Merge pull request #1978 from thaJeztah/18.09_backport_fix_rollback_config_interpolation

[18.09 backport] Fix Rollback config type interpolation

cli/compose/loader/interpolate.go

@@ -16,6 +16,8 @@ var interpolateTypeCastMapping = map[interp.Path]interp.Cast{
 	servicePath("deploy", "replicas"):                                toInt,
 	servicePath("deploy", "update_config", "parallelism"):            toInt,
 	servicePath("deploy", "update_config", "max_failure_ratio"):      toFloat,
+	servicePath("deploy", "rollback_config", "parallelism"):          toInt,
+	servicePath("deploy", "rollback_config", "max_failure_ratio"):    toFloat,
 	servicePath("deploy", "restart_policy", "max_attempts"):          toInt,
 	servicePath("ports", interp.PathMatchList, "target"):             toInt,
 	servicePath("ports", interp.PathMatchList, "published"):          toInt,

cli/compose/loader/loader_test.go

@@ -507,7 +507,7 @@ volumes:
 
 func TestLoadWithInterpolationCastFull(t *testing.T) {
 	dict, err := ParseYAML([]byte(`
-version: "3.4"
+version: "3.7"
 services:
   web:
     configs:
@@ -524,6 +524,9 @@ services:
       update_config:
         parallelism: $theint
         max_failure_ratio: $thefloat
+      rollback_config:
+        parallelism: $theint
+        max_failure_ratio: $thefloat
       restart_policy:
         max_attempts: $theint
     ports:
@@ -574,7 +577,7 @@ networks:
 	assert.NilError(t, err)
 	expected := &types.Config{
 		Filename: "filename.yml",
-		Version:  "3.4",
+		Version:  "3.7",
 		Services: []types.ServiceConfig{
 			{
 				Name: "web",
@@ -600,6 +603,10 @@ networks:
 						Parallelism:     uint64Ptr(555),
 						MaxFailureRatio: 3.14,
 					},
+					RollbackConfig: &types.UpdateConfig{
+						Parallelism:     uint64Ptr(555),
+						MaxFailureRatio: 3.14,
+					},
 					RestartPolicy: &types.RestartPolicy{
 						MaxAttempts: uint64Ptr(555),
 					},