feat(xo-server): pass backup network address to proxy

Fixes zammad#4836

CHANGELOG.unreleased.md

@@ -12,6 +12,7 @@
 > Users must be able to say: “I had this issue, happy to know it's fixed”
 
 - [Self service] Change identifiers used for VM templates to avoid them from being removed on XCP-ng upgrade
+- [Proxy] Always connect to XAPI via [backup network if defined](https://xen-orchestra.com/blog/xen-orchestra-5-64/#backupmigrationnetwork)
 
 ### Packages to release
 
@@ -30,6 +31,8 @@
 >
 > In case of conflict, the highest (lowest in previous list) `$version` wins.
 
+- xen-api minor
+- @xen-orchestra/xapi
 - @vates/predicates major
 - @xen-orchestra/mixins minor
 - @xen-orchestra/backups patch

packages/xen-api/src/index.js

@@ -818,22 +818,14 @@ export class Xapi extends EventEmitter {
     }
   }
 
-  async _setHostAddressInUrl(url, host) {
-    const pool = this._pool
-
-    const poolBackupNetwork = pool.other_config['xo:backupNetwork']
+  async _getHostBackupAddress(host) {
     if (host === undefined) {
-      if (poolBackupNetwork === undefined) {
-        const xapiUrl = this._url
-        url.hostname = xapiUrl.hostname
-        url.port = xapiUrl.port
-        return
-      }
-
-      host = await this.getRecord('host', pool.master)
+      host = await this.getRecord('host', this._pool.master)
     }
 
     let { address } = host
+
+    const poolBackupNetwork = this._pool.other_config['xo:backupNetwork']
     if (poolBackupNetwork !== undefined) {
       const hostPifs = new Set(host.PIFs)
       try {
@@ -855,7 +847,26 @@ export class Xapi extends EventEmitter {
       }
     }
 
-    url.hostname = address
+    return address
+  }
+
+  async getHostBackupUrl(host) {
+    return Object.assign(new URL('http://localhost'), {
+      ...this._url,
+      hostname: await this._getHostBackupAddress(host),
+    })
+  }
+
+  async _setHostAddressInUrl(url, host) {
+    const poolBackupNetwork = this._pool.other_config['xo:backupNetwork']
+    if (host === undefined && poolBackupNetwork === undefined) {
+      const xapiUrl = this._url
+      url.hostname = xapiUrl.hostname
+      url.port = xapiUrl.port
+      return
+    }
+
+    url.hostname = await this._getHostBackupAddress(host)
   }
 
   _setUrl(url) {

packages/xo-server/src/xo-mixins/backups-ng/index.mjs

@@ -270,14 +270,17 @@ export default class BackupNg {
               remotes[id] = remote
             }),
             asyncMapSettled([...servers], async id => {
-              const { allowUnauthorized, host, password, username } = await app.getXenServer(id)
+              const { allowUnauthorized, password, username } = await app.getXenServer(id)
+
+              const xapi = app.getAllXapis()[id]
+
               xapis[id] = {
                 allowUnauthorized,
                 credentials: {
                   username,
                   password,
                 },
-                url: host,
+                url: await xapi.getHostBackupUrl(xapi.pool.$master),
               }
             }),
           ])