refactor: only fetch variables if unset variables are not allowed

internal/cloud/backend_context.go

@@ -82,22 +82,6 @@ func (b *Cloud) LocalRun(op *backend.Operation) (*backend.LocalRun, statemgr.Ful
 	}
 	ret.Config = config
 
-	// The underlying API expects us to use the opaque workspace id to request
-	// variables, so we'll need to look that up using our organization name
-	// and workspace name.
-	remoteWorkspaceID, err := b.getRemoteWorkspaceID(context.Background(), op.Workspace)
-	if err != nil {
-		diags = diags.Append(fmt.Errorf("error finding remote workspace: %w", err))
-		return nil, nil, diags
-	}
-
-	log.Printf("[TRACE] cloud: retrieving variables from workspace %s/%s (%s)", remoteWorkspaceName, b.organization, remoteWorkspaceID)
-	tfeVariables, err := b.client.Variables.List(context.Background(), remoteWorkspaceID, tfe.VariableListOptions{})
-	if err != nil && err != tfe.ErrResourceNotFound {
-		diags = diags.Append(fmt.Errorf("error loading variables: %w", err))
-		return nil, nil, diags
-	}
-
 	if op.AllowUnsetVariables {
 		// If we're not going to use the variables in an operation we'll be
 		// more lax about them, stubbing out any unset ones as unknown.
@@ -105,6 +89,22 @@ func (b *Cloud) LocalRun(op *backend.Operation) (*backend.LocalRun, statemgr.Ful
 		// but not enough information to run a real operation (plan, apply, etc)
 		ret.PlanOpts.SetVariables = stubAllVariables(op.Variables, config.Module.Variables)
 	} else {
+		// The underlying API expects us to use the opaque workspace id to request
+		// variables, so we'll need to look that up using our organization name
+		// and workspace name.
+		remoteWorkspaceID, err := b.getRemoteWorkspaceID(context.Background(), op.Workspace)
+		if err != nil {
+			diags = diags.Append(fmt.Errorf("error finding remote workspace: %w", err))
+			return nil, nil, diags
+		}
+
+		log.Printf("[TRACE] cloud: retrieving variables from workspace %s/%s (%s)", remoteWorkspaceName, b.organization, remoteWorkspaceID)
+		tfeVariables, err := b.client.Variables.List(context.Background(), remoteWorkspaceID, tfe.VariableListOptions{})
+		if err != nil && err != tfe.ErrResourceNotFound {
+			diags = diags.Append(fmt.Errorf("error loading variables: %w", err))
+			return nil, nil, diags
+		}
+
 		if tfeVariables != nil {
 			if op.Variables == nil {
 				op.Variables = make(map[string]backend.UnparsedVariableValue)