frontend/dockerfile/dockerignore: remove hard-coded filename from error

While this function would usually be used for read a `.dockerignore` file,
it accepts a Reader and can also be used to handle ignore patterns from
other files (e.g. `Dockerfile.dockerignore`) or other sources. The error
was also wrapped multiple times in some code-paths, which could lead to
an error being formatted as:

    failed to parse dockerignore: error reading .dockerignore: <some error>

Let's remove mention of the `.dockerignore` filename from the error, and
leave it to the caller to include the filename.

Signed-off-by: Sebastiaan van Stijn <[email protected]>

frontend/dockerfile/dockerignore/dockerignore.go

@@ -6,8 +6,6 @@ import (
 	"io"
 	"path/filepath"
 	"strings"
-
-	"github.com/pkg/errors"
 )
 
 // ReadAll reads an ignore file from a reader and returns the list of file
@@ -69,7 +67,7 @@ func ReadAll(reader io.Reader) ([]string, error) {
 		excludes = append(excludes, pattern)
 	}
 	if err := scanner.Err(); err != nil {
-		return nil, errors.Wrap(err, "error reading .dockerignore")
+		return nil, err
 	}
 	return excludes, nil
 }

frontend/dockerui/namedcontext.go

@@ -208,7 +208,7 @@ func (bc *Client) namedContextRecursive(ctx context.Context, name string, nameWi
 			if len(dt) != 0 {
 				excludes, err = dockerignore.ReadAll(bytes.NewBuffer(dt))
 				if err != nil {
-					return nil, nil, err
+					return nil, nil, errors.Wrapf(err, "error parsing %s", DefaultDockerignoreName)
 				}
 			}
 		}