build: fix partial multi-node image pushes

build/build.go

@@ -432,6 +432,41 @@ func toRepoOnly(in string) (string, error) {
 	return strings.Join(out, ","), nil
 }
 
+func prepareMultiDriverExports(so *client.SolveOpt, pushNames *string, insecurePush *bool) error {
+	var pushPrepared bool
+	for i := range so.Exports {
+		e := &so.Exports[i]
+		switch e.Type {
+		case "oci", "tar":
+			return errors.Errorf("%s for multi-node builds currently not supported", e.Type)
+		case "image":
+			if pushPrepared {
+				continue
+			}
+			if ok, _ := strconv.ParseBool(e.Attrs["push"]); !ok {
+				continue
+			}
+			if *pushNames == "" {
+				*pushNames = e.Attrs["name"]
+				if *pushNames == "" {
+					return errors.Errorf("tag is needed when pushing to registry")
+				}
+				if ok, _ := strconv.ParseBool(e.Attrs["registry.insecure"]); ok {
+					*insecurePush = true
+				}
+			}
+			names, err := toRepoOnly(e.Attrs["name"])
+			if err != nil {
+				return err
+			}
+			e.Attrs["name"] = names
+			e.Attrs["push-by-digest"] = "true"
+			pushPrepared = true
+		}
+	}
+	return nil
+}
+
 type (
 	EvaluateFunc func(ctx context.Context, name string, c gateway.Client, res *gateway.Result, opt Options) error
 	Handler      struct {
@@ -566,30 +601,8 @@ func BuildWithResultHandler(ctx context.Context, nodes []builder.Node, opts map[
 				node := dp.Node()
 				so := reqForNodes[k][i].so
 				if multiDriver {
-					for i, e := range so.Exports {
-						switch e.Type {
-						case "oci", "tar":
-							return errors.Errorf("%s for multi-node builds currently not supported", e.Type)
-						case "image":
-							if pushNames == "" && e.Attrs["push"] != "" {
-								if ok, _ := strconv.ParseBool(e.Attrs["push"]); ok {
-									pushNames = e.Attrs["name"]
-									if pushNames == "" {
-										return errors.Errorf("tag is needed when pushing to registry")
-									}
-									names, err := toRepoOnly(e.Attrs["name"])
-									if err != nil {
-										return err
-									}
-									if ok, _ := strconv.ParseBool(e.Attrs["registry.insecure"]); ok {
-										insecurePush = true
-									}
-									e.Attrs["name"] = names
-									e.Attrs["push-by-digest"] = "true"
-									so.Exports[i].Attrs = e.Attrs
-								}
-							}
-						}
+					if err := prepareMultiDriverExports(so, &pushNames, &insecurePush); err != nil {
+						return err
 					}
 				}
 

build/build_test.go

@@ -35,6 +35,48 @@ func (d warnOutputDriver) IsMobyDriver() bool {
 	return d.moby
 }
 
+func TestPrepareMultiDriverExportsForEveryNode(t *testing.T) {
+	const taggedName = "registry.example.com/user/app:latest"
+	const secondaryName = "registry.example.com/user/secondary:latest"
+	newSolveOpt := func() *client.SolveOpt {
+		return &client.SolveOpt{
+			Exports: []client.ExportEntry{
+				{
+					Type: "image",
+					Attrs: map[string]string{
+						"name":              taggedName,
+						"push":              "true",
+						"registry.insecure": "true",
+					},
+				},
+				{
+					Type: "image",
+					Attrs: map[string]string{
+						"name": secondaryName,
+						"push": "true",
+					},
+				},
+			},
+		}
+	}
+	solveOpts := []*client.SolveOpt{newSolveOpt(), newSolveOpt()}
+
+	var pushNames string
+	var insecurePush bool
+	for _, so := range solveOpts {
+		require.NoError(t, prepareMultiDriverExports(so, &pushNames, &insecurePush))
+	}
+
+	require.Equal(t, taggedName, pushNames)
+	require.True(t, insecurePush)
+	for _, so := range solveOpts {
+		require.Equal(t, "registry.example.com/user/app", so.Exports[0].Attrs["name"])
+		require.Equal(t, "true", so.Exports[0].Attrs["push-by-digest"])
+		require.Equal(t, secondaryName, so.Exports[1].Attrs["name"])
+		require.NotContains(t, so.Exports[1].Attrs, "push-by-digest")
+	}
+}
+
 func TestWarnOnNoOutput(t *testing.T) {
 	cloudNodes := []builder.Node{{Driver: newWarnOutputDriver("cloud", false)}}
 	mobyNodes := []builder.Node{{Driver: newWarnOutputDriver("docker", true)}}