Add template function for preferred version

cmd/kops/toolbox_template.go

@@ -32,6 +32,7 @@ import (
 	"k8s.io/kubectl/pkg/util/templates"
 
 	"k8s.io/kops/cmd/kops/util"
+	kopsapi "k8s.io/kops/pkg/apis/kops"
 	"k8s.io/kops/pkg/try"
 	"k8s.io/kops/pkg/util/templater"
 	"k8s.io/kops/upup/pkg/fi/utils"
@@ -68,6 +69,7 @@ type toolboxTemplateOption struct {
 	templatePath  []string
 	values        []string
 	stringValues  []string
+	channel       string
 }
 
 // NewCmdToolboxTemplate returns a new templating command
@@ -96,6 +98,7 @@ func NewCmdToolboxTemplate(f *util.Factory, out io.Writer) *cobra.Command {
 	cmd.Flags().StringArrayVar(&options.stringValues, "set-string", options.stringValues, "Set STRING values on the command line (can specify multiple or separate values with commas: key1=val1,key2=val2)")
 	cmd.Flags().StringSliceVar(&options.templatePath, "template", options.templatePath, "Path to template file or directory of templates to render")
 	cmd.Flags().StringSliceVar(&options.snippetsPath, "snippets", options.snippetsPath, "Path to directory containing snippets used for templating")
+	cmd.Flags().StringVar(&options.channel, "channel", options.channel, "Channel to use for the channel* functions")
 	cmd.Flags().StringVar(&options.outputPath, "output", options.outputPath, "Path to output file, otherwise defaults to stdout")
 	cmd.Flags().StringVar(&options.configValue, "config-value", "", "Show the value of a specific configuration value")
 	cmd.Flags().BoolVar(&options.failOnMissing, "fail-on-missing", true, "Fail on referencing unset variables in templates")
@@ -158,8 +161,18 @@ func runToolBoxTemplate(f *util.Factory, out io.Writer, options *toolboxTemplate
 		}
 	}
 
+	channelLocation := ""
+	if channelLocation == "" {
+		channelLocation = kopsapi.DefaultChannel
+	}
+
+	channel, err := kopsapi.LoadChannel(channelLocation)
+	if err != nil {
+		return fmt.Errorf("error loading channel %q: %v", channelLocation, err)
+	}
+
 	// @step: render each of the templates, splitting on the documents
-	r := templater.NewTemplater()
+	r := templater.NewTemplater(channel)
 	var documents []string
 	for _, x := range templates {
 		content, err := ioutil.ReadFile(x)

docs/cli/kops_toolbox_template.md

@@ -29,6 +29,7 @@ kops toolbox template [flags]
 ### Options
 
 ```
+      --channel string           Channel to use for the channel* functions
       --config-value string      Show the value of a specific configuration value
       --fail-on-missing          Fail on referencing unset variables in templates (default true)
       --format-yaml              Attempt to format the generated yaml content before output

pkg/util/templater/BUILD.bazel

@@ -2,10 +2,17 @@ load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
 
 go_library(
     name = "go_default_library",
-    srcs = ["templater.go"],
+    srcs = [
+        "template_functions.go",
+        "templater.go",
+    ],
     importpath = "k8s.io/kops/pkg/util/templater",
     visibility = ["//visibility:public"],
-    deps = ["//vendor/github.com/Masterminds/sprig/v3:go_default_library"],
+    deps = [
+        "//:go_default_library",
+        "//pkg/apis/kops:go_default_library",
+        "//vendor/github.com/Masterminds/sprig/v3:go_default_library",
+    ],
 )
 
 go_test(
@@ -15,6 +22,7 @@ go_test(
     embed = [":go_default_library"],
     deps = [
         "//pkg/diff:go_default_library",
+        "//tests/integration/channel/simple:go_default_library",
         "//vendor/gopkg.in/yaml.v2:go_default_library",
     ],
 )

pkg/util/templater/template_functions.go

@@ -0,0 +1,48 @@
+/*
+Copyright 2020 The Kubernetes 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 templater
+
+import (
+	"text/template"
+
+	"github.com/Masterminds/sprig/v3"
+	"k8s.io/kops"
+	kopsapi "k8s.io/kops/pkg/apis/kops"
+)
+
+// templateFuncsMap returns a map if the template functions for this template
+func (r *Templater) templateFuncsMap(tm *template.Template) template.FuncMap {
+	// grab the template functions from sprig which are pretty awesome
+	funcs := sprig.TxtFuncMap()
+
+	funcs["indent"] = indentContent
+	// @step: as far as i can see there's no native way in sprig in include external snippets of code
+	funcs["include"] = func(name string, context map[string]interface{}) string {
+		content, err := includeSnippet(tm, name, context)
+		if err != nil {
+			panic(err.Error())
+		}
+
+		return content
+	}
+
+	funcs["ChannelRecommendedKubernetesVersion"] = func() string {
+		return kopsapi.RecommendedKubernetesVersion(r.channel, kops.Version).String()
+	}
+
+	return funcs
+}

pkg/util/templater/templater.go

@@ -22,7 +22,7 @@ import (
 	"strings"
 	"text/template"
 
-	"github.com/Masterminds/sprig/v3"
+	"k8s.io/kops/pkg/apis/kops"
 )
 
 const (
@@ -30,11 +30,15 @@ const (
 )
 
 // Templater is golang template renders
-type Templater struct{}
+type Templater struct {
+	channel *kops.Channel
+}
 
 // NewTemplater returns a new renderer implementation
-func NewTemplater() *Templater {
+func NewTemplater(channel *kops.Channel) *Templater {
-	return &Templater{}
+	return &Templater{
+		channel: channel,
+	}
 }
 
 // Render is responsible for actually rendering the template
@@ -72,25 +76,6 @@ func (r *Templater) Render(content string, context map[string]interface{}, snipp
 	return writer.String(), nil
 }
 
-// templateFuncsMap returns a map if the template functions for this template
-func (r *Templater) templateFuncsMap(tm *template.Template) template.FuncMap {
-	// grab the template functions from sprig which are pretty awesome
-	funcs := sprig.TxtFuncMap()
-
-	funcs["indent"] = indentContent
-	// @step: as far as i can see there's no native way in sprig in include external snippets of code
-	funcs["include"] = func(name string, context map[string]interface{}) string {
-		content, err := includeSnippet(tm, name, context)
-		if err != nil {
-			panic(err.Error())
-		}
-
-		return content
-	}
-
-	return funcs
-}
-
 // indentContent is responsible for indenting the string content
 func indentContent(indent int, content string) string {
 	var b bytes.Buffer

pkg/util/templater/templater_test.go

@@ -21,6 +21,7 @@ import (
 	"testing"
 
 	"k8s.io/kops/pkg/diff"
+	"k8s.io/kops/tests/integration/channel/simple"
 
 	yaml "gopkg.in/yaml.v2"
 )
@@ -81,6 +82,17 @@ func TestRenderIndent(t *testing.T) {
 	makeRenderTests(t, cases)
 }
 
+func TestRenderChannelFunctions(t *testing.T) {
+	cases := []renderTest{
+		{
+			Context:  map[string]interface{}{},
+			Template: `{{ ChannelRecommendedKubernetesVersion }}`,
+			Expected: "1.5.2",
+		},
+	}
+	makeRenderTests(t, cases)
+}
+
 func TestRenderSnippet(t *testing.T) {
 	cases := []renderTest{
 		{
@@ -182,7 +194,11 @@ type renderTest struct {
 }
 
 func makeRenderTests(t *testing.T, tests []renderTest) {
-	r := NewTemplater()
+	channel, err := simple.NewMockChannel()
+	if err != nil {
+		t.Fatalf("could not load channel: %v", err)
+	}
+	r := NewTemplater(channel)
 	for i, x := range tests {
 		render, err := r.Render(x.Template, x.Context, x.Snippets, !x.DisableMissing)
 		if x.NotOK {