Update recorder to lazy create file.

Currently the resolver command creates the image-refs file on
initilization. This causes git to be dirty during builds. This change moves the
file creation to be in the recorder itself and on the first time the Publish()
method is called. This happens after the build so git is clean. This will mean
that any errors on file creation will be reported after the build rather than
before.

Signed-off-by: Jeff Mendoza <[email protected]>

Author: jeffmendoza

pkg/commands/resolver.go

@@ -266,11 +266,7 @@ func makePublisher(po *options.PublishOptions) (publish.Interface, error) {
 	}
 
 	if po.ImageRefsFile != "" {
-		f, err := os.OpenFile(po.ImageRefsFile, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0644)
-		if err != nil {
-			return nil, err
-		}
-		innerPublisher, err = publish.NewRecorder(innerPublisher, f)
+		innerPublisher, err = publish.NewRecorder(innerPublisher, po.ImageRefsFile)
 		if err != nil {
 			return nil, err
 		}

pkg/publish/recorder.go

@@ -17,6 +17,7 @@ package publish
 import (
 	"context"
 	"io"
+	"os"
 	"strings"
 
 	"github.com/google/go-containerregistry/pkg/name"
@@ -29,19 +30,20 @@ import (
 // recorder wraps a publisher implementation in a layer that recordes the published
 // references to an io.Writer.
 type recorder struct {
-	inner Interface
-	wc    io.Writer
+	inner    Interface
+	fileName string
+	wc       io.Writer
 }
 
 // recorder implements Interface
 var _ Interface = (*recorder)(nil)
 
 // NewRecorder wraps the provided publish.Interface in an implementation that
 // records publish results to an io.Writer.
-func NewRecorder(inner Interface, wc io.Writer) (Interface, error) {
+func NewRecorder(inner Interface, name string) (Interface, error) {
 	return &recorder{
-		inner: inner,
-		wc:    wc,
+		inner:    inner,
+		fileName: name,
 	}, nil
 }
 
@@ -70,6 +72,14 @@ func (r *recorder) Publish(ctx context.Context, br build.Result, ref string) (na
 		references = append(references, result.String())
 	}
 
+	if r.wc == nil {
+		f, err := os.OpenFile(r.fileName, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0644)
+		if err != nil {
+			return nil, err
+		}
+		r.wc = f
+	}
+
 	if _, err := r.wc.Write([]byte(strings.Join(references, "\n") + "\n")); err != nil {
 		return nil, err
 	}

pkg/publish/recorder_test.go

@@ -15,8 +15,9 @@
 package publish
 
 import (
-	"bytes"
 	"context"
+	"os"
+	"path"
 	"strings"
 	"testing"
 
@@ -50,9 +51,10 @@ func TestRecorder(t *testing.T) {
 		return repo.Context().Digest(h.String()), nil
 	}}
 
-	buf := bytes.NewBuffer(nil)
+	dir := t.TempDir()
+	file := path.Join(dir, "testfile")
 
-	recorder, err := NewRecorder(inner, buf)
+	recorder, err := NewRecorder(inner, file)
 	if err != nil {
 		t.Fatalf("NewRecorder() = %v", err)
 	}
@@ -82,7 +84,11 @@ func TestRecorder(t *testing.T) {
 		t.Errorf("recorder.Close() = %v", err)
 	}
 
-	refs := strings.Split(strings.TrimSpace(buf.String()), "\n")
+	buf, err := os.ReadFile(file)
+	if err != nil {
+		t.Fatalf("os.ReadFile() = %v", err)
+	}
+	refs := strings.Split(strings.TrimSpace(string(buf)), "\n")
 
 	if want, got := len(refs), 5; got != want {
 		t.Errorf("len(refs) = %d, wanted %d", got, want)