fix: set json-file logging driver for default log options

internal/project/logging_test.go

@@ -0,0 +1,60 @@
+package project
+
+import (
+	"testing"
+
+	"github.com/compose-spec/compose-go/v2/types"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestApplyDefaultLogging_NoServiceLogging(t *testing.T) {
+	p := &Project{
+		Project: &types.Project{
+			Services: types.Services{
+				"web": {Name: "web"},
+				"db":  {Name: "db"},
+			},
+		},
+	}
+
+	require.NoError(t, applyDefaultLogging(p))
+
+	for _, name := range []string{"web", "db"} {
+		svc := p.Services[name]
+		require.NotNil(t, svc.Logging, "service %s must get logging config", name)
+		assert.Equal(t, "json-file", svc.Logging.Driver)
+		assert.Equal(t, map[string]string{
+			"max-size": "10m",
+			"max-file": "1",
+		}, map[string]string(svc.Logging.Options))
+	}
+}
+
+func TestApplyDefaultLogging_ExistingLoggingPreserved(t *testing.T) {
+	// assign in a separate statement: ServiceConfig embeds the field via
+	// ContainerSpec, so a struct literal like ServiceConfig{Logging: ...}
+	// does not compile on compose-go v2.16+
+	svc := types.ServiceConfig{Name: "web"}
+	svc.Logging = &types.LoggingConfig{
+		Driver: "fluentd",
+		Options: map[string]string{
+			"fluentd-address": "localhost:24224",
+		},
+	}
+
+	p := &Project{
+		Project: &types.Project{
+			Services: types.Services{
+				"web": svc,
+			},
+		},
+	}
+
+	require.NoError(t, applyDefaultLogging(p))
+
+	logging := p.Services["web"].Logging
+	require.NotNil(t, logging)
+	assert.Equal(t, "fluentd", logging.Driver)
+	assert.Equal(t, map[string]string{"fluentd-address": "localhost:24224"}, map[string]string(logging.Options))
+}

internal/project/project.go

@@ -328,6 +328,7 @@ func applyDefaultLogging(p *Project) error {
 		}
 
 		svc.Logging = &types.LoggingConfig{
+			Driver: "json-file",
 			Options: map[string]string{
 				"max-size": "10m",
 				"max-file": "1",