Azure SAS signatures ending in "=" don't work

[damiondoesthings]

Environment

Delta-rs version: 0.6.4

Binding: Python

Environment:

• Cloud provider: Azure
• OS: MacOs
• Other:

---

Bug

What happened: SAS tokens with signatures ending in "=" passed via storage_options get truncated and won't work.

What you expected to happen: SAS token authenticates all requests to Azure

How to reproduce it:

DeltaTable(
    "abfs://<container_name>",
    storage_options={
        "AZURE_STORAGE_ACCOUNT_NAME": "<account_name>",
        "sas_key": '?sv=2019-07-07&sr=c&sig=ain2DZplwGRn0RHuxrhJSwXl2bkCe0gyVMMJKTMAtFk=&st=2022-12-01T00:00:00Z&se=2022-12-02T00:00:00Z&sp=rl',
    },
)

Results in

PyDeltaTableError: Failed to load checkpoint: Failed to read checkpoint content: Generic MicrosoftAzure error: Error performing get request _delta_log/_last_checkpoint: response error "<?xml version="1.0" encoding="utf-8"?><Error><Code>AuthenticationFailed</Code><Message>Server failed to authenticate the request. Make sure the value of Authorization header is formed correctly including the signature.
Time:2022-12-08T14:26:32.3390349Z</Message><AuthenticationErrorDetail>Signature fields not well formed.</AuthenticationErrorDetail></Error>", after 0 retries: HTTP status client error (403 Forbidden) for url (https://<account_name>.blob.core.windows.net/<container_name>/_delta_log/_last_checkpoint?sv=2019-07-07&sr=c&sig=ain2DZplwGRn0RHuxrhJSwXl2bkCe0gyVMMJKTMAtFk&st=2022-12-01T00:00:00Z&se=2022-12-02T00:00:00Z&sp=rl)

Note that the signature got truncated:
original sig: sig=ain2DZplwGRn0RHuxrhJSwXl2bkCe0gyVMMJKTMAtFk=
request url: sig=ain2DZplwGRn0RHuxrhJSwXl2bkCe0gyVMMJKTMAtFk

More details:
This might originate from the split function here:

delta-rs/rust/src/builder/azure.rs

Line 222 in 16bf4cc

fn split_sas(sas: &str) -> Result<Vec<(String, String)>, BuilderError> {

[roeap]

thanks @damiondoesthings for reporting, and you already identified the root cause :). Good news is, there is an easy fix, we just have to replace the split a few lines below with split_once - any chance you are interested in opening a PR? If not I can probably get to it this weekend.

[damiondoesthings]

Thanks for confirming @roeap. I think I should be able to make a PR this weekend.