⚙️ Add back missing template functions from helm

pkg/api/core/template/functions.go

@@ -0,0 +1,186 @@
+/*
+Copyright The Helm 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 template
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"strings"
+	"text/template"
+
+	"github.com/Masterminds/sprig/v3"
+	"github.com/pelletier/go-toml"
+	"github.com/pkg/errors"
+	"gopkg.in/yaml.v2"
+)
+
+const recursionMaxNums = 1000
+
+// funcMap returns a mapping of all of the functions that Engine has.
+//
+// Because some functions are late-bound (e.g. contain context-sensitive
+// data), the functions may not all perform identically outside of an Engine
+// as they will inside of an Engine.
+//
+// Known late-bound functions:
+//
+//	- "include"
+//	- "tpl"
+//
+// These are late-bound in Engine.Render().  The
+// version included in the FuncMap is a placeholder.
+//
+func funcMap() template.FuncMap {
+	f := sprig.TxtFuncMap()
+
+	// Add some extra functionality
+	extra := template.FuncMap{
+		"toToml":        toTOML,
+		"toYaml":        toYAML,
+		"fromYaml":      fromYAML,
+		"fromYamlArray": fromYAMLArray,
+		"toJson":        toJSON,
+		"fromJson":      fromJSON,
+		"fromJsonArray": fromJSONArray,
+
+		// This is a placeholder for the "include" function, which is
+		// late-bound to a template. By declaring it here, we preserve the
+		// integrity of the linter.
+		"include": func(string, interface{}) string { return "not implemented" },
+	}
+
+	for k, v := range extra {
+		f[k] = v
+	}
+
+	return f
+}
+
+// toYAML takes an interface, marshals it to yaml, and returns a string. It will
+// always return a string, even on marshal error (empty string).
+//
+// This is designed to be called from a template.
+func toYAML(v interface{}) string {
+	data, err := yaml.Marshal(v)
+	if err != nil {
+		// Swallow errors inside of a template.
+		return ""
+	}
+	return strings.TrimSuffix(string(data), "\n")
+}
+
+// fromYAML converts a YAML document into a map[string]interface{}.
+//
+// This is not a general-purpose YAML parser, and will not parse all valid
+// YAML documents. Additionally, because its intended use is within templates
+// it tolerates errors. It will insert the returned error message string into
+// m["Error"] in the returned map.
+func fromYAML(str string) map[string]interface{} {
+	m := map[string]interface{}{}
+
+	if err := yaml.Unmarshal([]byte(str), &m); err != nil {
+		m["Error"] = err.Error()
+	}
+	return m
+}
+
+// fromYAMLArray converts a YAML array into a []interface{}.
+//
+// This is not a general-purpose YAML parser, and will not parse all valid
+// YAML documents. Additionally, because its intended use is within templates
+// it tolerates errors. It will insert the returned error message string as
+// the first and only item in the returned array.
+func fromYAMLArray(str string) []interface{} {
+	a := []interface{}{}
+
+	if err := yaml.Unmarshal([]byte(str), &a); err != nil {
+		a = []interface{}{err.Error()}
+	}
+	return a
+}
+
+// toTOML takes an interface, marshals it to toml, and returns a string. It will
+// always return a string, even on marshal error (empty string).
+//
+// This is designed to be called from a template.
+func toTOML(v interface{}) string {
+	b := bytes.NewBuffer(nil)
+	e := toml.NewEncoder(b)
+	err := e.Encode(v)
+	if err != nil {
+		return err.Error()
+	}
+	return b.String()
+}
+
+// toJSON takes an interface, marshals it to json, and returns a string. It will
+// always return a string, even on marshal error (empty string).
+//
+// This is designed to be called from a template.
+func toJSON(v interface{}) string {
+	data, err := json.Marshal(v)
+	if err != nil {
+		// Swallow errors inside of a template.
+		return ""
+	}
+	return string(data)
+}
+
+// fromJSON converts a JSON document into a map[string]interface{}.
+//
+// This is not a general-purpose JSON parser, and will not parse all valid
+// JSON documents. Additionally, because its intended use is within templates
+// it tolerates errors. It will insert the returned error message string into
+// m["Error"] in the returned map.
+func fromJSON(str string) map[string]interface{} {
+	m := make(map[string]interface{})
+
+	if err := json.Unmarshal([]byte(str), &m); err != nil {
+		m["Error"] = err.Error()
+	}
+	return m
+}
+
+// fromJSONArray converts a JSON array into a []interface{}.
+//
+// This is not a general-purpose JSON parser, and will not parse all valid
+// JSON documents. Additionally, because its intended use is within templates
+// it tolerates errors. It will insert the returned error message string as
+// the first and only item in the returned array.
+func fromJSONArray(str string) []interface{} {
+	a := []interface{}{}
+
+	if err := json.Unmarshal([]byte(str), &a); err != nil {
+		a = []interface{}{err.Error()}
+	}
+	return a
+}
+
+func includeTemplate(tmpl *template.Template, includedNames map[string]int) func(name string, data interface{}) (string, error) {
+	return func(name string, data interface{}) (string, error) {
+		var buf strings.Builder
+		if v, ok := includedNames[name]; ok {
+			if v > recursionMaxNums {
+				return "", errors.Wrapf(fmt.Errorf("unable to execute template"), "rendering template has a nested reference name: %s", name)
+			}
+			includedNames[name]++
+		} else {
+			includedNames[name] = 1
+		}
+		err := tmpl.ExecuteTemplate(&buf, name, data)
+		includedNames[name]--
+		return buf.String(), err
+	}
+}

pkg/api/core/template/string.go

@@ -26,14 +26,23 @@ import (
 	"github.com/pkg/errors"
 	"gopkg.in/yaml.v2"
 
-	"github.com/Masterminds/sprig/v3"
 	"github.com/imdario/mergo"
 )
 
 // String templates a string with the interface
 func String(t string, i interface{}) (string, error) {
 	b := bytes.NewBuffer([]byte{})
-	tmpl, err := template.New("").Funcs(sprig.TxtFuncMap()).Parse(t)
+
+	f := funcMap()
+
+	tmpl := template.New("")
+
+	includedNames := make(map[string]int)
+
+	// Add the 'include' function here so we can close over tmpl.
+	f["include"] = includeTemplate(tmpl, includedNames)
+
+	tmpl, err := tmpl.Funcs(f).Parse(t)
 	if err != nil {
 		return "", err
 	}

pkg/api/core/template/string_test.go

@@ -190,5 +190,33 @@ faa: "baz"
 			Expect(res).To(Equal(""))
 
 		})
+
+		It("correctly parses `include`", func() {
+			testDir, err := ioutil.TempDir(os.TempDir(), "test")
+			Expect(err).ToNot(HaveOccurred())
+			defer os.RemoveAll(testDir)
+
+			toTemplate := filepath.Join(testDir, "totemplate.yaml")
+			values := filepath.Join(testDir, "values.yaml")
+			d := filepath.Join(testDir, "default.yaml")
+
+			writeFile(toTemplate, `
+{{- define "app" -}}
+app_name: {{if .Values.foo}}{{.Values.foo}}{{end}}
+{{- end -}}
+{{ include "app" . | indent 4 }}
+`)
+			writeFile(values, `
+foo: "bar"
+`)
+			writeFile(d, ``)
+
+			Expect(err).ToNot(HaveOccurred())
+
+			res, err := RenderWithValues([]string{toTemplate}, values, d)
+			Expect(err).ToNot(HaveOccurred())
+			Expect(res).To(Equal(`    app_name: bar
+`))
+		})
 	})
 })