add generic json/yaml parsing utilities

Author: mattfenwick

pkg/utils/utils.go

@@ -3,7 +3,11 @@ package utils
 import (
 	"encoding/json"
 	"fmt"
+	"github.com/pkg/errors"
 	log "github.com/sirupsen/logrus"
+	"io/fs"
+	"io/ioutil"
+	"os"
 	"sigs.k8s.io/yaml"
 )
 
@@ -15,16 +19,106 @@ func DoOrDie(err error) {
 
 func JsonString(obj interface{}) string {
 	bytes, err := json.MarshalIndent(obj, "", "  ")
-	DoOrDie(err)
+	DoOrDie(errors.Wrapf(err, "unable to marshal json"))
 	return string(bytes)
 }
 
+func ParseJson[T any](bs []byte) (*T, error) {
+	var t T
+	if err := json.Unmarshal(bs, &t); err != nil {
+		return nil, errors.Wrapf(err, "unable to unmarshal json")
+	}
+	return &t, nil
+}
+
+func ParseJsonFromFile[T any](path string) (*T, error) {
+	bytes, err := ReadFileBytes(path)
+	if err != nil {
+		return nil, err
+	}
+	return ParseJson[T](bytes)
+}
+
+func ParseYaml[T any](bs []byte) (*T, error) {
+	var t T
+	if err := yaml.Unmarshal(bs, &t); err != nil {
+		return nil, errors.Wrapf(err, "unable to unmarshal yaml")
+	}
+	return &t, nil
+}
+
+func ParseYamlStrict[T any](bs []byte) (*T, error) {
+	var t T
+	if err := yaml.UnmarshalStrict(bs, &t); err != nil {
+		return nil, errors.Wrapf(err, "unable to unmarshal yaml")
+	}
+	return &t, nil
+}
+
+func ParseYamlFromFile[T any](path string) (*T, error) {
+	bytes, err := ReadFileBytes(path)
+	if err != nil {
+		return nil, err
+	}
+	return ParseYaml[T](bytes)
+}
+
+func ParseYamlFromFileStrict[T any](path string) (*T, error) {
+	bytes, err := ReadFileBytes(path)
+	if err != nil {
+		return nil, err
+	}
+	return ParseYamlStrict[T](bytes)
+}
+
 func YamlString(obj interface{}) string {
 	bytes, err := yaml.Marshal(obj)
-	DoOrDie(err)
+	DoOrDie(errors.Wrapf(err, "unable to marshal yaml"))
 	return string(bytes)
 }
 
 func PrintJson(obj interface{}) {
 	fmt.Printf("%s\n", JsonString(obj))
 }
+
+func DumpJSON(obj interface{}) string {
+	bytes, err := json.MarshalIndent(obj, "", "  ")
+	DoOrDie(err)
+	return string(bytes)
+}
+
+func WriteJsonToFile(obj interface{}, path string) error {
+	content := DumpJSON(obj)
+	return WriteFile(path, content, 0644)
+}
+
+func PrintJSON(obj interface{}) {
+	fmt.Printf("%s\n", DumpJSON(obj))
+}
+
+func DoesFileExist(path string) bool {
+	if _, err := os.Stat(path); err == nil {
+		return true
+	} else if errors.Is(err, os.ErrNotExist) {
+		return false
+	} else {
+		panic(errors.Wrapf(err, "unable to determine if file %s exists", path))
+	}
+}
+
+// WriteFile wraps calls to ioutil.WriteFile, ensuring that errors are wrapped in a stack trace
+func WriteFile(filename string, contents string, perm fs.FileMode) error {
+	return errors.Wrapf(ioutil.WriteFile(filename, []byte(contents), perm), "unable to write file %s", filename)
+}
+
+// ReadFile wraps calls to ioutil.ReadFile, ensuring that errors are wrapped in a stack trace
+func ReadFile(filename string) (string, error) {
+	bytes, err := ioutil.ReadFile(filename)
+	return string(bytes), errors.Wrapf(err, "unable to read file %s", filename)
+}
+
+// ReadFileBytes wraps calls to ioutil.ReadFile, ensuring that errors are wrapped in a stack trace
+func ReadFileBytes(filename string) ([]byte, error) {
+	bytes, err := ioutil.ReadFile(filename)
+	return bytes, errors.Wrapf(err, "unable to read file %s", filename)
+}