chore: add nix flake for reproducible dev environment (#695)

- Add Nix flake configuration for reproducible development environment
- Include all required tools: go, terraform, goreleaser, golangci-lint,
gofumpt, pre-commit, etc.
- Update `.envrc` to automatically use the flake when nix is available
- Remove `testacc` from pre-commit hooks (too slow for local commits)

Author: tembleking

.envrc

@@ -1,6 +1,7 @@
-export TF_ACC=true
-export TF_LOG=DEBUG
+has nix && use flake
 dotenv_if_exists .env # You can create a .env file with your env vars for this project. You can also use .secrets if you are using act. See the line below.
 dotenv_if_exists .secrets # Used by [act](https://nektosact.com/) to load secrets into the pipelines
 strict_env
 env_vars_required SYSDIG_SECURE_API_TOKEN SYSDIG_MONITOR_API_TOKEN
+export TF_ACC=true
+export TF_LOG=DEBUG

.pre-commit-config.yaml

@@ -26,9 +26,4 @@ repos:
         pass_filenames: false
         entry: make test
         language: system
-    -   id: testacc
-        name: testacc
-        pass_filenames: false
-        entry: make testacc
-        language: system
 

flake.lock

@@ -0,0 +1,44 @@
+{
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+  outputs =
+    {
+      self,
+      nixpkgs,
+      flake-utils,
+    }:
+    flake-utils.lib.eachDefaultSystem (
+      system:
+      let
+        pkgs = import nixpkgs {
+          inherit system;
+          config.allowUnfree = true;
+        };
+      in
+      {
+        devShells.default =
+          with pkgs;
+          mkShell {
+            packages = [
+              go
+              terraform
+              goreleaser
+              gnupg
+              golangci-lint
+              gofumpt
+              jq
+              gnumake
+              pre-commit
+            ];
+
+            shellHook = ''
+              pre-commit install
+            '';
+          };
+
+        formatter = pkgs.nixfmt-tree;
+      }
+    );
+}