Wait for parallel builds to be cancelled on error

Previously, if building the first cluster artifact failed, skaffold
would exit immediately after. Build goroutines for other artifacts may
have still been running and not get a chance to clean up

The Kaniko build has logic to handle cancellation, but allow custom
commands to be cancelled as well

pkg/skaffold/build/custom/custom.go

@@ -54,17 +54,17 @@ func NewArtifactBuilder(pushImages bool, additionalEnv []string) *ArtifactBuilde
 // Build builds a custom artifact
 // It returns true if the image is expected to exist remotely, or false if it is expected to exist locally
 func (b *ArtifactBuilder) Build(ctx context.Context, out io.Writer, a *latest.Artifact, tag string) error {
-	cmd, err := b.retrieveCmd(a, tag)
+	cmd, err := b.retrieveCmd(ctx, a, tag)
 	if err != nil {
 		return errors.Wrap(err, "retrieving cmd")
 	}
 	return cmd.Run()
 }
 
-func (b *ArtifactBuilder) retrieveCmd(a *latest.Artifact, tag string) (*exec.Cmd, error) {
+func (b *ArtifactBuilder) retrieveCmd(ctx context.Context, a *latest.Artifact, tag string) (*exec.Cmd, error) {
 	artifact := a.CustomArtifact
 	split := strings.Split(artifact.BuildCommand, " ")
-	cmd := exec.Command(split[0], split[1:]...)
+	cmd := exec.CommandContext(ctx, split[0], split[1:]...)
 	env, err := b.retrieveEnv(a, tag)
 	if err != nil {
 		return nil, errors.Wrapf(err, "retrieving env variables for %s", a.ImageName)

pkg/skaffold/build/custom/custom_test.go

@@ -17,6 +17,7 @@ limitations under the License.
 package custom
 
 import (
+	"context"
 	"os"
 	"os/exec"
 	"reflect"
@@ -115,7 +116,7 @@ func TestRetrieveCmd(t *testing.T) {
 			t.Override(&buildContext, func(string) (string, error) { return test.artifact.Workspace, nil })
 
 			builder := NewArtifactBuilder(false, nil)
-			cmd, err := builder.retrieveCmd(test.artifact, test.tag)
+			cmd, err := builder.retrieveCmd(context.Background(), test.artifact, test.tag)
 
 			t.CheckNoError(err)
 			// cmp.Diff cannot access unexported fields in *exec.Cmd, so use reflect.DeepEqual here directly
@@ -127,7 +128,7 @@ func TestRetrieveCmd(t *testing.T) {
 }
 
 func expectedCmd(buildCommand, dir string, args, env []string) *exec.Cmd {
-	cmd := exec.Command(buildCommand, args...)
+	cmd := exec.CommandContext(context.Background(), buildCommand, args...)
 	cmd.Dir = dir
 	cmd.Env = env
 	cmd.Stdout = os.Stdout

pkg/skaffold/build/parallel.go

@@ -50,21 +50,25 @@ func InParallel(ctx context.Context, out io.Writer, tags tag.ImageTags, artifact
 		return runInSequence(ctx, out, tags, artifacts, buildArtifact)
 	}
 
+	var wg sync.WaitGroup
+	defer wg.Wait()
+
 	ctx, cancel := context.WithCancel(ctx)
 	defer cancel()
 
 	results := new(sync.Map)
 	outputs := make([]chan []byte, len(artifacts))
 
 	// Run builds in //
+	wg.Add(len(artifacts))
 	for i := range artifacts {
 		outputs[i] = make(chan []byte, buffSize)
 		r, w := io.Pipe()
 		cw := setUpColorWriter(w, out)
 
 		// Run build and write output/logs to piped writer and store build result in
 		// sync.Map
-		go runBuild(ctx, cw, tags, artifacts[i], results, buildArtifact)
+		go runBuild(ctx, &wg, cw, tags, artifacts[i], results, buildArtifact)
 		// Read build output/logs and write to buffered channel
 		go readOutputAndWriteToChannel(r, outputs[i])
 	}
@@ -73,7 +77,8 @@ func InParallel(ctx context.Context, out io.Writer, tags tag.ImageTags, artifact
 	return collectResults(out, artifacts, results, outputs)
 }
 
-func runBuild(ctx context.Context, cw io.WriteCloser, tags tag.ImageTags, artifact *latest.Artifact, results *sync.Map, build artifactBuilder) {
+func runBuild(ctx context.Context, wg *sync.WaitGroup, cw io.WriteCloser, tags tag.ImageTags, artifact *latest.Artifact, results *sync.Map, build artifactBuilder) {
+	defer wg.Done()
 	event.BuildInProgress(artifact.ImageName)
 
 	finalTag, err := getBuildResult(ctx, cw, tags, artifact, build)