fix(proxy): fetch failed (#10346)

* fix(backups): fetch failed

disable compresion between xoa on proxy on xoa side

* fix(xo-proxy): disable compression on the proxy

it was disable with hrp, replaced by #10038 since it was never
sending accept-encoding header

compression can be put back later on a route by route basis after
careful checks ( for example : file restore, backup listing )

@xen-orchestra/proxy/app/mixins/api.mjs

@@ -68,6 +68,15 @@ export default class Api {
       // not be enough for the API.
       ctx.req.setTimeout(0)
 
+      // Compression is disabled for the whole API.
+      //
+      // A compressor buffers its input, so a streamed response would not reach the
+      // client as it is produced. With brotli — which `fetch` negotiates by default
+      // over HTTPS — nothing at all is emitted before its window fills, not even the
+      // response headers, and the client times out waiting for them.
+      //
+      ctx.compress = false
+
       const profile = await app.authentication.findProfile({
         token: ctx.cookies.get('authenticationToken'),
       })

CHANGELOG.unreleased.md

@@ -15,6 +15,8 @@
 
 > Users must be able to say: "I had this issue, happy to know it's fixed"
 
+- [Backups] Fix error `fetch failed` on backup with proxies (PR [#10346](https://github.com/vatesfr/xen-orchestra/pull/10346))
+
 ### Packages to release
 
 > When modifying a package, add it here with its release type.
@@ -31,4 +33,6 @@
 
 <!--packages-start-->
 
+- @xen-orchestra/proxy patch
+- xo-server patch
 <!--packages-end-->

packages/xo-server/src/xo-mixins/proxies.mjs

@@ -474,13 +474,19 @@ export default class Proxy {
     const proxy = await this._getProxy(id)
 
     const url = new URL('https://localhost/api/v1')
-
-    const request = {
-      body: format.request(0, method, params),
-      headers: {
+    const headers = {
       'Content-Type': 'application/json',
       Cookie: cookie.serialize('authenticationToken', proxy.authenticationToken),
-      },
+    }
+    if (assertType !== 'scalar') {
+      // the proxy streams ndjson and binary responses incrementally; a compressor
+      // buffers them (brotli emits nothing until its window fills), so the response
+      // headers are never flushed and `headersTimeout` fires
+      headers['Accept-Encoding'] = 'identity'
+    }
+    const request = {
+      body: format.request(0, method, params),
+      headers,
       method: 'POST',
       dispatcher: this._getAgent(timeout),
     }