bake: compose parser should only error if there are neither build nor image fields

Signed-off-by: Tibor Vass <tibor@docker.com>

bake/compose.go

@@ -2,6 +2,7 @@ package bake
 
 import (
 	"fmt"
+	"reflect"
 
 	"github.com/docker/cli/cli/compose/loader"
 	composetypes "github.com/docker/cli/cli/compose/types"
@@ -28,6 +29,7 @@ func ParseCompose(dt []byte) (*Config, error) {
 	}
 
 	var c Config
+	var zeroBuildConfig composetypes.BuildConfig
 	if len(cfg.Services) > 0 {
 		c.Group = map[string]Group{}
 		c.Target = map[string]Target{}
@@ -36,6 +38,14 @@ func ParseCompose(dt []byte) (*Config, error) {
 
 		for _, s := range cfg.Services {
 
+			if reflect.DeepEqual(s.Build, zeroBuildConfig) {
+				// if not make sure they're setting an image or it's invalid d-c.yml
+				if s.Image == "" {
+					return nil, fmt.Errorf("compose file invalid: service %s has neither an image nor a build context specified. At least one must be provided.", s.Name)
+				}
+				continue
+			}
+
 			var contextPathP *string
 			if s.Build.Context != "" {
 				contextPath := s.Build.Context
@@ -46,14 +56,6 @@ func ParseCompose(dt []byte) (*Config, error) {
 				dockerfilePath := s.Build.Dockerfile
 				dockerfilePathP = &dockerfilePath
 			}
-			// Check if there's actually a dockerfile mentioned
-			if dockerfilePathP == nil && contextPathP == nil {
-				// if not make sure they're setting an image or it's invalid d-c.yml
-				if s.Image == "" {
-					return nil, fmt.Errorf("Compose file invalid: Service %s has neither an image nor a build context specified. At least one must be provided.", s.Name)
-				}
-				break
-			}
 			g.Targets = append(g.Targets, s.Name)
 			t := Target{
 				Context:    contextPathP,

bake/compose_test.go

@@ -53,7 +53,6 @@ services:
 	c, err := ParseCompose(dt)
 	require.NoError(t, err)
 	require.Equal(t, 1, len(c.Group))
-
 }
 
 func TestParseComposeTarget(t *testing.T) {
@@ -78,7 +77,7 @@ services:
 	require.Equal(t, "webapp", *c.Target["webapp"].Target)
 }
 
-func TestBogusCompose(t *testing.T) {
+func TestComposeBuildWithoutContext(t *testing.T) {
 	var dt = []byte(`
 version: "3.7"
 
@@ -92,6 +91,27 @@ services:
       target: webapp
 `)
 
+	c, err := ParseCompose(dt)
+	require.NoError(t, err)
+	require.Equal(t, "db", *c.Target["db"].Target)
+	require.Equal(t, "webapp", *c.Target["webapp"].Target)
+}
+
+func TestBogusCompose(t *testing.T) {
+	var dt = []byte(`
+version: "3.7"
+
+services:
+  db:
+    labels:
+      - "foo"
+  webapp:
+    build:
+      context: .
+      target: webapp
+`)
+
 	_, err := ParseCompose(dt)
 	require.Error(t, err)
+	require.Contains(t, err.Error(), "has neither an image nor a build context specified. At least one must be provided")
 }