backport of commit a35acdb84e2445930598663bb8cbc133e9832b4d (#19264)

Co-authored-by: Phil Renaud <phil.renaud@hashicorp.com>

.changelog/19220.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+ui: fix an issue where starting a stopped job with default-less variables would not retain those variables when done via the job page start button in the web ui
+```

ui/app/components/job-editor.js

@@ -11,6 +11,7 @@ import { task } from 'ember-concurrency';
 import messageFromAdapterError from 'nomad-ui/utils/message-from-adapter-error';
 import localStorageProperty from 'nomad-ui/utils/properties/local-storage';
 import { tracked } from '@glimmer/tracking';
+import jsonToHcl from 'nomad-ui/utils/json-to-hcl';
 
 /**
  * JobEditor component that provides an interface for editing and managing Nomad jobs.
@@ -39,9 +40,7 @@ export default class JobEditor extends Component {
     if (this.args.variables) {
       this.args.job.set(
         '_newDefinitionVariables',
-        this.jsonToHcl(this.args.variables.flags).concat(
-          this.args.variables.literal
-        )
+        jsonToHcl(this.args.variables.flags).concat(this.args.variables.literal)
       );
     }
   }
@@ -258,24 +257,6 @@ export default class JobEditor extends Component {
     }
   }
 
-  /**
-   * Convert a JSON object to an HCL string.
-   *
-   * @param {Object} obj - The JSON object to convert.
-   * @returns {string} The HCL string representation of the JSON object.
-   */
-  jsonToHcl(obj) {
-    const hclLines = [];
-
-    for (const key in obj) {
-      const value = obj[key];
-      const hclValue = typeof value === 'string' ? `"${value}"` : value;
-      hclLines.push(`${key}=${hclValue}\n`);
-    }
-
-    return hclLines.join('\n');
-  }
-
   get data() {
     return {
       cancelable: this.args.cancelable,

ui/app/components/job-page/parts/title.js

@@ -10,6 +10,7 @@ import { inject as service } from '@ember/service';
 import messageFromAdapterError from 'nomad-ui/utils/message-from-adapter-error';
 import { tagName } from '@ember-decorators/component';
 import classic from 'ember-classic-decorator';
+import jsonToHcl from 'nomad-ui/utils/json-to-hcl';
 
 @classic
 @tagName('')
@@ -76,6 +77,16 @@ export default class Title extends Component {
     // In the event that this fails, fall back to the raw definition.
     try {
       const specification = yield job.fetchRawSpecification();
+
+      let _newDefinitionVariables = job.get('_newDefinitionVariables') || '';
+      if (specification.VariableFlags) {
+        _newDefinitionVariables += jsonToHcl(specification.VariableFlags);
+      }
+      if (specification.Variables) {
+        _newDefinitionVariables += specification.Variables;
+      }
+      job.set('_newDefinitionVariables', _newDefinitionVariables);
+
       job.set('_newDefinition', specification.Source);
     } catch {
       const definition = yield job.fetchRawDefinition();

ui/app/utils/json-to-hcl.js

@@ -0,0 +1,24 @@
+/**
+ * Copyright (c) HashiCorp, Inc.
+ * SPDX-License-Identifier: BUSL-1.1
+ */
+
+// @ts-check
+
+/**
+ * Convert a JSON object to an HCL string.
+ *
+ * @param {Object} obj - The JSON object to convert.
+ * @returns {string} The HCL string representation of the JSON object.
+ */
+export default function jsonToHcl(obj) {
+  const hclLines = [];
+
+  for (const key in obj) {
+    const value = obj[key];
+    const hclValue = typeof value === 'string' ? `"${value}"` : value;
+    hclLines.push(`${key}=${hclValue}\n`);
+  }
+
+  return hclLines.join('\n');
+}