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lua.go
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lua.go
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package lua
import (
"context"
"encoding/json"
"fmt"
"os"
"path/filepath"
"time"
"github.com/gobuffalo/packr"
lua "github.com/yuin/gopher-lua"
"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
luajson "layeh.com/gopher-json"
appv1 "github.com/argoproj/argo-cd/pkg/apis/application/v1alpha1"
)
const (
incorrectReturnType = "expect %s output from Lua script, not %s"
invalidHealthStatus = "Lua returned an invalid health status"
resourceCustomizationBuiltInPath = "../../resource_customizations"
healthScriptFile = "health.lua"
actionScriptFile = "action.lua"
actionDiscoveryScriptFile = "discovery.lua"
)
var (
box packr.Box
)
func init() {
box = packr.NewBox(resourceCustomizationBuiltInPath)
}
// VM Defines a struct that implements the luaVM
type VM struct {
ResourceOverrides map[string]appv1.ResourceOverride
// UseOpenLibs flag to enable open libraries. Libraries are always disabled while running, but enabled during testing to allow the use of print statements
UseOpenLibs bool
}
func (vm VM) runLua(obj *unstructured.Unstructured, script string) (*lua.LState, error) {
l := lua.NewState(lua.Options{
SkipOpenLibs: !vm.UseOpenLibs,
})
defer l.Close()
// Opens table library to allow access to functions to manipulate tables
for _, pair := range []struct {
n string
f lua.LGFunction
}{
{lua.LoadLibName, lua.OpenPackage},
{lua.BaseLibName, lua.OpenBase},
{lua.TabLibName, lua.OpenTable},
// load our 'safe' version of the os library
{lua.OsLibName, OpenSafeOs},
} {
if err := l.CallByParam(lua.P{
Fn: l.NewFunction(pair.f),
NRet: 0,
Protect: true,
}, lua.LString(pair.n)); err != nil {
panic(err)
}
}
// preload our 'safe' version of the os library. Allows the 'local os = require("os")' to work
l.PreloadModule(lua.OsLibName, SafeOsLoader)
ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
defer cancel()
l.SetContext(ctx)
objectValue := decodeValue(l, obj.Object)
l.SetGlobal("obj", objectValue)
err := l.DoString(script)
return l, err
}
// ExecuteHealthLua runs the lua script to generate the health status of a resource
func (vm VM) ExecuteHealthLua(obj *unstructured.Unstructured, script string) (*appv1.HealthStatus, error) {
l, err := vm.runLua(obj, script)
if err != nil {
return nil, err
}
returnValue := l.Get(-1)
if returnValue.Type() == lua.LTTable {
jsonBytes, err := luajson.Encode(returnValue)
if err != nil {
return nil, err
}
healthStatus := &appv1.HealthStatus{}
err = json.Unmarshal(jsonBytes, healthStatus)
if err != nil {
return nil, err
}
if !isValidHealthStatusCode(healthStatus.Status) {
return &appv1.HealthStatus{
Status: appv1.HealthStatusUnknown,
Message: invalidHealthStatus,
}, nil
}
return healthStatus, nil
}
return nil, fmt.Errorf(incorrectReturnType, "table", returnValue.Type().String())
}
// GetHealthScript attempts to read lua script from config and then filesystem for that resource
func (vm VM) GetHealthScript(obj *unstructured.Unstructured) (string, error) {
key := getConfigMapKey(obj)
if script, ok := vm.ResourceOverrides[key]; ok && script.HealthLua != "" {
return script.HealthLua, nil
}
return vm.getPredefinedLuaScripts(key, healthScriptFile)
}
func (vm VM) ExecuteResourceAction(obj *unstructured.Unstructured, script string) (*unstructured.Unstructured, error) {
l, err := vm.runLua(obj, script)
if err != nil {
return nil, err
}
returnValue := l.Get(-1)
if returnValue.Type() == lua.LTTable {
jsonBytes, err := luajson.Encode(returnValue)
if err != nil {
return nil, err
}
newObj, err := appv1.UnmarshalToUnstructured(string(jsonBytes))
if err != nil {
return nil, err
}
cleanedNewObj := cleanReturnedObj(newObj.Object, obj.Object)
newObj.Object = cleanedNewObj
return newObj, nil
}
return nil, fmt.Errorf(incorrectReturnType, "table", returnValue.Type().String())
}
// cleanReturnedObj Lua cannot distinguish an empty table as an array or map, and the library we are using choose to
// decoded an empty table into an empty array. This function prevents the lua scripts from unintentionally changing an
// empty struct into empty arrays
func cleanReturnedObj(newObj, obj map[string]interface{}) map[string]interface{} {
mapToReturn := newObj
for key := range obj {
if newValueInterface, ok := newObj[key]; ok {
oldValueInterface, ok := obj[key]
if !ok {
continue
}
switch newValue := newValueInterface.(type) {
case map[string]interface{}:
if oldValue, ok := oldValueInterface.(map[string]interface{}); ok {
convertedMap := cleanReturnedObj(newValue, oldValue)
mapToReturn[key] = convertedMap
}
case []interface{}:
switch oldValue := oldValueInterface.(type) {
case map[string]interface{}:
if len(newValue) == 0 {
mapToReturn[key] = oldValue
}
case []interface{}:
newArray := cleanReturnedArray(newValue, oldValue)
mapToReturn[key] = newArray
}
}
}
}
return mapToReturn
}
// cleanReturnedArray allows Argo CD to recurse into nested arrays when checking for unintentional empty struct to
// empty array conversions.
func cleanReturnedArray(newObj, obj []interface{}) []interface{} {
arrayToReturn := newObj
for i := range newObj {
switch newValue := newObj[i].(type) {
case map[string]interface{}:
if oldValue, ok := obj[i].(map[string]interface{}); ok {
convertedMap := cleanReturnedObj(newValue, oldValue)
arrayToReturn[i] = convertedMap
}
case []interface{}:
if oldValue, ok := obj[i].([]interface{}); ok {
convertedMap := cleanReturnedArray(newValue, oldValue)
arrayToReturn[i] = convertedMap
}
}
}
return arrayToReturn
}
func (vm VM) ExecuteResourceActionDiscovery(obj *unstructured.Unstructured, script string) ([]appv1.ResourceAction, error) {
l, err := vm.runLua(obj, script)
if err != nil {
return nil, err
}
returnValue := l.Get(-1)
if returnValue.Type() == lua.LTTable {
jsonBytes, err := luajson.Encode(returnValue)
if err != nil {
return nil, err
}
availableActions := make([]appv1.ResourceAction, 0)
if noAvailableActions(jsonBytes) {
return availableActions, nil
}
availableActionsMap := make(map[string]interface{})
err = json.Unmarshal(jsonBytes, &availableActionsMap)
if err != nil {
return nil, err
}
for key := range availableActionsMap {
value := availableActionsMap[key]
resourceAction := appv1.ResourceAction{Name: key}
if emptyResourceActionFromLua(value) {
availableActions = append(availableActions, resourceAction)
continue
}
resourceActionBytes, err := json.Marshal(value)
if err != nil {
return nil, err
}
err = json.Unmarshal(resourceActionBytes, &resourceAction)
if err != nil {
return nil, err
}
availableActions = append(availableActions, resourceAction)
}
return availableActions, err
}
return nil, fmt.Errorf(incorrectReturnType, "table", returnValue.Type().String())
}
func emptyResourceActionFromLua(i interface{}) bool {
_, ok := i.([]interface{})
return ok
}
func noAvailableActions(jsonBytes []byte) bool {
// When the Lua script returns an empty table, it is decoded as a empty array.
return string(jsonBytes) == "[]"
}
func (vm VM) GetResourceActionDiscovery(obj *unstructured.Unstructured) (string, error) {
key := getConfigMapKey(obj)
override, ok := vm.ResourceOverrides[key]
if ok && override.Actions != "" {
actions, err := override.GetActions()
if err != nil {
return "", err
}
return actions.ActionDiscoveryLua, nil
}
discoveryKey := fmt.Sprintf("%s/actions/", key)
discoveryScript, err := vm.getPredefinedLuaScripts(discoveryKey, actionDiscoveryScriptFile)
if err != nil {
return "", err
}
return discoveryScript, nil
}
// GetResourceAction attempts to read lua script from config and then filesystem for that resource
func (vm VM) GetResourceAction(obj *unstructured.Unstructured, actionName string) (appv1.ResourceActionDefinition, error) {
key := getConfigMapKey(obj)
override, ok := vm.ResourceOverrides[key]
if ok && override.Actions != "" {
actions, err := override.GetActions()
if err != nil {
return appv1.ResourceActionDefinition{}, err
}
for _, action := range actions.Definitions {
if action.Name == actionName {
return action, nil
}
}
}
actionKey := fmt.Sprintf("%s/actions/%s", key, actionName)
actionScript, err := vm.getPredefinedLuaScripts(actionKey, actionScriptFile)
if err != nil {
return appv1.ResourceActionDefinition{}, err
}
return appv1.ResourceActionDefinition{
Name: actionName,
ActionLua: actionScript,
}, nil
}
func getConfigMapKey(obj *unstructured.Unstructured) string {
gvk := obj.GroupVersionKind()
if gvk.Group == "" {
return gvk.Kind
}
return fmt.Sprintf("%s/%s", gvk.Group, gvk.Kind)
}
func (vm VM) getPredefinedLuaScripts(objKey string, scriptFile string) (string, error) {
data, err := box.MustBytes(filepath.Join(objKey, scriptFile))
if err != nil {
if os.IsNotExist(err) {
return "", nil
}
return "", err
}
return string(data), nil
}
func isValidHealthStatusCode(statusCode string) bool {
switch statusCode {
case appv1.HealthStatusUnknown, appv1.HealthStatusProgressing, appv1.HealthStatusSuspended, appv1.HealthStatusHealthy, appv1.HealthStatusDegraded, appv1.HealthStatusMissing:
return true
}
return false
}
// Took logic from the link below and added the int, int32, and int64 types since the value would have type int64
// while actually running in the controller and it was not reproducible through testing.
// https://github.com/layeh/gopher-json/blob/97fed8db84274c421dbfffbb28ec859901556b97/json.go#L154
func decodeValue(L *lua.LState, value interface{}) lua.LValue {
switch converted := value.(type) {
case bool:
return lua.LBool(converted)
case float64:
return lua.LNumber(converted)
case string:
return lua.LString(converted)
case json.Number:
return lua.LString(converted)
case int:
return lua.LNumber(converted)
case int32:
return lua.LNumber(converted)
case int64:
return lua.LNumber(converted)
case []interface{}:
arr := L.CreateTable(len(converted), 0)
for _, item := range converted {
arr.Append(decodeValue(L, item))
}
return arr
case map[string]interface{}:
tbl := L.CreateTable(0, len(converted))
for key, item := range converted {
tbl.RawSetH(lua.LString(key), decodeValue(L, item))
}
return tbl
case nil:
return lua.LNil
}
return lua.LNil
}