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Downloading a blob fails for v1.3.1+ if blob is written during download

See original GitHub issue

Note: I understand that this breaking change was done on purpose in commit 8f68597815022e20df5df5402508a2569d8e6bfe. Is there a better way to download a blob that may be written?

Which service(blob, file, queue) does this issue concern?

get_blob_to_path()

Which version of the SDK was used? Please provide the output of `pip freeze`.

azure-storage-blob-1.3.0 works azure-storage-blob-1.3.1 doesn’t work

What problem was encountered?

download fails:

Client-Request-ID=877e7040-7e47-11e9-b109-a08cfde1f962 Retry policy did not allow for a retry: Server-Timestamp=Fri, 24 May 2019 17:15:29 GMT, Server-Request-ID=7b05956d-801e-0008-4b54-12e202000000, HTTP status code=412, Exception=The condition specified using HTTP conditional header(s) is not met. ErrorCode: ConditionNotMet<?xml version="1.0" encoding="utf-8"?><Error><Code>ConditionNotMet</Code><Message>The condition specified using HTTP conditional header(s) is not met.RequestId:7b05956d-801e-0008-4b54-12e202000000Time:2019-05-24T17:15:29.2184347Z</Message></Error>.
Error: The condition specified using HTTP conditional header(s) is not met. ErrorCode: ConditionNotMet
<?xml version="1.0" encoding="utf-8"?><Error><Code>ConditionNotMet</Code><Message>The condition specified using HTTP conditional header(s) is not met.
RequestId:7b05956d-801e-0008-4b54-12e202000000

Have you found a mitigation/solution?

I downgraded to 1.3.0

Issue Analytics

State:
Created 4 years ago
Comments:5 (5 by maintainers)

Top GitHub Comments

1reaction

marco-rossi29commented, Jun 11, 2019

Perfect, that’s a great tip and it will probably solve my issue. Thank you very much for your help!

0reactions

zezha-msftcommented, Jun 9, 2019

Hi @marco-rossi29, thanks for the clarification!

I assume your blob is being manipulated in an append-only pattern, right? E.g. the extra 10MB of data was added at the end of the blob.

To be clear, the SDK is locking onto the blob’s etag to protect the integrity of the downloaded data. In most use cases, there’s no guarantee that the data is being modified in a way that still allows the downloaded data to be “good”, but if you are only appending blocks at the end of the blob, then you could work around the protection by specifying if_match=*.