feat: `helmfile template` (#284)

`helmfile template` runs `helm template` over releases within the helmfiles, and provide you a stream of generated yaml documents of Kubernetes resources via stdout.

Resolves #283

helmexec/exec.go

@@ -6,9 +6,10 @@ import (
 	"os"
 	"strings"
 
+	"sync"
+
 	"go.uber.org/zap"
 	"go.uber.org/zap/zapcore"
-	"sync"
 )
 
 const (
@@ -143,6 +144,12 @@ func (helm *execer) DecryptSecret(name string) (string, error) {
 	return tmpFile.Name(), err
 }
 
+func (helm *execer) TemplateRelease(chart string, flags ...string) error {
+	out, err := helm.exec(append([]string{"template", chart}, flags...)...)
+	helm.write(out)
+	return err
+}
+
 func (helm *execer) DiffRelease(name, chart string, flags ...string) error {
 	helm.logger.Infof("Comparing %v %v", name, chart)
 	out, err := helm.exec(append([]string{"diff", "upgrade", "--allow-unreleased", name, chart}, flags...)...)

helmexec/helmexec.go

@@ -10,6 +10,7 @@ type Interface interface {
 	UpdateDeps(chart string) error
 	SyncRelease(name, chart string, flags ...string) error
 	DiffRelease(name, chart string, flags ...string) error
+	TemplateRelease(chart string, flags ...string) error
 	Fetch(chart string, flags ...string) error
 	Lint(chart string, flags ...string) error
 	ReleaseStatus(name string) error

main.go

@@ -11,6 +11,8 @@ import (
 
 	"os/exec"
 
+	"io/ioutil"
+
 	"github.com/roboll/helmfile/args"
 	"github.com/roboll/helmfile/environment"
 	"github.com/roboll/helmfile/helmexec"
@@ -19,7 +21,6 @@ import (
 	"github.com/urfave/cli"
 	"go.uber.org/zap"
 	"go.uber.org/zap/zapcore"
-	"io/ioutil"
 )
 
 const (
@@ -197,6 +198,31 @@ func main() {
 				})
 			},
 		},
+		{
+			Name:  "template",
+			Usage: "template releases from state file against env (helm template)",
+			Flags: []cli.Flag{
+				cli.StringFlag{
+					Name:  "args",
+					Value: "",
+					Usage: "pass args to helm template",
+				},
+				cli.StringSliceFlag{
+					Name:  "values",
+					Usage: "additional value files to be merged into the command",
+				},
+				cli.IntFlag{
+					Name:  "concurrency",
+					Value: 0,
+					Usage: "maximum number of concurrent helm processes to run, 0 is unlimited",
+				},
+			},
+			Action: func(c *cli.Context) error {
+				return findAndIterateOverDesiredStatesUsingFlags(c, func(state *state.HelmState, helm helmexec.Interface) []error {
+					return executeTemplateCommand(c, state, helm)
+				})
+			},
+		},
 		{
 			Name:  "lint",
 			Usage: "lint charts from state file (helm lint)",
@@ -449,6 +475,26 @@ func executeSyncCommand(c *cli.Context, state *state.HelmState, helm helmexec.In
 	return state.SyncReleases(helm, values, workers)
 }
 
+func executeTemplateCommand(c *cli.Context, state *state.HelmState, helm helmexec.Interface) []error {
+	if errs := state.SyncRepos(helm); errs != nil && len(errs) > 0 {
+		return errs
+	}
+
+	if errs := state.UpdateDeps(helm); errs != nil && len(errs) > 0 {
+		return errs
+	}
+
+	if c.GlobalString("helm-binary") != "" {
+		helm.SetHelmBinary(c.GlobalString("helm-binary"))
+	}
+
+	args := args.GetArgs(c.String("args"), state)
+	values := c.StringSlice("values")
+	workers := c.Int("concurrency")
+
+	return state.TemplateReleases(helm, values, workers, args)
+}
+
 func executeDiffCommand(c *cli.Context, state *state.HelmState, helm helmexec.Interface, detailedExitCode, suppressSecrets bool) []error {
 	args := args.GetArgs(c.String("args"), state)
 	if len(args) > 0 {

state/state.go

@@ -3,7 +3,6 @@ package state
 import (
 	"errors"
 	"fmt"
-	"github.com/roboll/helmfile/helmexec"
 	"io/ioutil"
 	"os"
 	"path"
@@ -12,6 +11,8 @@ import (
 	"strings"
 	"sync"
 
+	"github.com/roboll/helmfile/helmexec"
+
 	"regexp"
 
 	"github.com/roboll/helmfile/environment"
@@ -270,6 +271,111 @@ func (state *HelmState) SyncReleases(helm helmexec.Interface, additionalValues [
 	return nil
 }
 
+// TemplateReleases wrapper for executing helm template on the releases
+func (state *HelmState) TemplateReleases(helm helmexec.Interface, additionalValues []string, workerLimit int, args []string) []error {
+	var wgRelease sync.WaitGroup
+	var wgError sync.WaitGroup
+	errs := []error{}
+	jobQueue := make(chan *ReleaseSpec, len(state.Releases))
+	errQueue := make(chan error)
+
+	if workerLimit < 1 {
+		workerLimit = len(state.Releases)
+	}
+
+	wgRelease.Add(len(state.Releases))
+
+	// Create tmp directory and bail immediately if it fails
+	dir, err := ioutil.TempDir("", "")
+	if err != nil {
+		errs = append(errs, err)
+		return errs
+	}
+	defer os.RemoveAll(dir)
+
+	for w := 1; w <= workerLimit; w++ {
+		go func() {
+			for release := range jobQueue {
+				errs := []error{}
+				flags, err := state.flagsForTemplate(helm, release)
+				if err != nil {
+					errs = append(errs, err)
+				}
+				for _, value := range additionalValues {
+					valfile, err := filepath.Abs(value)
+					if err != nil {
+						errs = append(errs, err)
+					}
+
+					if _, err := os.Stat(valfile); os.IsNotExist(err) {
+						errs = append(errs, err)
+					}
+					flags = append(flags, "--values", valfile)
+				}
+
+				chartPath := ""
+				if pathExists(normalizeChart(state.basePath, release.Chart)) {
+					chartPath = normalizeChart(state.basePath, release.Chart)
+				} else {
+					fetchFlags := []string{}
+					if release.Version != "" {
+						chartPath = path.Join(dir, release.Name, release.Version, release.Chart)
+						fetchFlags = append(fetchFlags, "--version", release.Version)
+					} else {
+						chartPath = path.Join(dir, release.Name, "latest", release.Chart)
+					}
+
+					// only fetch chart if it is not already fetched
+					if _, err := os.Stat(chartPath); os.IsNotExist(err) {
+						fetchFlags = append(fetchFlags, "--untar", "--untardir", chartPath)
+						if err := helm.Fetch(release.Chart, fetchFlags...); err != nil {
+							errs = append(errs, err)
+						}
+					}
+					chartPath = path.Join(chartPath, chartNameWithoutRepository(release.Chart))
+				}
+
+				if len(args) > 0 {
+					helm.SetExtraArgs(args...)
+				}
+
+				if len(errs) == 0 {
+					if err := helm.TemplateRelease(chartPath, flags...); err != nil {
+						errs = append(errs, err)
+					}
+				}
+				for _, err := range errs {
+					errQueue <- err
+				}
+				wgRelease.Done()
+			}
+		}()
+	}
+	wgError.Add(1)
+	go func() {
+		for err := range errQueue {
+			errs = append(errs, err)
+		}
+		wgError.Done()
+	}()
+
+	for i := 0; i < len(state.Releases); i++ {
+		jobQueue <- &state.Releases[i]
+	}
+
+	close(jobQueue)
+	wgRelease.Wait()
+
+	close(errQueue)
+	wgError.Wait()
+
+	if len(errs) != 0 {
+		return errs
+	}
+
+	return nil
+}
+
 // DiffReleases wrapper for executing helm diff on the releases
 func (state *HelmState) DiffReleases(helm helmexec.Interface, additionalValues []string, workerLimit int, detailedExitCode, suppressSecrets bool) []error {
 	var wgRelease sync.WaitGroup
@@ -691,6 +797,15 @@ func (state *HelmState) flagsForUpgrade(helm helmexec.Interface, release *Releas
 	return append(flags, common...), nil
 }
 
+func (state *HelmState) flagsForTemplate(helm helmexec.Interface, release *ReleaseSpec) ([]string, error) {
+	flags := []string{}
+	common, err := state.namespaceAndValuesFlags(helm, release)
+	if err != nil {
+		return nil, err
+	}
+	return append(flags, common...), nil
+}
+
 func (state *HelmState) flagsForDiff(helm helmexec.Interface, release *ReleaseSpec) ([]string, error) {
 	flags := []string{}
 	if release.Version != "" {

state/state_test.go

@@ -6,8 +6,9 @@ import (
 	"testing"
 
 	"errors"
-	"github.com/roboll/helmfile/helmexec"
 	"strings"
+
+	"github.com/roboll/helmfile/helmexec"
 )
 
 var logger = helmexec.NewLogger(os.Stdout, "warn")
@@ -537,7 +538,9 @@ func (helm *mockHelmExec) Fetch(chart string, flags ...string) error {
 func (helm *mockHelmExec) Lint(chart string, flags ...string) error {
 	return nil
 }
-
+func (helm *mockHelmExec) TemplateRelease(chart string, flags ...string) error {
+	return nil
+}
 func TestHelmState_SyncRepos(t *testing.T) {
 	tests := []struct {
 		name  string