BlobClient hangs if storage account doesn't exist

[aochagavia]

Problem description

I'm using BlobClient together with storage account keys. When issuing a request to the API (e.g. get_properties for a blob), the program hangs for ~80 seconds if a non-existing account name was provided.

Reproducer

This assumes you have tokio, azure_storage and azure_storage_blobs available to your crate.

use std::time::Instant;
use azure_storage::StorageCredentials;
use azure_storage_blobs::prelude::{BlobClient, BlobServiceClient};

fn main() {
    let account = "this-account-does-not-exist-1234";

    // The provided key is a real one, but has been invalidated for security
    let credentials = StorageCredentials::access_key(account, "7+iu4f92PM6yp0RcMMpRFxMHImIPNaqrxkXNVUoqZZVfdRwgXFTQYPbuUIukX8L+lqmSlVNXFB0/+AStcAn91g==");
    let client = BlobServiceClient::new(account, credentials)
        .container_client("my-container")
        .blob_client("my-blob");

    let rt = tokio::runtime::Builder::new_current_thread().enable_all().build().unwrap();
    rt.block_on(get_properties(client));
}

async fn get_properties(client: BlobClient) {
    let start = Instant::now();
    println!("Start streaming");
    let blob_stream = client.get_properties().await;
    println!("Done streaming after {:.2} seconds: success = {}", start.elapsed().as_secs_f64(), blob_stream.is_ok());
}

Probable cause

Behind the scenes, the client uses the account name to build the API url when issuing a specific request (e.g. GETting a blog would go to https://<my-account>.blob.core.windows.net/<container-name>/<blob-path>). I assume the DNS resolver hangs for some reason, instead of giving up quickly.

Suggested solution

Ensure the request times out earlier. If the problem lies indeed in DNS resolving, maybe we should give up after 5 seconds.