Re: [Libguestfs] [PATCH] v2v: rhv-upload-plugin: Defer imageio connection

When using vddk input with certain vmware version, qemu-img may spend lot of time getting source image extents. If getting image extents takes more than 60 seconds, imageio server closes the idle connection, and the transfer will fail on the first write with: nbdkit: python[1]: error: /var/tmp/rhvupload.0OKqWA/rhv-upload-plugin.py: pwrite: error: Traceback (most recent call last): File "/var/tmp/rhvupload.0OKqWA/rhv-upload-plugin.py", line 94, in wrapper return func(h, *args) File "/var/tmp/rhvupload.0OKqWA/rhv-upload-plugin.py", line 230, in pwrite r = http.getresponse() File "/usr/lib64/python3.6/http/client.py", line 1361, in getresponse response.begin() File "/usr/lib64/python3.6/http/client.py", line 311, in begin version, status, reason = self._read_status() File "/usr/lib64/python3.6/http/client.py", line 280, in _read_status raise RemoteDisconnected("Remote end closed connection without" http.client.RemoteDisconnected: Remote end closed connection without response Fix the issue by deferring the actual connection used for the transfer until qemu try to write to the server: - The first connection is created in open(). This connection is used to query imageio server options and initialize the handle. - The second connection is created on the first call of the nbd callbacks (pwrite, zero, ...). We store it in the handle and reuse it for the rest of the transfer. Since we set inactivity_timeout to 3600 seconds, oVirt will keep the transfer alive for one hour. If more time is needed to get image extents, we need to increase the inactivity timeout. I did not test this change yet, but I tested the approach using oVirt upload_disk.py example script. Posting early to get feedback on this approach.