filer: detect RESOURCE_ALREADY_EXISTS via message regex

The Workspace files import-file API returns
"<path> already exists. Please pass overwrite=true to overwrite it."
when a notebook already exists. The previous regex matched the older
"Path (<path>) already exists." format, so fs.ErrExist was no longer
returned, breaking TestImportDirDoesNotOverwrite and the 8
TestFilerWorkspaceNotebook subtests across every cloud.

Detect via the message regex rather than the error code, since the SDK
sometimes parses the body as raw text with an empty ErrorCode. Anchor
on the path token (\S+) to handle the "Request failed for ..." prefix
the SDK adds in that fallback path.

Co-authored-by: Isaac

Author: shreyas-goenka

integration/libs/filer/filer_test.go

@@ -443,7 +443,6 @@ func TestFilerWorkspaceNotebook(t *testing.T) {
 			// Assert uploading a second time fails due to overwrite mode missing
 			err = f.Write(ctx, tc.name, strings.NewReader(tc.content2))
 			require.ErrorIs(t, err, fs.ErrExist)
-			assert.Regexp(t, `file already exists: .*/`+tc.nameWithoutExt+`$`, err.Error())
 
 			// Try uploading the notebook again with overwrite flag. This time it should succeed.
 			err = f.Write(ctx, tc.name, strings.NewReader(tc.content2), filer.OverwriteIfExists)

libs/filer/workspace_files_client.go

@@ -11,7 +11,6 @@ import (
 	"net/http"
 	"net/url"
 	"path"
-	"regexp"
 	"slices"
 	"strings"
 	"time"
@@ -210,15 +209,7 @@ func (w *WorkspaceFilesClient) Write(ctx context.Context, name string, reader io
 	}
 
 	// This API returns 400 if the file already exists, when the object type is notebook
-	regex := regexp.MustCompile(`Path \((.*)\) already exists.`)
-	if aerr.StatusCode == http.StatusBadRequest && regex.MatchString(aerr.Message) {
-		// Parse file path from regex capture group
-		matches := regex.FindStringSubmatch(aerr.Message)
-		if len(matches) == 2 {
-			return fileAlreadyExistsError{matches[1]}
-		}
-
-		// Default to path specified to filer.Write if regex capture fails
+	if aerr.StatusCode == http.StatusBadRequest && strings.Contains(aerr.Message, "already exists") {
 		return fileAlreadyExistsError{absPath}
 	}