[PATCH proxmox v2 0/3] fix #6858: implement retry logic for transient API errors

[Christian Ebner <c.ebner@proxmox.com>]

These patches implement the best practice [0] on handling S3 API
response status codes 500, 503 by retrying the requests after an
exponential backoff time. Do the same for status code 504, as this
is returned by some storage providers if overwhelmed [1].

The first 2 patches contain a small fix to avoid additional response
latency in case of request timeout being reached and reorganize the
code for better logical flow. The final patch then adds the
additional response status code checks for retires.

Link to the issue in bugzilla:
https://bugzilla.proxmox.com/show_bug.cgi?id=6858

[0] https://docs.aws.amazon.com/AmazonS3/latest/API/ErrorBestPractices.html
[1] https://forum.proxmox.com/threads/180956/

Changes since version 1 (thanks @Fabian for review):
- return the last error if retries are exhausted
- consider also 504 gateway timeout as retryable

Christian Ebner (3):
  s3-client: early return when request timeout deadline reached
  s3-client: move exponential backoff to after the response state check
  fix #6858: s3-client: retry request on 500, 503 and 504 status codes

 proxmox-s3-client/src/client.rs | 38 ++++++++++++++++-----------------
 1 file changed, 19 insertions(+), 19 deletions(-)

-- 
2.47.3