script: allow storing lua tables into state bag (#3005)

Signed-off-by: Alexander Yastrebov <[email protected]>

docs/reference/scripts.md

@@ -180,8 +180,8 @@ Path("/api/:id") -> lua("function request(ctx, params); print(ctx.path_param.id)
 
 ## StateBag
 
-The state bag can be used to pass values from one filter to another in the same
-chain. It is shared by all filters in one request.
+The state bag can be used to pass string, number and table values from one filter to another in the same
+chain. It is shared by all filters in one request (lua table values are only available to lua filters).
 ```lua
 function request(ctx, params)
     -- the value of "mykey" will be available to all filters in the chain now:

script/script.go

@@ -609,6 +609,8 @@ func getStateBag(f filters.FilterContext) func(*lua.LState) int {
 			s.Push(lua.LNumber(res))
 		case float64:
 			s.Push(lua.LNumber(res))
+		case *lua.LTable:
+			s.Push(res) // load *lua.LTable as is
 		default:
 			return 0
 		}
@@ -626,6 +628,8 @@ func setStateBag(f filters.FilterContext) func(*lua.LState) int {
 			res = string(val.(lua.LString))
 		case lua.LTNumber:
 			res = float64(val.(lua.LNumber))
+		case lua.LTTable:
+			res = val // store *lua.LTable as is
 		default:
 			// TODO(sszuecs): https://github.com/zalando/skipper/issues/1487
 			// s.RaiseError("unsupported state bag value type %v, need a string or a number", val.Type())

script/script_test.go

@@ -822,18 +822,22 @@ func ExampleGetMissingStateBag() {
 	// nil
 }
 
-const SetUnsupportedStateBag = `
+const SetStateBagTable = `
 function request(ctx, params)
-	ctx.state_bag.unsupported = {}
-	print("ok")
-end`
+	ctx.state_bag.table = {foo="bar"}
+end
+
+function response(ctx, params)
+	print(ctx.state_bag.table.foo)
+end
+`
 
-func ExampleSetUnsupportedStateBag() {
+func ExampleSetStateBagTable() {
 	runExample(&testContext{
-		script: SetUnsupportedStateBag,
+		script: SetStateBagTable,
 	})
 	// Output:
-	// ok
+	// bar
 }
 
 func newFilter(opts LuaOptions, script string, params ...string) (filters.Filter, error) {