bake: check for empty build network with compose

Signed-off-by: CrazyMax <1951866+crazy-max@users.noreply.github.com>

bake/compose.go

@@ -102,6 +102,12 @@ func ParseCompose(cfgs []composetypes.ConfigFile, envs map[string]string) (*Conf
 				shmSize = &shmSizeStr
 			}
 
+			var networkModeP *string
+			if s.Build.Network != "" {
+				networkMode := s.Build.Network
+				networkModeP = &networkMode
+			}
+
 			var ulimits []string
 			if s.Build.Ulimits != nil {
 				for n, u := range s.Build.Ulimits {
@@ -154,7 +160,7 @@ func ParseCompose(cfgs []composetypes.ConfigFile, envs map[string]string) (*Conf
 				})),
 				CacheFrom:   s.Build.CacheFrom,
 				CacheTo:     s.Build.CacheTo,
-				NetworkMode: &s.Build.Network,
+				NetworkMode: networkModeP,
 				SSH:         ssh,
 				Secrets:     secrets,
 				ShmSize:     shmSize,

tests/bake.go

@@ -63,22 +63,44 @@ var bakeTests = []func(t *testing.T, sb integration.Sandbox){
 }
 
 func testBakePrint(t *testing.T, sb integration.Sandbox) {
-	dockerfile := []byte(`
-FROM busybox
-ARG HELLO
-RUN echo "Hello ${HELLO}"
-	`)
-	bakefile := []byte(`
+	testCases := []struct {
+		name string
+		f    string
+		dt   []byte
+	}{
+		{
+			"HCL",
+			"docker-bake.hcl",
+			[]byte(`
 target "build" {
   args = {
     HELLO = "foo"
   }
 }
-`)
+`)},
+		{
+			"Compose",
+			"compose.yml",
+			[]byte(`
+services:
+  build:
+    build:
+      context: .
+      args:
+        HELLO: foo
+`)},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
 			dir := tmpdir(
 				t,
-		fstest.CreateFile("docker-bake.hcl", bakefile, 0600),
-		fstest.CreateFile("Dockerfile", dockerfile, 0600),
+				fstest.CreateFile(tc.f, tc.dt, 0600),
+				fstest.CreateFile("Dockerfile", []byte(`
+FROM busybox
+ARG HELLO
+RUN echo "Hello ${HELLO}"
+	`), 0600),
 			)
 
 			cmd := buildxCmd(sb, withDir(dir), withArgs("bake", "--print", "build"))
@@ -123,6 +145,8 @@ target "build" {
   }
 }
 `, stdout.String())
+		})
+	}
 }
 
 func testBakeLocal(t *testing.T, sb integration.Sandbox) {