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Message #23693
[Bug 1380776] [NEW] Uploading and downloading VHDs via Glance XenAPI plugin doesn't always retry when it should
Public bug reported:
Encountered a situation where one glance node could not talk to registry
which resulted in a high number of upload_vhd errors. The Glance XenAPI
plugin doesn't properly differentiate between server permanent and
globally permanent errors. This is only reasonable behavior in the case
where there is a single glance node. In the case of many glance nodes
retrying a different server is preferable.
Ideally:
Retry until:
1. A non-retryable error is encountered (e.g. 403)
2. Max retries is reached
3. No servers left to retry (i.e. every server was dropped from the retry list due to a permanent error)
If the glance nodes sit behind a load balancer (proxy), this approach
could result in the LB being treated as a single glance endpoint (no
retries for server errors). Retrying on server errors without dropping
servers with server errors from the list could result in unnecessary
retries, especially in the case where there is only a single glance
node.
Additionally, if multiple errors are encountered, only the last error is logged as an instance error. Every error should be recorded.
Examples:
Current:
* The plugin tries to upload using 1 of n glance nodes (n > 1)
* An ephemeral (retryable) error is encountered
* The plugin retries using a different glance node
* An error related to a server fault (e.g. 500) is encountered
* The plugin does not retry
* Instance fault
Expected:
* The plugin tries to upload using 1 of n glance nodes (n > 1)
* An ephemeral (retryable) error is encountered
* Instance fault
* The plugin retries using a different glance node
* An error related to a server fault (e.g. 500) is encountered
* The plugin retries using a different glance node
* Success
** Affects: nova
Importance: Undecided
Assignee: Jesse J. Cook (jesse-j-cook)
Status: In Progress
** Changed in: nova
Status: New => In Progress
** Changed in: nova
Assignee: (unassigned) => Jesse J. Cook (jesse-j-cook)
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https://bugs.launchpad.net/bugs/1380776
Title:
Uploading and downloading VHDs via Glance XenAPI plugin doesn't always
retry when it should
Status in OpenStack Compute (Nova):
In Progress
Bug description:
Encountered a situation where one glance node could not talk to
registry which resulted in a high number of upload_vhd errors. The
Glance XenAPI plugin doesn't properly differentiate between server
permanent and globally permanent errors. This is only reasonable
behavior in the case where there is a single glance node. In the case
of many glance nodes retrying a different server is preferable.
Ideally:
Retry until:
1. A non-retryable error is encountered (e.g. 403)
2. Max retries is reached
3. No servers left to retry (i.e. every server was dropped from the retry list due to a permanent error)
If the glance nodes sit behind a load balancer (proxy), this approach
could result in the LB being treated as a single glance endpoint (no
retries for server errors). Retrying on server errors without dropping
servers with server errors from the list could result in unnecessary
retries, especially in the case where there is only a single glance
node.
Additionally, if multiple errors are encountered, only the last error is logged as an instance error. Every error should be recorded.
Examples:
Current:
* The plugin tries to upload using 1 of n glance nodes (n > 1)
* An ephemeral (retryable) error is encountered
* The plugin retries using a different glance node
* An error related to a server fault (e.g. 500) is encountered
* The plugin does not retry
* Instance fault
Expected:
* The plugin tries to upload using 1 of n glance nodes (n > 1)
* An ephemeral (retryable) error is encountered
* Instance fault
* The plugin retries using a different glance node
* An error related to a server fault (e.g. 500) is encountered
* The plugin retries using a different glance node
* Success
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