feat(xo-server/vm.snapshot): add saveMemory param (#3807)

Related to #3795

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

@@ -747,12 +747,18 @@ export { convertToTemplate as convert }
 // TODO: implement resource sets
 export const snapshot = defer(async function(
   $defer,
-  { vm, name = `${vm.name_label}_${new Date().toISOString()}` }
+  {
+    vm,
+    name = `${vm.name_label}_${new Date().toISOString()}`,
+    saveMemory = false,
+  }
 ) {
   await checkPermissionOnSrs.call(this, vm)
 
   const xapi = this.getXapi(vm)
-  const { $id: snapshotId } = await xapi.snapshotVm(vm._xapiRef, name)
+  const { $id: snapshotId } = await (saveMemory
+    ? xapi.checkpointVm(vm._xapiRef, name)
+    : xapi.snapshotVm(vm._xapiRef, name))
   $defer.onFailure(() => xapi.deleteVm(snapshotId))
 
   const { user } = this
@@ -765,6 +771,7 @@ export const snapshot = defer(async function(
 snapshot.params = {
   id: { type: 'string' },
   name: { type: 'string', optional: true },
+  saveMemory: { type: 'boolean', optional: true },
 }
 
 snapshot.resolve = {

packages/xo-server/src/xapi/mixins/vm.js

@@ -12,6 +12,16 @@ const XEN_VGA_VALUES = ['std', 'cirrus']
 const XEN_VIDEORAM_VALUES = [1, 2, 4, 8, 16]
 
 export default {
+  // https://xapi-project.github.io/xen-api/classes/vm.html#checkpoint
+  checkpointVm(vmId, nameLabel) {
+    const vm = this.getObject(vmId)
+    return this.asyncCall(
+      'VM.checkpoint',
+      vm.$ref,
+      nameLabel != null ? nameLabel : vm.name_label
+    )
+  },
+
   // TODO: clean up on error.
   @deferrable
   async createVm(