feat(xo-server): implement warm migration backend

packages/xo-server/src/api/vm.mjs

@@ -596,6 +596,22 @@ migrate.resolve = {
   migrationNetwork: ['migrationNetwork', 'network', 'administrate'],
 }
 
+export async function warmMigration({ vm, sr, startVm, deleteSource }) {
+  await this.warmMigrateVm(vm, sr, startVm, deleteSource)
+}
+warmMigration.permission = 'admin'
+
+warmMigration.params = {
+  vm: {
+    type: 'string',
+  },
+  sr: {
+    type: 'string',
+  },
+  startDestinationVm: { type: 'boolean' },
+  deleteSourceVm: { type: 'boolean' },
+}
+
 // -------------------------------------------------------------------
 
 export const set = defer(async function ($defer, params) {

packages/xo-server/src/xo-mixins/migrate-vm.mjs

@@ -0,0 +1,109 @@
+import { Backup } from '@xen-orchestra/backups/Backup.js'
+import { uuid } from 'uuid'
+
+export default class MigrateVm {
+  constructor(app) {
+    this._app = app
+  }
+
+  // Backup should be reinstentiated each time
+  #createWarmBackup(sourceVmId, srId, jobId) {
+    const app = this._app
+    const config = {
+      snapshotNameLabelTpl: '[XO warm migration {job.name}] {vm.name_label}',
+    }
+    const job = {
+      type: 'backup',
+      id: jobId,
+      mode: 'delta',
+      vms: { id: sourceVmId },
+      name: `Warm migration`,
+      srs: { id: srId },
+      settings: {
+        '': {
+          // mandatory for delta replication writer
+          copyRetention: 1,
+        },
+      },
+    }
+    const schedule = { id: 'one-time' }
+
+    // for now we only support this from the main OA, no proxy
+    return new Backup({
+      config,
+      job,
+      schedule,
+      getAdapter: async remoteId => app.getBackupsRemoteAdapter(await app.getRemoteWithCredentials(remoteId)),
+
+      // `@xen-orchestra/backups/Backup` expect that `getConnectedRecord` returns a promise
+      getConnectedRecord: async (xapiType, uuid) => app.getXapiObject(uuid),
+    })
+  }
+
+  async warmMigrateVm(sourceVmId, srId, startDestVm = true, deleteSource = false) {
+    // we'll use a one time use continuous replication job with the VM to migrate
+    const jobId = uuid.v4()
+    const app = this._app
+    const sourceVm = app.getXapiObject(sourceVmId)
+    let backup = this.#createWarmBackup(sourceVmId, srId, jobId)
+    await backup.run()
+    const xapi = sourceVm.$xapi
+    const ref = sourceVm.$ref
+
+    // stop the source VM before
+    try {
+      await xapi.callAsync('VM.clean_shutdown', ref)
+    } catch (error) {
+      await xapi.callAsync('VM.hard_shutdown', ref)
+    }
+    // make it so it can't be restarted by error
+    const message =
+      'This VM has been migrated somewhere else and might not be up to date, check twice before starting it.'
+    await sourceVm.update_blocked_operations({
+      start: message,
+      start_on: message,
+    })
+
+    // run the transfer again to transfer the changed parts
+    // since the source is stopped, there won't be any new change after
+    backup = this.#createWarmBackup(sourceVmId, srId)
+    await backup.run()
+    // find the destination Vm
+    const targets = Object.keys(
+      app.getObjects({
+        filter: obj => {
+          return (
+            'other' in obj &&
+            obj.other['xo:backup:job'] === jobId &&
+            obj.other['xo:backup:sr'] === srId &&
+            obj.other['xo:backup:vm'] === sourceVm.uuid &&
+            'start' in obj.blockedOperations
+          )
+        },
+      })
+    )
+    if (targets.length === 0) {
+      throw new Error(`Vm target of warm migration not found for ${sourceVmId} on SR ${srId} `)
+    }
+    if (targets.length > 1) {
+      throw new Error(`Multiple target of warm migration found for ${sourceVmId} on SR ${srId} `)
+    }
+    const targetVm = app.getXapiObject(targets[0])
+
+    // new vm is ready to start
+    // delta replication writer as set this as blocked
+    await targetVm.update_blocked_operations({ start: null, start_on: null })
+
+    if (startDestVm) {
+      // boot it
+      await targetVm.$xapi.startVm(targetVm.$ref)
+      // wait for really started
+      // delete source
+      if (deleteSource) {
+        sourceVm.$xapi.VM_destroy(sourceVm.$ref)
+      } else {
+        // @todo should we delete the snapshot if we keep the source vm ?
+      }
+    }
+  }
+}