Lack of parameter "azure domain" when use azure blob storage as a repository

[diddowill]

Output of restic version

restic 0.9.5 compiled with go1.11.5 on linux/amd64

Describe the issue

According to the manual here (https://restic.readthedocs.io/en/stable/030_preparing_a_new_repo.html#microsoft-azure-blob-storage),
we need to provide account name and access key when use azure block storage as a repository.
But that does not work if you azure domain is not azure global, like azure China and azure Germany.
Error is returned as below:

storage: service returned error: StatusCode=403, ErrorCode=AuthenticationFailed, ErrorMessage=Server failed to authenticate the request. Make sure the value of Authorization header is formed correctly including the signature.

The solution from Azure tech. support is, we must specify azure domain in this case as their tool Azure Storage Explore does.

[whs-dot-hk]

hi

looks like the NewBasicClient

restic/internal/backend/azure/azure.go

Line 38 in 604b18a

client, err := storage.NewBasicClient(cfg.AccountName, cfg.AccountKey)

is used here

which uses the default base url

restic/vendor/github.com/Azure/azure-sdk-for-go/storage/client.go

Line 45 in 604b18a

DefaultBaseURL = "core.windows.net"

[shtratos]

You can workaround this by using rclone backend:
https://restic.readthedocs.io/en/latest/030_preparing_a_new_repo.html#other-services-via-rclone

rclone supports specifying the azure endpoint via --azureblob-endpoint
https://rclone.org/azureblob/#advanced-options

[MichaelEischer]

Adding a configuration parameter for the azure backend that allows overriding the default BaseURL should be enough to solve this issue.

[arjunajesh]

@MichaelEischer I would like to work on this issue.
Just to be sure, should the domain be passed through an env variable (for example AZURE_DOMAIN)

[arjunajesh]

I believe that I have a solution for this issue. Does anyone have a Chinese Azure account for me to test my fix?