Replace API call to test configuration with dummy authenticate call (#728)

## Changes

This reduces the latency of every workspace command by the duration of a
single API call to retrieve the current user (which can take up to a
full second).

Note: the better place to verify that a request can be authenticated is
the SDK itself.

## Tests

* Unit test to confirm an the empty `*http.Request` can be constructed
* Manually confirmed that the additional API call no longer happens

cmd/root/auth.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"net/http"
 	"os"
 
 	"github.com/databricks/cli/bundle"
@@ -11,7 +12,6 @@ import (
 	"github.com/databricks/cli/libs/databrickscfg"
 	"github.com/databricks/databricks-sdk-go"
 	"github.com/databricks/databricks-sdk-go/config"
-	"github.com/databricks/databricks-sdk-go/service/iam"
 	"github.com/manifoldco/promptui"
 	"github.com/spf13/cobra"
 )
@@ -19,7 +19,6 @@ import (
 // Placeholders to use as unique keys in context.Context.
 var workspaceClient int
 var accountClient int
-var currentUser int
 
 func initProfileFlag(cmd *cobra.Command) {
 	cmd.PersistentFlags().StringP("profile", "p", "", "~/.databrickscfg profile")
@@ -94,8 +93,7 @@ TRY_AUTH: // or try picking a config profile dynamically
 	if err != nil {
 		return err
 	}
-	// get current user identity also to verify validity of configuration
-	me, err := w.CurrentUser.Me(ctx)
+	err = w.Config.Authenticate(emptyHttpRequest(ctx))
 	if cmdio.IsInteractive(ctx) && errors.Is(err, config.ErrCannotConfigureAuth) {
 		profile, err := askForWorkspaceProfile()
 		if err != nil {
@@ -107,7 +105,6 @@ TRY_AUTH: // or try picking a config profile dynamically
 	if err != nil {
 		return err
 	}
-	ctx = context.WithValue(ctx, &currentUser, me)
 	ctx = context.WithValue(ctx, &workspaceClient, w)
 	cmd.SetContext(ctx)
 	return nil
@@ -194,6 +191,17 @@ func askForAccountProfile() (string, error) {
 	return profiles[i].Name, nil
 }
 
+// To verify that a client is configured correctly, we pass an empty HTTP request
+// to a client's `config.Authenticate` function. Note: this functionality
+// should be supported by the SDK itself.
+func emptyHttpRequest(ctx context.Context) *http.Request {
+	req, err := http.NewRequestWithContext(ctx, "", "", nil)
+	if err != nil {
+		panic(err)
+	}
+	return req
+}
+
 func WorkspaceClient(ctx context.Context) *databricks.WorkspaceClient {
 	w, ok := ctx.Value(&workspaceClient).(*databricks.WorkspaceClient)
 	if !ok {
@@ -209,11 +217,3 @@ func AccountClient(ctx context.Context) *databricks.AccountClient {
 	}
 	return a
 }
-
-func Me(ctx context.Context) *iam.User {
-	me, ok := ctx.Value(&currentUser).(*iam.User)
-	if !ok {
-		panic("cannot get current user. Please report it as a bug")
-	}
-	return me
-}

cmd/root/auth_test.go

@@ -0,0 +1,14 @@
+package root
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestEmptyHttpRequest(t *testing.T) {
+	ctx, _ := context.WithCancel(context.Background())
+	req := emptyHttpRequest(ctx)
+	assert.Equal(t, req.Context(), ctx)
+}