azureblob: add --azureblob-use-az to force the use of the Azure CLI for auth

Setting this can be useful if you wish to use the az CLI on a host with
a System Managed Identity that you do not want to use.

Fixes #8078

backend/azureblob/azureblob.go

@@ -259,6 +259,20 @@ msi_client_id, or msi_mi_res_id parameters.`,
 			Help:     "Uses local storage emulator if provided as 'true'.\n\nLeave blank if using real azure storage endpoint.",
 			Default:  false,
 			Advanced: true,
+		}, {
+			Name: "use_az",
+			Help: `Use Azure CLI tool az for authentication
+
+Set to use the [Azure CLI tool az](https://learn.microsoft.com/en-us/cli/azure/)
+as the sole means of authentication.
+
+Setting this can be useful if you wish to use the az CLI on a host with
+a System Managed Identity that you do not want to use.
+
+Don't set env_auth at the same time.
+`,
+			Default:  false,
+			Advanced: true,
 		}, {
 			Name:     "endpoint",
 			Help:     "Endpoint for the service.\n\nLeave blank normally.",
@@ -459,6 +473,7 @@ type Options struct {
 	MSIObjectID                string               `config:"msi_object_id"`
 	MSIClientID                string               `config:"msi_client_id"`
 	MSIResourceID              string               `config:"msi_mi_res_id"`
+	UseAZ                      bool                 `config:"use_az"`
 	Endpoint                   string               `config:"endpoint"`
 	ChunkSize                  fs.SizeSuffix        `config:"chunk_size"`
 	UploadConcurrency          int                  `config:"upload_concurrency"`
@@ -893,6 +908,12 @@ func NewFs(ctx context.Context, name, root string, m configmap.Mapper) (fs.Fs, e
 		if err != nil {
 			return nil, fmt.Errorf("failed to acquire MSI token: %w", err)
 		}
+	case opt.UseAZ:
+		var options = azidentity.AzureCLICredentialOptions{}
+		cred, err = azidentity.NewAzureCLICredential(&options)
+		if err != nil {
+			return nil, fmt.Errorf("failed to create Azure CLI credentials: %w", err)
+		}
 	case opt.Account != "":
 		// Anonymous access
 		anonymous = true

docs/content/azureblob.md

@@ -297,6 +297,16 @@ be explicitly specified using exactly one of the `msi_object_id`,
 If none of `msi_object_id`, `msi_client_id`, or `msi_mi_res_id` is
 set, this is is equivalent to using `env_auth`.
 
+#### Azure CLI tool `az` {#use_az}
+
+Set to use the [Azure CLI tool `az`](https://learn.microsoft.com/en-us/cli/azure/)
+as the sole means of authentication.
+
+Setting this can be useful if you wish to use the `az` CLI on a host with
+a System Managed Identity that you do not want to use.
+
+Don't set `env_auth` at the same time.
+
 #### Anonymous {#anonymous}
 
 If you want to access resources with public anonymous access then set