ui: keep root disk size when the same template is selected again

ui/src/views/compute/DeployVM.vue

@@ -2037,12 +2037,17 @@ export default {
     },
     updateFieldValue (name, value) {
       if (name === 'templateid') {
+        // DiskSizeSelection only re-emits the size when minrootdisksize changes, so keep it for the same template
+        const rootDiskSize = this.form.templateid === value ? this.form.rootdisksize : undefined
         this.imageType = 'templateid'
         this.form.templateid = value
         this.form.isoid = null
         this.form.volumeid = null
         this.form.snapshotid = null
         this.resetFromTemplateConfiguration()
+        if (rootDiskSize) {
+          this.form.rootdisksize = rootDiskSize
+        }
         let template = ''
         for (const entry of Object.values(this.options.templates)) {
           template = entry?.template.find(option => option.id === value) || null

ui/tests/unit/views/compute/DeployVMRootDiskSize.spec.js

@@ -0,0 +1,72 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+import DeployVM from '@/views/compute/DeployVM'
+
+jest.mock('@views/compute/wizard/OwnershipSelection', () => ({}), { virtual: true })
+jest.mock('@views/compute/wizard/DeployButtons', () => ({}), { virtual: true })
+jest.mock('@views/compute/wizard/ZoneBlockRadioGroupSelect', () => ({}), { virtual: true })
+jest.mock('@views/compute/wizard/ComputeOfferingSelection', () => ({}), { virtual: true })
+jest.mock('@views/compute/wizard/ComputeSelection', () => ({}), { virtual: true })
+jest.mock('@views/compute/wizard/DiskOfferingSelection', () => ({}), { virtual: true })
+jest.mock('@views/compute/wizard/DiskSizeSelection', () => ({}), { virtual: true })
+jest.mock('@views/compute/wizard/MultiDiskSelection', () => ({}), { virtual: true })
+jest.mock('@views/compute/wizard/TemplateIsoSelection', () => ({}), { virtual: true })
+jest.mock('@views/compute/wizard/OsBasedImageSelection', () => ({}), { virtual: true })
+jest.mock('@views/compute/wizard/AffinityGroupSelection', () => ({}), { virtual: true })
+jest.mock('@views/compute/wizard/NetworkSelection', () => ({}), { virtual: true })
+jest.mock('@views/compute/wizard/NetworkConfiguration', () => ({}), { virtual: true })
+jest.mock('@views/compute/wizard/SshKeyPairSelection', () => ({}), { virtual: true })
+jest.mock('@views/compute/wizard/UserDataSelection', () => ({}), { virtual: true })
+jest.mock('@views/compute/wizard/SecurityGroupSelection', () => ({}), { virtual: true })
+jest.mock('@views/compute/wizard/DeployInstanceBackupSelection', () => ({}), { virtual: true })
+
+const createContext = (form) => {
+  const template = { id: 'template-1', details: {}, hypervisor: 'KVM', size: 8 * 1024 * 1024 * 1024 }
+  return {
+    form,
+    instanceConfig: form,
+    options: { bootModes: [], templates: { featured: { template: [template] } } },
+    params: { serviceOfferings: { options: {} } },
+    dataPreFill: { minrootdisksize: 8 },
+    deleteFrom: DeployVM.methods.deleteFrom,
+    resetFromTemplateConfiguration: DeployVM.methods.resetFromTemplateConfiguration,
+    handleSearchFilter: jest.fn(),
+    fetchBootModes: jest.fn(),
+    resetTemplateAssociatedResources: jest.fn(),
+    updateTemplateLinkedUserData: jest.fn(),
+    updateTemplateParameters: jest.fn()
+  }
+}
+
+describe('DeployVM root disk size on template selection', () => {
+  it('keeps the root disk size when the same template is selected again', () => {
+    const context = createContext({ templateid: 'template-1', rootdisksize: 8 })
+
+    DeployVM.methods.updateFieldValue.call(context, 'templateid', 'template-1')
+
+    expect(context.form.rootdisksize).toBe(8)
+  })
+
+  it('clears the root disk size when another template is selected', () => {
+    const context = createContext({ templateid: 'template-0', rootdisksize: 20 })
+
+    DeployVM.methods.updateFieldValue.call(context, 'templateid', 'template-1')
+
+    expect(context.form.rootdisksize).toBeUndefined()
+  })
+})