fix(deployment): filter null and empty environment variables from nixpacks plan

When application->fqdn is null, COOLIFY_FQDN and COOLIFY_URL are set to null.
These null values cause nixpacks to fail parsing the config with
"invalid type: null, expected a string".

Filter out null and empty string values when generating environment variables
for the nixpacks plan JSON. Fixes #6830.

app/Jobs/ApplicationDeploymentJob.php

@@ -2196,7 +2196,7 @@ private function clone_repository()
         $this->create_workdir();
         $this->execute_remote_command(
             [
-                executeInDocker($this->deployment_uuid, "cd {$this->workdir} && git log -1 ".escapeshellarg($this->commit)." --pretty=%B"),
+                executeInDocker($this->deployment_uuid, "cd {$this->workdir} && git log -1 ".escapeshellarg($this->commit).' --pretty=%B'),
                 'hidden' => true,
                 'save' => 'commit_message',
             ]
@@ -2462,7 +2462,9 @@ private function generate_env_variables()
 
         $coolify_envs = $this->generate_coolify_env_variables(forBuildTime: true);
         $coolify_envs->each(function ($value, $key) {
-            $this->env_args->put($key, $value);
+            if (! is_null($value) && $value !== '') {
+                $this->env_args->put($key, $value);
+            }
         });
 
         // For build process, include only environment variables where is_buildtime = true

openapi.json

@@ -3339,6 +3339,15 @@
                         "schema": {
                             "type": "string"
                         }
+                    },
+                    {
+                        "name": "docker_cleanup",
+                        "in": "query",
+                        "description": "Perform docker cleanup (prune networks, volumes, etc.).",
+                        "schema": {
+                            "type": "boolean",
+                            "default": true
+                        }
                     }
                 ],
                 "responses": {
@@ -5864,6 +5873,15 @@
                         "schema": {
                             "type": "string"
                         }
+                    },
+                    {
+                        "name": "docker_cleanup",
+                        "in": "query",
+                        "description": "Perform docker cleanup (prune networks, volumes, etc.).",
+                        "schema": {
+                            "type": "boolean",
+                            "default": true
+                        }
                     }
                 ],
                 "responses": {
@@ -10561,6 +10579,15 @@
                         "schema": {
                             "type": "string"
                         }
+                    },
+                    {
+                        "name": "docker_cleanup",
+                        "in": "query",
+                        "description": "Perform docker cleanup (prune networks, volumes, etc.).",
+                        "schema": {
+                            "type": "boolean",
+                            "default": true
+                        }
                     }
                 ],
                 "responses": {

openapi.yaml

@@ -2111,6 +2111,13 @@ paths:
           required: true
           schema:
             type: string
+        -
+          name: docker_cleanup
+          in: query
+          description: 'Perform docker cleanup (prune networks, volumes, etc.).'
+          schema:
+            type: boolean
+            default: true
       responses:
         '200':
           description: 'Stop application.'
@@ -3806,6 +3813,13 @@ paths:
           required: true
           schema:
             type: string
+        -
+          name: docker_cleanup
+          in: query
+          description: 'Perform docker cleanup (prune networks, volumes, etc.).'
+          schema:
+            type: boolean
+            default: true
       responses:
         '200':
           description: 'Stop database.'
@@ -6645,6 +6659,13 @@ paths:
           required: true
           schema:
             type: string
+        -
+          name: docker_cleanup
+          in: query
+          description: 'Perform docker cleanup (prune networks, volumes, etc.).'
+          schema:
+            type: boolean
+            default: true
       responses:
         '200':
           description: 'Stop service.'

tests/Unit/ApplicationDeploymentNixpacksNullEnvTest.php

@@ -236,6 +236,48 @@
     expect($envArgs)->toBe('');
 });
 
+it('filters out null coolify env variables from env_args used in nixpacks plan JSON', function () {
+    // This test verifies the fix for GitHub issue #6830:
+    // When application->fqdn is null, COOLIFY_FQDN/COOLIFY_URL get set to null
+    // in generate_coolify_env_variables(). The generate_env_variables() method
+    // merges these into env_args which become the nixpacks plan JSON "variables".
+    // Nixpacks requires all variable values to be strings, so null causes:
+    // "Error: Failed to parse Nixpacks config file - invalid type: null, expected a string"
+
+    // Simulate the coolify env collection with null values (as produced when fqdn is null)
+    $coolify_envs = collect([
+        'COOLIFY_URL' => null,
+        'COOLIFY_FQDN' => null,
+        'COOLIFY_BRANCH' => 'main',
+        'COOLIFY_RESOURCE_UUID' => 'abc123',
+        'COOLIFY_CONTAINER_NAME' => '',
+    ]);
+
+    // Apply the same filtering logic used in generate_env_variables()
+    $env_args = collect([]);
+    $coolify_envs->each(function ($value, $key) use ($env_args) {
+        if (! is_null($value) && $value !== '') {
+            $env_args->put($key, $value);
+        }
+    });
+
+    // Null values must NOT be present — they cause nixpacks JSON parse errors
+    expect($env_args->has('COOLIFY_URL'))->toBeFalse();
+    expect($env_args->has('COOLIFY_FQDN'))->toBeFalse();
+    expect($env_args->has('COOLIFY_CONTAINER_NAME'))->toBeFalse();
+
+    // Non-null values must be preserved
+    expect($env_args->get('COOLIFY_BRANCH'))->toBe('main');
+    expect($env_args->get('COOLIFY_RESOURCE_UUID'))->toBe('abc123');
+
+    // The resulting array must be safe for json_encode into nixpacks config
+    $json = json_encode(['variables' => $env_args->toArray()], JSON_PRETTY_PRINT);
+    $parsed = json_decode($json, true);
+    foreach ($parsed['variables'] as $value) {
+        expect($value)->toBeString();
+    }
+});
+
 it('preserves environment variables with zero values', function () {
     // Mock application with nixpacks build pack
     $mockApplication = Mockery::mock(Application::class);