Implement Keystone environment deployments

app/Http/Controllers/EnvironmentVariableController.php

@@ -0,0 +1,45 @@
+<?php
+
+namespace App\Http\Controllers;
+
+use App\Enums\EnvironmentVariableSource;
+use App\Http\Requests\StoreEnvironmentVariableRequest;
+use App\Models\Organisation;
+use Illuminate\Http\RedirectResponse;
+use Illuminate\Http\Request;
+use Inertia\Response;
+
+class EnvironmentVariableController extends Controller
+{
+    public function create(Request $request): Response
+    {
+        $organisation = Organisation::findOrFail($request->route('organisation'));
+        $application = $organisation->applications()->findOrFail($request->route('application'));
+        $environment = $application->environments()->findOrFail($request->route('environment'));
+
+        return inertia('environment-variables/Create', [
+            'application' => $application,
+            'environment' => $environment,
+        ]);
+    }
+
+    public function store(StoreEnvironmentVariableRequest $request): RedirectResponse
+    {
+        $organisation = Organisation::findOrFail($request->route('organisation'));
+        $application = $organisation->applications()->findOrFail($request->route('application'));
+        $environment = $application->environments()->findOrFail($request->route('environment'));
+
+        $environment->variables()->updateOrCreate([
+            'key' => $request->string('key')->toString(),
+        ], [
+            'value' => $request->string('value')->toString(),
+            'source' => EnvironmentVariableSource::USER,
+            'service_slice_id' => null,
+            'overridable' => true,
+        ]);
+
+        return redirect()
+            ->route('applications.show', ['organisation' => $organisation->id, 'application' => $application->id])
+            ->with('success', 'Environment variable saved.');
+    }
+}