compute service hash with a default DeployConfig

Signed-off-by: Nicolas De Loof <nicolas.deloof@gmail.com>

pkg/compose/hash.go

@@ -28,11 +28,12 @@ func ServiceHash(o types.ServiceConfig) (string, error) {
 	// remove the Build config when generating the service hash
 	o.Build = nil
 	o.PullPolicy = ""
-	o.Scale = 1
-	if o.Deploy != nil {
-		var one uint64 = 1
-		o.Deploy.Replicas = &one
+	if o.Deploy == nil {
+		o.Deploy = &types.DeployConfig{}
 	}
+	o.Scale = 1
+	var one uint64 = 1
+	o.Deploy.Replicas = &one
 	bytes, err := json.Marshal(o)
 	if err != nil {
 		return "", err

pkg/e2e/up_test.go

@@ -23,13 +23,14 @@ import (
 	"context"
 	"os"
 	"os/exec"
+	"strings"
 	"syscall"
 	"testing"
 	"time"
 
 	"github.com/docker/compose/v2/pkg/utils"
-	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"gotest.tools/v3/assert"
 	"gotest.tools/v3/icmd"
 )
 
@@ -79,7 +80,7 @@ func TestUpDependenciesNotStopped(t *testing.T) {
 	defer cancel()
 
 	cmd, err := StartWithNewGroupID(ctx, testCmd, upOut, nil)
-	assert.NoError(t, err, "Failed to run compose up")
+	assert.NilError(t, err, "Failed to run compose up")
 
 	t.Log("Waiting for containers to be in running state")
 	upOut.RequireEventuallyContains(t, "hello app")
@@ -138,3 +139,17 @@ func TestUpWithDependencyExit(t *testing.T) {
 		res.Assert(t, icmd.Expected{ExitCode: 1, Err: "dependency failed to start: container dependencies-db-1 exited (1)"})
 	})
 }
+
+func TestScaleDoesntRecreate(t *testing.T) {
+	c := NewCLI(t)
+	const projectName = "compose-e2e-scale"
+	t.Cleanup(func() {
+		c.RunDockerComposeCmd(t, "--project-name", projectName, "down")
+	})
+
+	c.RunDockerComposeCmd(t, "-f", "fixtures/simple-composefile/compose.yaml", "--project-name", projectName, "up", "-d")
+
+	res := c.RunDockerComposeCmd(t, "-f", "fixtures/simple-composefile/compose.yaml", "--project-name", projectName, "up", "--scale", "simple=2", "-d")
+	assert.Check(t, !strings.Contains(res.Combined(), "Recreated"))
+
+}