feat(helm): add a very basic lint command

This adds a lint command that just checks to see if the chart is
parseable and if the templates are paresable.

cmd/helm/lint.go

+package main
+
+import (
+	"fmt"
+
+	"github.com/deis/tiller/pkg/lint"
+	"github.com/spf13/cobra"
+)
+
+var longLintHelp = `
+This command takes a path to a chart and runs a series of tests to verify that
+the chart is well-formed.
+
+If the linter encounters things that will cause the chart to fail installation,
+it will emit [ERROR] messages. If it encounters issues that break with convention
+or recommendation, it will emit [WARNING] messages.
+`
+
+var lintCommand = &cobra.Command{
+	Use:   "lint [flags] PATH",
+	Short: "Examines a chart for possible issues",
+	Long:  longLintHelp,
+	Run:   lintCmd,
+}
+
+func init() {
+	RootCommand.AddCommand(lintCommand)
+}
+
+func lintCmd(cmd *cobra.Command, args []string) {
+	path := "."
+	if len(args) > 0 {
+		path = args[0]
+	}
+	issues := lint.All(path)
+	for _, i := range issues {
+		fmt.Printf("%s\n", i)
+	}
+}

pkg/lint/chartfile.go

+package lint
+
+import (
+	"os"
+	"path/filepath"
+
+	chartutil "github.com/deis/tiller/pkg/chart"
+)
+
+func Chartfile(basepath string) (m []Message) {
+	m = []Message{}
+
+	path := filepath.Join(basepath, "Chart.yaml")
+	if fi, err := os.Stat(path); err != nil {
+		m = append(m, Message{Severity: ErrorSev, Text: "No Chart.yaml file"})
+		return
+	} else if fi.IsDir() {
+		m = append(m, Message{Severity: ErrorSev, Text: "Chart.yaml is a directory."})
+		return
+	}
+
+	cf, err := chartutil.LoadChartfile(path)
+	if err != nil {
+		m = append(m, Message{
+			Severity: ErrorSev,
+			Text:     err.Error(),
+		})
+		return
+	}
+
+	if cf.Name == "" {
+		m = append(m, Message{
+			Severity: ErrorSev,
+			Text:     "Chart.yaml: 'name' is required",
+		})
+	}
+
+	if cf.Version == "" || cf.Version == "0.0.0" {
+		m = append(m, Message{
+			Severity: ErrorSev,
+			Text:     "Chart.yaml: 'version' is required, and must be greater than 0.0.0",
+		})
+	}
+	return
+}

pkg/lint/chartfile_test.go

+package lint
+
+import (
+	"testing"
+)
+
+const badchartfile = "testdata/badchartfile"
+
+func TestChartfile(t *testing.T) {
+	msgs := Chartfile(badchartfile)
+	if len(msgs) != 2 {
+		t.Errorf("Expected 2 errors, got %d", len(msgs))
+	}
+
+	if msgs[0].Text != "Chart.yaml: 'name' is required" {
+		t.Errorf("Unexpected message 0: %s", msgs[0].Text)
+	}
+
+	if msgs[1].Text != "Chart.yaml: 'version' is required, and must be greater than 0.0.0" {
+		t.Errorf("Unexpected message 1: %s", msgs[1].Text)
+	}
+}

pkg/lint/doc.go

+/*Package lint contains tools for linting charts.
+
+Linting is the process of testing charts for errors or warnings regarding
+formatting, compilation, or standards compliance.
+*/
+package lint

pkg/lint/lint.go

+package lint
+
+func All(basedir string) []Message {
+	out := Chartfile(basedir)
+	out = append(out, Templates(basedir)...)
+	return out
+}

pkg/lint/message.go

+package lint
+
+import "fmt"
+
+type Severity int
+
+const (
+	UnknownSev = iota
+	WarningSev
+	ErrorSev
+)
+
+var sev = []string{"INFO", "WARNING", "ERROR"}
+
+type Message struct {
+	// Severity is one of the *Sev constants
+	Severity int
+	// Text contains the message text
+	Text string
+}
+
+// String prints a string representation of this Message.
+//
+// Implements fmt.Stringer.
+func (m Message) String() string {
+	return fmt.Sprintf("[%s] %s", sev[m.Severity], m.Text)
+}

pkg/lint/message_test.go

+package lint
+
+import (
+	"fmt"
+	"testing"
+)
+
+var _ fmt.Stringer = Message{}
+
+func TestMessage(t *testing.T) {
+	m := Message{ErrorSev, "Foo"}
+	if m.String() != "[ERROR] Foo" {
+		t.Errorf("Unexpected output: %s", m.String())
+	}
+
+	m = Message{WarningSev, "Bar"}
+	if m.String() != "[WARNING] Bar" {
+		t.Errorf("Unexpected output: %s", m.String())
+	}
+}

pkg/lint/template.go

+package lint
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"text/template"
+
+	"github.com/Masterminds/sprig"
+)
+
+func Templates(basepath string) (messages []Message) {
+	messages = []Message{}
+	path := filepath.Join(basepath, "templates")
+	if fi, err := os.Stat(path); err != nil {
+		messages = append(messages, Message{Severity: WarningSev, Text: "No templates"})
+		return
+	} else if !fi.IsDir() {
+		messages = append(messages, Message{Severity: ErrorSev, Text: "'templates' is not a directory"})
+		return
+	}
+
+	tpl := template.New("tpl").Funcs(sprig.TxtFuncMap())
+
+	err := filepath.Walk(basepath, func(name string, fi os.FileInfo, e error) error {
+		// If an error is returned, we fail. Non-fatal errors should just be
+		// added directly to messages.
+		if e != nil {
+			return e
+		}
+		if fi.IsDir() {
+			return nil
+		}
+
+		data, err := ioutil.ReadFile(name)
+		if err != nil {
+			messages = append(messages, Message{
+				Severity: ErrorSev,
+				Text:     fmt.Sprintf("cannot read %s: %s", name, err),
+			})
+			return nil
+		}
+
+		// An error rendering a file should emit a warning.
+		newtpl, err := tpl.Parse(string(data))
+		if err != nil {
+			messages = append(messages, Message{
+				Severity: ErrorSev,
+				Text:     fmt.Sprintf("error processing %s: %s", name, err),
+			})
+			return nil
+		}
+		tpl = newtpl
+		return nil
+	})
+
+	if err != nil {
+		messages = append(messages, Message{Severity: ErrorSev, Text: err.Error()})
+	}
+
+	return
+}

pkg/lint/template_test.go

+package lint
+
+import (
+	"strings"
+	"testing"
+)
+
+const templateTestBasedir = "./testdata/albatross"
+
+func TestTemplate(t *testing.T) {
+	res := Templates(templateTestBasedir)
+
+	if len(res) != 1 {
+		t.Fatalf("Expected one error, got %d", len(res))
+	}
+
+	if !strings.Contains(res[0].Text, "deliberateSyntaxError") {
+		t.Errorf("Unexpected error: %s", res[0])
+	}
+}

pkg/lint/testdata/albatross/Chart.yaml

+name: albatross
+description: testing chart
+version: 199.44.12345-Alpha.1+cafe009

pkg/lint/testdata/albatross/templates/albatross.yaml

+metadata:
+  name: {{.name | default "foo" | title}}

pkg/lint/testdata/albatross/templates/fail.yaml

+{{ deliberateSyntaxError }}

pkg/lint/testdata/albatross/values.toml

+name = "mariner"

pkg/lint/testdata/badchartfile/Chart.yaml

+description: A Helm chart for Kubernetes
+version: 0.0.0
+home: ""

pkg/lint/testdata/badchartfile/values.toml

+# Default values for badchartfile.
+# This is a TOML-formatted file. https://github.com/toml-lang/toml
+# Declare name/value pairs to be passed into your templates.
+# name = "value"