/sources.json
@@ -300,6 +300,21 @@
       "url": null,
       "hash": "11vvfxw2sznc155x0xlgl00g6n9sr90xa0b1hr14vchg7gkz46r5"
     },
+    "terranix": {
+      "type": "GitRelease",
+      "repository": {
+        "type": "GitHub",
+        "owner": "terranix",
+        "repo": "terranix"
+      },
+      "pre_releases": false,
+      "version_upper_bound": null,
+      "release_prefix": null,
+      "version": "2.7.0",
+      "revision": "00710f39f38a0a654a2c4fd96cbb988b4f4cedfa",
+      "url": "https://api.github.com/repos/terranix/terranix/tarball/2.7.0",
+      "hash": "1wsyhsdsjw6xlhpkhaqvia3x0na3nx2vamcb2rbcbdmb7ra1y9f6"
+    },
     "wp4nix": {
       "type": "Git",
       "repository": {
diff --git a/terranix/common.nix b/terranix/common.nix
new file mode 100644
index 0000000..0e8b0be
--- /dev/null
+++ b/terranix/common.nix
@@ -0,0 +1,7 @@
+{
+  # Until we get some kind of KMS operational, store secrets in the state file.
+  terraform.required_providers.secret = {
+    version = "~> 1.2.1";
+    source = "numtide/secret";
+  };
+}
diff --git a/terranix/default.nix b/terranix/default.nix
new file mode 100644
index 0000000..b6ff81e
--- /dev/null
+++ b/terranix/default.nix
@@ -0,0 +1,6 @@
+{
+  imports = [
+    ./common.nix
+    ./state.nix
+  ];
+}
diff --git a/terranix/state.nix b/terranix/state.nix
new file mode 100644
index 0000000..ef2f7d5
--- /dev/null
+++ b/terranix/state.nix
@@ -0,0 +1,21 @@
+{
+  # We use terraform.backend.s3 directly instead of the type-checked Terranix
+  # backend.s3 options. The latter does not support setting arbitrary s3
+  # endpoints.
+  #
+  # Note: currently requires the user to provide AWS_ACCESS_KEY_ID as well as
+  # AWS_SECRET_ACCESS_KEY in their environment variables.
+
+  terraform.backend.s3 = {
+    endpoints.s3 = "s3.dgnum.eu";
+    region = "garage";
+    bucket = "monorepo-terraform-state";
+    key = "state";
+
+    # It's just a dumb Garage server, don't try to be smart.
+    skip_credentials_validation = true;
+    skip_region_validation = true;
+    skip_requesting_account_id = true;
+    skip_metadata_api_check = true;
+  };
+}