nativefuncs.go

// Copyright 2017 The kubecfg authors
//
//
//    Licensed under the Apache License, Version 2.0 (the "License");
//    you may not use this file except in compliance with the License.
//    You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
//    Unless required by applicable law or agreed to in writing, software
//    distributed under the License is distributed on an "AS IS" BASIS,
//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//    See the License for the specific language governing permissions and
//    limitations under the License.

package utils

import (
	"bytes"
	"encoding/json"
	"io"
	"regexp"
	"strings"

	goyaml "github.com/ghodss/yaml"

	jsonnet "github.com/google/go-jsonnet"
	jsonnetAst "github.com/google/go-jsonnet/ast"
	"k8s.io/apimachinery/pkg/util/yaml"
)

func resolveImage(resolver Resolver, image string) (string, error) {
	n, err := ParseImageName(image)
	if err != nil {
		return "", err
	}

	if err := resolver.Resolve(&n); err != nil {
		return "", err
	}

	return n.String(), nil
}

// RegisterNativeFuncs adds kubecfg's native jsonnet functions to provided VM
func RegisterNativeFuncs(vm *jsonnet.VM, resolver Resolver) {
	// NB: libjsonnet native functions can only pass primitive
	// types, so some functions json-encode the arg.  These
	// "*FromJson" functions will be replaced by regular native
	// version when libjsonnet is able to support this.

	vm.NativeFunction(&jsonnet.NativeFunction{
		Name:   "parseJson",
		Params: []jsonnetAst.Identifier{"json"},
		Func: func(args []interface{}) (res interface{}, err error) {
			data := []byte(args[0].(string))
			err = json.Unmarshal(data, &res)
			return
		},
	})

	vm.NativeFunction(&jsonnet.NativeFunction{
		Name:   "parseYaml",
		Params: []jsonnetAst.Identifier{"yaml"},
		Func: func(args []interface{}) (res interface{}, err error) {
			ret := []interface{}{}
			data := []byte(args[0].(string))
			d := yaml.NewYAMLToJSONDecoder(bytes.NewReader(data))
			for {
				var doc interface{}
				if err := d.Decode(&doc); err != nil {
					if err == io.EOF {
						break
					}
					return nil, err
				}
				ret = append(ret, doc)
			}
			return ret, nil
		},
	})

	vm.NativeFunction(&jsonnet.NativeFunction{
		Name:   "manifestJsonFromJson",
		Params: []jsonnetAst.Identifier{"json", "indent"},
		Func: func(args []interface{}) (res interface{}, err error) {
			data := bytes.TrimSpace([]byte(args[0].(string)))
			indent := int(args[1].(float64))
			buf := bytes.Buffer{}
			if err := json.Indent(&buf, data, "", strings.Repeat(" ", indent)); err != nil {
				return "", err
			}
			buf.WriteString("\n")
			return buf.String(), nil
		},
	})

	vm.NativeFunction(&jsonnet.NativeFunction{
		Name:   "manifestYamlFromJson",
		Params: []jsonnetAst.Identifier{"json"},
		Func: func(args []interface{}) (res interface{}, err error) {
			data := []byte(args[0].(string))
			var input interface{}
			if err := json.Unmarshal(data, &input); err != nil {
				return "", err
			}
			output, err := goyaml.Marshal(input)
			return string(output), err
		},
	})

	vm.NativeFunction(&jsonnet.NativeFunction{
		Name:   "resolveImage",
		Params: []jsonnetAst.Identifier{"image"},
		Func: func(args []interface{}) (res interface{}, err error) {
			return resolveImage(resolver, args[0].(string))
		},
	})

	vm.NativeFunction(&jsonnet.NativeFunction{
		Name:   "escapeStringRegex",
		Params: []jsonnetAst.Identifier{"str"},
		Func: func(args []interface{}) (res interface{}, err error) {
			return regexp.QuoteMeta(args[0].(string)), nil
		},
	})

	vm.NativeFunction(&jsonnet.NativeFunction{
		Name:   "regexMatch",
		Params: []jsonnetAst.Identifier{"regex", "string"},
		Func: func(args []interface{}) (res interface{}, err error) {
			return regexp.MatchString(args[0].(string), args[1].(string))
		},
	})

	vm.NativeFunction(&jsonnet.NativeFunction{
		Name:   "regexSubst",
		Params: []jsonnetAst.Identifier{"regex", "src", "repl"},
		Func: func(args []interface{}) (res interface{}, err error) {
			regex := args[0].(string)
			src := args[1].(string)
			repl := args[2].(string)

			r, err := regexp.Compile(regex)
			if err != nil {
				return "", err
			}
			return r.ReplaceAllString(src, repl), nil
		},
	})
}