feat: helmfile as a go library (#639)

* feat: helmfile as a go library

This removes almost all the dependencies from the helmfile core logic to urfave/cli. `main.go` is now a thin wrapper around the core logic implemented in `pkg/app`.

cmd/cmd.go

@@ -1,98 +0,0 @@
-package cmd
-
-import (
-	"fmt"
-	"github.com/roboll/helmfile/pkg/app"
-	"github.com/roboll/helmfile/pkg/helmexec"
-	"github.com/roboll/helmfile/pkg/state"
-	"github.com/urfave/cli"
-	"go.uber.org/zap"
-	"strings"
-)
-
-func VisitAllDesiredStates(c *cli.Context, converge func(*state.HelmState, helmexec.Interface, app.Context) (bool, []error)) error {
-	a, fileOrDir, err := InitAppEntry(c, false)
-	if err != nil {
-		return err
-	}
-
-	ctx := app.NewContext()
-
-	convergeWithHelmBinary := func(st *state.HelmState, helm helmexec.Interface) (bool, []error) {
-		if c.GlobalString("helm-binary") != "" {
-			helm.SetHelmBinary(c.GlobalString("helm-binary"))
-		}
-		return converge(st, helm, ctx)
-	}
-
-	err = a.VisitDesiredStates(fileOrDir, app.LoadOpts{Selectors: a.Selectors}, convergeWithHelmBinary)
-
-	return toCliError(c, err)
-}
-
-func InitAppEntry(c *cli.Context, reverse bool) (*app.App, string, error) {
-	if c.NArg() > 0 {
-		cli.ShowAppHelp(c)
-		return nil, "", fmt.Errorf("err: extraneous arguments: %s", strings.Join(c.Args(), ", "))
-	}
-
-	fileOrDir := c.GlobalString("file")
-	kubeContext := c.GlobalString("kube-context")
-	namespace := c.GlobalString("namespace")
-	selectors := c.GlobalStringSlice("selector")
-	logger := c.App.Metadata["logger"].(*zap.SugaredLogger)
-
-	env := c.GlobalString("environment")
-	if env == "" {
-		env = state.DefaultEnv
-	}
-
-	app := app.Init(&app.App{
-		KubeContext: kubeContext,
-		Logger:      logger,
-		Reverse:     reverse,
-		Env:         env,
-		Namespace:   namespace,
-		Selectors:   selectors,
-	})
-
-	return app, fileOrDir, nil
-}
-
-func FindAndIterateOverDesiredStatesUsingFlagsWithReverse(c *cli.Context, reverse bool, converge func(*state.HelmState, helmexec.Interface, app.Context) []error) error {
-	a, fileOrDir, err := InitAppEntry(c, reverse)
-	if err != nil {
-		return err
-	}
-
-	ctx := app.NewContext()
-
-	convergeWithHelmBinary := func(st *state.HelmState, helm helmexec.Interface) []error {
-		if c.GlobalString("helm-binary") != "" {
-			helm.SetHelmBinary(c.GlobalString("helm-binary"))
-		}
-		return converge(st, helm, ctx)
-	}
-
-	err = a.VisitDesiredStatesWithReleasesFiltered(fileOrDir, convergeWithHelmBinary)
-
-	return toCliError(c, err)
-}
-
-func toCliError(c *cli.Context, err error) error {
-	if err != nil {
-		switch e := err.(type) {
-		case *app.NoMatchingHelmfileError:
-			noMatchingExitCode := 3
-			if c.GlobalBool("allow-no-matching-release") {
-				noMatchingExitCode = 0
-			}
-			return cli.NewExitError(e.Error(), noMatchingExitCode)
-		case *app.Error:
-			return cli.NewExitError(e.Error(), e.Code())
-		default:
-			panic(fmt.Errorf("BUG: please file an github issue for this unhandled error: %T: %v", e, e))
-		}
-	}
-	return err
-}

cmd/deps.go

@@ -1,37 +0,0 @@
-package cmd
-
-import (
-	"github.com/roboll/helmfile/pkg/app"
-	"github.com/roboll/helmfile/pkg/argparser"
-	"github.com/roboll/helmfile/pkg/helmexec"
-	"github.com/roboll/helmfile/pkg/state"
-	"github.com/urfave/cli"
-)
-
-func Deps() cli.Command {
-	return cli.Command{
-		Name:  "deps",
-		Usage: "update charts based on the contents of requirements.yaml",
-		Flags: []cli.Flag{
-			cli.StringFlag{
-				Name:  "args",
-				Value: "",
-				Usage: "pass args to helm exec",
-			},
-		},
-		Action: func(c *cli.Context) error {
-			return VisitAllDesiredStates(c, func(state *state.HelmState, helm helmexec.Interface, ctx app.Context) (bool, []error) {
-				args := argparser.GetArgs(c.String("args"), state)
-				if len(args) > 0 {
-					helm.SetExtraArgs(args...)
-				}
-
-				errs := state.UpdateDeps(helm)
-
-				ok := len(errs) == 0
-
-				return ok, errs
-			})
-		},
-	}
-}

main.go

@@ -2,9 +2,7 @@ package main
 
 import (
 	"fmt"
-	"github.com/roboll/helmfile/cmd"
 	"github.com/roboll/helmfile/pkg/app"
-	"github.com/roboll/helmfile/pkg/argparser"
 	"github.com/roboll/helmfile/pkg/helmexec"
 	"github.com/roboll/helmfile/pkg/state"
 	"github.com/urfave/cli"
@@ -94,7 +92,20 @@ func main() {
 
 	cliApp.Before = configureLogging
 	cliApp.Commands = []cli.Command{
-		cmd.Deps(),
+		{
+			Name:  "deps",
+			Usage: "update charts based on the contents of requirements.yaml",
+			Flags: []cli.Flag{
+				cli.StringFlag{
+					Name:  "args",
+					Value: "",
+					Usage: "pass args to helm exec",
+				},
+			},
+			Action: action(func(run *app.App, c configImpl) error {
+				return run.Deps(c)
+			}),
+		},
 		{
 			Name:  "repos",
 			Usage: "sync repositories from state file (helm repo add && helm repo update)",
@@ -105,20 +116,9 @@ func main() {
 					Usage: "pass args to helm exec",
 				},
 			},
-			Action: func(c *cli.Context) error {
+			Action: action(func(run *app.App, c configImpl) error {
-				return cmd.VisitAllDesiredStates(c, func(state *state.HelmState, helm helmexec.Interface, ctx app.Context) (bool, []error) {
+				return run.Repos(c)
-					args := argparser.GetArgs(c.String("args"), state)
+			}),
-					if len(args) > 0 {
-						helm.SetExtraArgs(args...)
-					}
-
-					errs := ctx.SyncReposOnce(state, helm)
-
-					ok := len(state.Repositories) > 0 && len(errs) == 0
-
-					return ok, errs
-				})
-			},
 		},
 		{
 			Name:  "charts",
@@ -139,14 +139,9 @@ func main() {
 					Usage: "maximum number of concurrent helm processes to run, 0 is unlimited",
 				},
 			},
-			Action: func(c *cli.Context) error {
+			Action: action(func(run *app.App, c configImpl) error {
-				affectedReleases := state.AffectedReleases{}
+				return run.DeprecatedSyncCharts(c)
-				errs := findAndIterateOverDesiredStatesUsingFlags(c, func(st *state.HelmState, helm helmexec.Interface, _ app.Context) []error {
+			}),
-					return executeSyncCommand(c, &affectedReleases, st, helm)
-				})
-				affectedReleases.DisplayAffectedReleases(c.App.Metadata["logger"].(*zap.SugaredLogger))
-				return errs
-			},
 		},
 		{
 			Name:  "diff",
@@ -179,24 +174,9 @@ func main() {
 					Usage: "maximum number of concurrent helm processes to run, 0 is unlimited",
 				},
 			},
-			Action: func(c *cli.Context) error {
+			Action: action(func(run *app.App, c configImpl) error {
-				return findAndIterateOverDesiredStatesUsingFlags(c, func(state *state.HelmState, helm helmexec.Interface, ctx app.Context) []error {
+				return run.Diff(c)
-					if !c.Bool("skip-deps") {
+			}),
-						if errs := ctx.SyncReposOnce(state, helm); errs != nil && len(errs) > 0 {
-							return errs
-						}
-						if errs := state.BuildDeps(helm); errs != nil && len(errs) > 0 {
-							return errs
-						}
-					}
-					if errs := state.PrepareReleases(helm, "diff"); errs != nil && len(errs) > 0 {
-						return errs
-					}
-
-					_, errs := ExecuteDiffCommand(NewUrfaveCliConfigImpl(c), state, helm, c.Bool("detailed-exitcode"), c.Bool("suppress-secrets"))
-					return errs
-				})
-			},
 		},
 		{
 			Name:  "template",
@@ -221,22 +201,9 @@ func main() {
 					Usage: "skip running `helm repo update` and `helm dependency build`",
 				},
 			},
-			Action: func(c *cli.Context) error {
+			Action: action(func(run *app.App, c configImpl) error {
-				return findAndIterateOverDesiredStatesUsingFlags(c, func(state *state.HelmState, helm helmexec.Interface, ctx app.Context) []error {
+				return run.Template(c)
-					if !c.Bool("skip-deps") {
+			}),
-						if errs := ctx.SyncReposOnce(state, helm); errs != nil && len(errs) > 0 {
-							return errs
-						}
-						if errs := state.BuildDeps(helm); errs != nil && len(errs) > 0 {
-							return errs
-						}
-					}
-					if errs := state.PrepareReleases(helm, "template"); errs != nil && len(errs) > 0 {
-						return errs
-					}
-					return executeTemplateCommand(c, state, helm)
-				})
-			},
 		},
 		{
 			Name:  "lint",
@@ -261,25 +228,9 @@ func main() {
 					Usage: "skip running `helm repo update` and `helm dependency build`",
 				},
 			},
-			Action: func(c *cli.Context) error {
+			Action: action(func(run *app.App, c configImpl) error {
-				return findAndIterateOverDesiredStatesUsingFlags(c, func(state *state.HelmState, helm helmexec.Interface, ctx app.Context) []error {
+				return run.Lint(c)
-					values := c.StringSlice("values")
+			}),
-					args := argparser.GetArgs(c.String("args"), state)
-					workers := c.Int("concurrency")
-					if !c.Bool("skip-deps") {
-						if errs := ctx.SyncReposOnce(state, helm); errs != nil && len(errs) > 0 {
-							return errs
-						}
-						if errs := state.BuildDeps(helm); errs != nil && len(errs) > 0 {
-							return errs
-						}
-					}
-					if errs := state.PrepareReleases(helm, "lint"); errs != nil && len(errs) > 0 {
-						return errs
-					}
-					return state.LintReleases(helm, values, args, workers)
-				})
-			},
 		},
 		{
 			Name:  "sync",
@@ -304,25 +255,9 @@ func main() {
 					Usage: "skip running `helm repo update` and `helm dependency build`",
 				},
 			},
-			Action: func(c *cli.Context) error {
+			Action: action(func(run *app.App, c configImpl) error {
-				affectedReleases := state.AffectedReleases{}
+				return run.Sync(c)
-				errs := findAndIterateOverDesiredStatesUsingFlags(c, func(st *state.HelmState, helm helmexec.Interface, ctx app.Context) []error {
+			}),
-					if !c.Bool("skip-deps") {
-						if errs := ctx.SyncReposOnce(st, helm); errs != nil && len(errs) > 0 {
-							return errs
-						}
-						if errs := st.BuildDeps(helm); errs != nil && len(errs) > 0 {
-							return errs
-						}
-					}
-					if errs := st.PrepareReleases(helm, "sync"); errs != nil && len(errs) > 0 {
-						return errs
-					}
-					return executeSyncCommand(c, &affectedReleases, st, helm)
-				})
-				affectedReleases.DisplayAffectedReleases(c.App.Metadata["logger"].(*zap.SugaredLogger))
-				return errs
-			},
 		},
 		{
 			Name:  "apply",
@@ -351,88 +286,9 @@ func main() {
 					Usage: "skip running `helm repo update` and `helm dependency build`",
 				},
 			},
-			Action: func(c *cli.Context) error {
+			Action: action(func(run *app.App, c configImpl) error {
-				affectedReleases := state.AffectedReleases{}
+				return run.Apply(c)
-				errs := findAndIterateOverDesiredStatesUsingFlags(c, func(st *state.HelmState, helm helmexec.Interface, ctx app.Context) []error {
+			}),
-					if !c.Bool("skip-deps") {
-						if errs := ctx.SyncReposOnce(st, helm); errs != nil && len(errs) > 0 {
-							return errs
-						}
-						if errs := st.BuildDeps(helm); errs != nil && len(errs) > 0 {
-							return errs
-						}
-					}
-					if errs := st.PrepareReleases(helm, "apply"); errs != nil && len(errs) > 0 {
-						return errs
-					}
-
-					releases, errs := ExecuteDiffCommand(NewUrfaveCliConfigImpl(c), st, helm, true, c.Bool("suppress-secrets"))
-
-					releasesToBeDeleted, err := st.DetectReleasesToBeDeleted(helm)
-					if err != nil {
-						errs = append(errs, err)
-					}
-
-					fatalErrs := []error{}
-
-					noError := true
-					for _, e := range errs {
-						switch err := e.(type) {
-						case *state.ReleaseError:
-							if err.Code != 2 {
-								noError = false
-								fatalErrs = append(fatalErrs, e)
-							}
-						default:
-							noError = false
-							fatalErrs = append(fatalErrs, e)
-						}
-					}
-
-					// sync only when there are changes
-					if noError {
-						if len(releases) == 0 && len(releasesToBeDeleted) == 0 {
-							// TODO better way to get the logger
-							logger := c.App.Metadata["logger"].(*zap.SugaredLogger)
-							logger.Infof("")
-							logger.Infof("No affected releases")
-						} else {
-							names := []string{}
-							for _, r := range releases {
-								names = append(names, fmt.Sprintf("  %s (%s) UPDATED", r.Name, r.Chart))
-							}
-							for _, r := range releasesToBeDeleted {
-								names = append(names, fmt.Sprintf("  %s (%s) DELETED", r.Name, r.Chart))
-							}
-
-							msg := fmt.Sprintf(`Affected releases are:
-%s
-
-Do you really want to apply?
-  Helmfile will apply all your changes, as shown above.
-
-`, strings.Join(names, "\n"))
-							interactive := c.GlobalBool("interactive")
-							if !interactive || interactive && askForConfirmation(msg) {
-								rs := []state.ReleaseSpec{}
-								for _, r := range releases {
-									rs = append(rs, *r)
-								}
-								for _, r := range releasesToBeDeleted {
-									rs = append(rs, *r)
-								}
-
-								st.Releases = rs
-								return executeSyncCommand(c, &affectedReleases, st, helm)
-							}
-						}
-					}
-
-					return fatalErrs
-				})
-				affectedReleases.DisplayAffectedReleases(c.App.Metadata["logger"].(*zap.SugaredLogger))
-				return errs
-			},
 		},
 		{
 			Name:  "status",
@@ -449,18 +305,9 @@ Do you really want to apply?
 					Usage: "pass args to helm exec",
 				},
 			},
-			Action: func(c *cli.Context) error {
+			Action: action(func(run *app.App, c configImpl) error {
-				return findAndIterateOverDesiredStatesUsingFlags(c, func(state *state.HelmState, helm helmexec.Interface, _ app.Context) []error {
+				return run.Status(c)
-					workers := c.Int("concurrency")
+			}),
-
-					args := argparser.GetArgs(c.String("args"), state)
-					if len(args) > 0 {
-						helm.SetExtraArgs(args...)
-					}
-
-					return state.ReleaseStatuses(helm, workers)
-				})
-			},
 		},
 		{
 			Name:  "delete",
@@ -476,37 +323,9 @@ Do you really want to apply?
 					Usage: "purge releases i.e. free release names and histories",
 				},
 			},
-			Action: func(c *cli.Context) error {
+			Action: action(func(run *app.App, c configImpl) error {
-				affectedReleases := state.AffectedReleases{}
+				return run.Delete(c)
-				errs := cmd.FindAndIterateOverDesiredStatesUsingFlagsWithReverse(c, true, func(state *state.HelmState, helm helmexec.Interface, _ app.Context) []error {
+			}),
-					purge := c.Bool("purge")
-
-					args := argparser.GetArgs(c.String("args"), state)
-					if len(args) > 0 {
-						helm.SetExtraArgs(args...)
-					}
-
-					names := make([]string, len(state.Releases))
-					for i, r := range state.Releases {
-						names[i] = fmt.Sprintf("  %s (%s)", r.Name, r.Chart)
-					}
-
-					msg := fmt.Sprintf(`Affected releases are:
-%s
-
-Do you really want to delete?
-  Helmfile will delete all your releases, as shown above.
-
-`, strings.Join(names, "\n"))
-					interactive := c.GlobalBool("interactive")
-					if !interactive || interactive && askForConfirmation(msg) {
-						return state.DeleteReleases(&affectedReleases, helm, purge)
-					}
-					return nil
-				})
-				affectedReleases.DisplayAffectedReleases(c.App.Metadata["logger"].(*zap.SugaredLogger))
-				return errs
-			},
 		},
 		{
 			Name:  "destroy",
@@ -518,35 +337,9 @@ Do you really want to delete?
 					Usage: "pass args to helm exec",
 				},
 			},
-			Action: func(c *cli.Context) error {
+			Action: action(func(run *app.App, c configImpl) error {
-				affectedReleases := state.AffectedReleases{}
+				return run.Destroy(c)
-				errs := cmd.FindAndIterateOverDesiredStatesUsingFlagsWithReverse(c, true, func(state *state.HelmState, helm helmexec.Interface, _ app.Context) []error {
+			}),
-					args := argparser.GetArgs(c.String("args"), state)
-					if len(args) > 0 {
-						helm.SetExtraArgs(args...)
-					}
-
-					names := make([]string, len(state.Releases))
-					for i, r := range state.Releases {
-						names[i] = fmt.Sprintf("  %s (%s)", r.Name, r.Chart)
-					}
-
-					msg := fmt.Sprintf(`Affected releases are:
-%s
-
-Do you really want to delete?
-  Helmfile will delete all your releases, as shown above.
-
-`, strings.Join(names, "\n"))
-					interactive := c.GlobalBool("interactive")
-					if !interactive || interactive && askForConfirmation(msg) {
-						return state.DeleteReleases(&affectedReleases, helm, true)
-					}
-					return nil
-				})
-				affectedReleases.DisplayAffectedReleases(c.App.Metadata["logger"].(*zap.SugaredLogger))
-				return errs
-			},
 		},
 		{
 			Name:  "test",
@@ -572,20 +365,9 @@ Do you really want to delete?
 					Usage: "maximum number of concurrent helm processes to run, 0 is unlimited",
 				},
 			},
-			Action: func(c *cli.Context) error {
+			Action: action(func(run *app.App, c configImpl) error {
-				return findAndIterateOverDesiredStatesUsingFlags(c, func(state *state.HelmState, helm helmexec.Interface, _ app.Context) []error {
+				return run.Test(c)
-					cleanup := c.Bool("cleanup")
+			}),
-					timeout := c.Int("timeout")
-					concurrency := c.Int("concurrency")
-
-					args := argparser.GetArgs(c.String("args"), state)
-					if len(args) > 0 {
-						helm.SetExtraArgs(args...)
-					}
-
-					return state.TestReleases(helm, cleanup, timeout, concurrency)
-				})
-			},
 		},
 	}
 
@@ -596,41 +378,19 @@ Do you really want to delete?
 	}
 }
 
-func executeSyncCommand(c *cli.Context, affectedReleases *state.AffectedReleases, state *state.HelmState, helm helmexec.Interface) []error {
-	args := argparser.GetArgs(c.String("args"), state)
-	if len(args) > 0 {
-		helm.SetExtraArgs(args...)
-	}
-
-	values := c.StringSlice("values")
-	workers := c.Int("concurrency")
-
-	return state.SyncReleases(affectedReleases, helm, values, workers)
-}
-
-func executeTemplateCommand(c *cli.Context, state *state.HelmState, helm helmexec.Interface) []error {
-	args := argparser.GetArgs(c.String("args"), state)
-	values := c.StringSlice("values")
-	workers := c.Int("concurrency")
-
-	return state.TemplateReleases(helm, values, args, workers)
-}
-
-type Config interface {
-	HasCommandName(string) bool
-	Values() []string
-	Concurrency() int
-	Args() string
-}
-
 type configImpl struct {
 	c *cli.Context
 }
 
-func NewUrfaveCliConfigImpl(c *cli.Context) configImpl {
+func NewUrfaveCliConfigImpl(c *cli.Context) (configImpl, error) {
+	if c.NArg() > 0 {
+		cli.ShowAppHelp(c)
+		return configImpl{}, fmt.Errorf("err: extraneous arguments: %s", strings.Join(c.Args(), ", "))
+	}
+
 	return configImpl{
 		c: c,
-	}
+	}, nil
 }
 
 func (c configImpl) Values() []string {
@@ -649,17 +409,105 @@ func (c configImpl) HasCommandName(name string) bool {
 	return c.c.Command.HasName(name)
 }
 
-func ExecuteDiffCommand(c Config, st *state.HelmState, helm helmexec.Interface, detailedExitCode, suppressSecrets bool) ([]*state.ReleaseSpec, []error) {
+// DiffConfig
-	args := argparser.GetArgs(c.Args(), st)
+
-	if len(args) > 0 {
+func (c configImpl) SkipDeps() bool {
-		helm.SetExtraArgs(args...)
+	return c.c.Bool("skip-deps")
+}
+
+func (c configImpl) DetailedExitcode() bool {
+	return c.c.Bool("detailed-exitcode")
+}
+
+func (c configImpl) SuppressSecrets() bool {
+	return c.c.Bool("suppress-secrets")
+}
+
+// DeleteConfig
+
+func (c configImpl) Purge() bool {
+	return c.c.Bool("purge")
+}
+
+// TestConfig
+
+func (c configImpl) Cleanup() bool {
+	return c.c.Bool("cleanup")
+}
+
+func (c configImpl) Timeout() int {
+	return c.c.Int("timeout")
+}
+
+// GlobalConfig
+
+func (c configImpl) HelmBinary() string {
+	return c.c.GlobalString("helm-binary")
+}
+
+func (c configImpl) KubeContext() string {
+	return c.c.GlobalString("kube-context")
+}
+
+func (c configImpl) Namespace() string {
+	return c.c.GlobalString("namespace")
+}
+
+func (c configImpl) FileOrDir() string {
+	return c.c.GlobalString("file")
+}
+
+func (c configImpl) Selectors() []string {
+	return c.c.GlobalStringSlice("selector")
+}
+
+func (c configImpl) Interactive() bool {
+	return c.c.GlobalBool("interactive")
+}
+
+func (c configImpl) Logger() *zap.SugaredLogger {
+	return c.c.App.Metadata["logger"].(*zap.SugaredLogger)
+}
+
+func (c configImpl) Env() string {
+	env := c.c.GlobalString("environment")
+	if env == "" {
+		env = state.DefaultEnv
 	}
-
+	return env
-	triggerCleanupEvents := c.HasCommandName("diff")
-
-	return st.DiffReleases(helm, c.Values(), c.Concurrency(), detailedExitCode, suppressSecrets, triggerCleanupEvents)
 }
 
-func findAndIterateOverDesiredStatesUsingFlags(c *cli.Context, converge func(*state.HelmState, helmexec.Interface, app.Context) []error) error {
+func action(do func(*app.App, configImpl) error) func(*cli.Context) error {
-	return cmd.FindAndIterateOverDesiredStatesUsingFlagsWithReverse(c, false, converge)
+	return func(implCtx *cli.Context) error {
+		conf, err := NewUrfaveCliConfigImpl(implCtx)
+		if err != nil {
+			return err
+		}
+
+		a := app.New(conf)
+
+		a.ErrorHandler = func(err error) error {
+			return toCliError(implCtx, err)
+		}
+
+		return do(a, conf)
+	}
+}
+
+func toCliError(c *cli.Context, err error) error {
+	if err != nil {
+		switch e := err.(type) {
+		case *app.NoMatchingHelmfileError:
+			noMatchingExitCode := 3
+			if c.GlobalBool("allow-no-matching-release") {
+				noMatchingExitCode = 0
+			}
+			return cli.NewExitError(e.Error(), noMatchingExitCode)
+		case *app.Error:
+			return cli.NewExitError(e.Error(), e.Code())
+		default:
+			panic(fmt.Errorf("BUG: please file an github issue for this unhandled error: %T: %v", e, e))
+		}
+	}
+	return err
 }

pkg/app/app.go

@@ -24,6 +24,12 @@ type App struct {
 	Env         string
 	Namespace   string
 	Selectors   []string
+	HelmBinary  string
+	Args        string
+
+	FileOrDir string
+
+	ErrorHandler func(error) error
 
 	readFile          func(string) ([]byte, error)
 	fileExists        func(string) (bool, error)
@@ -36,6 +42,19 @@ type App struct {
 	chdir func(string) error
 }
 
+func New(conf ConfigProvider) *App {
+	return Init(&App{
+		KubeContext: conf.KubeContext(),
+		Logger:      conf.Logger(),
+		Env:         conf.Env(),
+		Namespace:   conf.Namespace(),
+		Selectors:   conf.Selectors(),
+		HelmBinary:  conf.HelmBinary(),
+		Args:        conf.Args(),
+		FileOrDir:   conf.FileOrDir(),
+	})
+}
+
 func Init(app *App) *App {
 	app.readFile = ioutil.ReadFile
 	app.glob = filepath.Glob
@@ -48,6 +67,84 @@ func Init(app *App) *App {
 	return app
 }
 
+func (a *App) Deps(c DepsConfigProvider) error {
+	return a.ForEachState(func(run *Run) []error {
+		return run.Deps(c)
+	})
+}
+
+func (a *App) Repos(c ReposConfigProvider) error {
+	return a.ForEachState(func(run *Run) []error {
+		return run.Repos(c)
+	})
+}
+
+func (a *App) reverse() *App {
+	new := *a
+	new.Reverse = true
+	return &new
+}
+
+func (a *App) DeprecatedSyncCharts(c DeprecatedChartsConfigProvider) error {
+	return a.ForEachState(func(run *Run) []error {
+		return run.DeprecatedSyncCharts(c)
+	})
+}
+
+func (a *App) Diff(c DiffConfigProvider) error {
+	return a.ForEachState(func(run *Run) []error {
+		return run.Diff(c)
+	})
+}
+
+func (a *App) Template(c TemplateConfigProvider) error {
+	return a.ForEachState(func(run *Run) []error {
+		return run.Template(c)
+	})
+}
+
+func (a *App) Lint(c LintConfigProvider) error {
+	return a.ForEachState(func(run *Run) []error {
+		return run.Lint(c)
+	})
+}
+
+func (a *App) Sync(c SyncConfigProvider) error {
+	return a.ForEachState(func(run *Run) []error {
+		return run.Sync(c)
+	})
+}
+
+func (a *App) Apply(c ApplyConfigProvider) error {
+	return a.ForEachState(func(run *Run) []error {
+		return run.Apply(c)
+	})
+}
+
+func (a *App) Status(c StatusesConfigProvider) error {
+	return a.ForEachState(func(run *Run) []error {
+		return run.Status(c)
+	})
+}
+
+func (a *App) Delete(c DeleteConfigProvider) error {
+	return a.reverse().ForEachState(func(run *Run) []error {
+		return run.Delete(c)
+	})
+}
+
+func (a *App) Destroy(c DestroyConfigProvider) error {
+	return a.reverse().ForEachState(func(run *Run) []error {
+		return run.Destroy(c)
+	})
+}
+
+func (a *App) Test(c TestConfigProvider) error {
+	return a.ForEachState(func(run *Run) []error {
+		return run.Test(c)
+	})
+}
+
 func (a *App) within(dir string, do func() error) error {
 	if dir == "." {
 		return do()
@@ -140,7 +237,7 @@ func (a *App) loadDesiredStateFromYaml(file string, opts ...LoadOpts) (*state.He
 	return ld.Load(file, op)
 }
 
-func (a *App) VisitDesiredStates(fileOrDir string, opts LoadOpts, converge func(*state.HelmState, helmexec.Interface) (bool, []error)) error {
+func (a *App) visitStates(fileOrDir string, opts LoadOpts, converge func(*state.HelmState, helmexec.Interface) (bool, []error)) error {
 	noMatchInHelmfiles := true
 
 	err := a.visitStateFiles(fileOrDir, func(f, d string) error {
@@ -195,7 +292,7 @@ func (a *App) VisitDesiredStates(fileOrDir string, opts LoadOpts, converge func(
 				} else {
 					optsForNestedState.Selectors = m.Selectors
 				}
-				if err := a.VisitDesiredStates(m.Path, optsForNestedState, converge); err != nil {
+				if err := a.visitStates(m.Path, optsForNestedState, converge); err != nil {
 					switch err.(type) {
 					case *NoMatchingHelmfileError:
 
@@ -229,10 +326,26 @@ func (a *App) VisitDesiredStates(fileOrDir string, opts LoadOpts, converge func(
 	return nil
 }
 
+func (a *App) ForEachState(do func(*Run) []error) error {
+	err := a.VisitDesiredStatesWithReleasesFiltered(a.FileOrDir, func(st *state.HelmState, helm helmexec.Interface) []error {
+		ctx := NewContext()
+
+		run := NewRun(st, helm, ctx)
+
+		return do(run)
+	})
+
+	if err != nil && a.ErrorHandler != nil {
+		return a.ErrorHandler(err)
+	}
+
+	return err
+}
+
 func (a *App) VisitDesiredStatesWithReleasesFiltered(fileOrDir string, converge func(*state.HelmState, helmexec.Interface) []error) error {
 	opts := LoadOpts{Selectors: a.Selectors}
 
-	err := a.VisitDesiredStates(fileOrDir, opts, func(st *state.HelmState, helm helmexec.Interface) (bool, []error) {
+	err := a.visitStates(fileOrDir, opts, func(st *state.HelmState, helm helmexec.Interface) (bool, []error) {
 		if len(st.Selectors) > 0 {
 			err := st.FilterReleases()
 			if err != nil {
@@ -240,6 +353,10 @@ func (a *App) VisitDesiredStatesWithReleasesFiltered(fileOrDir string, converge
 			}
 		}
 
+		if a.HelmBinary != "" {
+			helm.SetHelmBinary(a.HelmBinary)
+		}
+
 		type Key struct {
 			TillerNamespace, Name string
 		}

pkg/app/ask.go

@@ -1,4 +1,4 @@
-package main
+package app
 
 import (
 	"bufio"
@@ -11,7 +11,7 @@ import (
 // Copyright (c) 2017 Roland Singer [roland.singer@desertbit.com]
 //
 // Shamelessly borrowed from @r0l1's awesome work that is available at https://gist.github.com/r0l1/3dcbb0c8f6cfe9c66ab8008f55f8f28b
-func askForConfirmation(s string) bool {
+func AskForConfirmation(s string) bool {
 	reader := bufio.NewReader(os.Stdin)
 
 	for {

pkg/app/config.go

@@ -0,0 +1,128 @@
+package app
+
+import "go.uber.org/zap"
+
+type ConfigProvider interface {
+	Args() string
+	HelmBinary() string
+
+	FileOrDir() string
+	KubeContext() string
+	Namespace() string
+	Selectors() []string
+	Env() string
+
+	loggingConfig
+}
+
+type DeprecatedChartsConfigProvider interface {
+	Values() []string
+
+	concurrencyConfig
+	loggingConfig
+}
+
+type DepsConfigProvider interface {
+	Args() string
+}
+
+type ReposConfigProvider interface {
+	Args() string
+}
+
+type ApplyConfigProvider interface {
+	Args() string
+
+	Values() []string
+	SkipDeps() bool
+
+	SuppressSecrets() bool
+
+	concurrencyConfig
+	interactive
+	loggingConfig
+}
+
+type SyncConfigProvider interface {
+	Args() string
+
+	Values() []string
+	SkipDeps() bool
+
+	concurrencyConfig
+	loggingConfig
+}
+
+type DiffConfigProvider interface {
+	Args() string
+
+	Values() []string
+	SkipDeps() bool
+
+	SuppressSecrets() bool
+
+	DetailedExitcode() bool
+
+	concurrencyConfig
+}
+
+type DeleteConfigProvider interface {
+	Args() string
+
+	Purge() bool
+
+	interactive
+	loggingConfig
+}
+
+type DestroyConfigProvider interface {
+	Args() string
+
+	interactive
+	loggingConfig
+}
+
+type TestConfigProvider interface {
+	Args() string
+
+	Timeout() int
+	Cleanup() bool
+
+	concurrencyConfig
+}
+
+type LintConfigProvider interface {
+	Args() string
+
+	Values() []string
+	SkipDeps() bool
+
+	concurrencyConfig
+}
+
+type TemplateConfigProvider interface {
+	Args() string
+
+	Values() []string
+	SkipDeps() bool
+
+	concurrencyConfig
+}
+
+type StatusesConfigProvider interface {
+	Args() string
+
+	concurrencyConfig
+}
+
+type concurrencyConfig interface {
+	Concurrency() int
+}
+
+type loggingConfig interface {
+	Logger() *zap.SugaredLogger
+}
+
+type interactive interface {
+	Interactive() bool
+}

pkg/app/run.go

@@ -0,0 +1,302 @@
+package app
+
+import (
+	"fmt"
+	"github.com/roboll/helmfile/pkg/argparser"
+	"github.com/roboll/helmfile/pkg/helmexec"
+	"github.com/roboll/helmfile/pkg/state"
+	"strings"
+)
+
+type Run struct {
+	state *state.HelmState
+	helm  helmexec.Interface
+	ctx   Context
+
+	Ask func(string) bool
+}
+
+func NewRun(st *state.HelmState, helm helmexec.Interface, ctx Context) *Run {
+	return &Run{state: st, helm: helm, ctx: ctx}
+}
+
+func (r *Run) askForConfirmation(msg string) bool {
+	if r.Ask != nil {
+		return r.Ask(msg)
+	}
+	return AskForConfirmation(msg)
+}
+
+func (r *Run) Deps(c DepsConfigProvider) []error {
+	r.helm.SetExtraArgs(argparser.GetArgs(c.Args(), r.state)...)
+
+	return r.state.UpdateDeps(r.helm)
+}
+
+func (r *Run) Repos(c ReposConfigProvider) []error {
+	r.helm.SetExtraArgs(argparser.GetArgs(c.Args(), r.state)...)
+
+	return r.ctx.SyncReposOnce(r.state, r.helm)
+}
+
+func (r *Run) DeprecatedSyncCharts(c DeprecatedChartsConfigProvider) []error {
+	st := r.state
+	helm := r.helm
+
+	affectedReleases := state.AffectedReleases{}
+	errs := st.SyncReleases(&affectedReleases, helm, c.Values(), c.Concurrency())
+	affectedReleases.DisplayAffectedReleases(c.Logger())
+	return errs
+}
+
+func (r *Run) Status(c StatusesConfigProvider) []error {
+	workers := c.Concurrency()
+
+	r.helm.SetExtraArgs(argparser.GetArgs(c.Args(), r.state)...)
+
+	return r.state.ReleaseStatuses(r.helm, workers)
+}
+
+func (r *Run) Delete(c DeleteConfigProvider) []error {
+	affectedReleases := state.AffectedReleases{}
+	purge := c.Purge()
+
+	errs := []error{}
+
+	names := make([]string, len(r.state.Releases))
+	for i, r := range r.state.Releases {
+		names[i] = fmt.Sprintf("  %s (%s)", r.Name, r.Chart)
+	}
+
+	msg := fmt.Sprintf(`Affected releases are:
+%s
+
+Do you really want to delete?
+  Helmfile will delete all your releases, as shown above.
+
+`, strings.Join(names, "\n"))
+	interactive := c.Interactive()
+	if !interactive || interactive && r.askForConfirmation(msg) {
+		r.helm.SetExtraArgs(argparser.GetArgs(c.Args(), r.state)...)
+
+		errs = r.state.DeleteReleases(&affectedReleases, r.helm, purge)
+	}
+	affectedReleases.DisplayAffectedReleases(c.Logger())
+	return errs
+}
+
+func (r *Run) Destroy(c DestroyConfigProvider) []error {
+	errs := []error{}
+	affectedReleases := state.AffectedReleases{}
+
+	names := make([]string, len(r.state.Releases))
+	for i, r := range r.state.Releases {
+		names[i] = fmt.Sprintf("  %s (%s)", r.Name, r.Chart)
+	}
+
+	msg := fmt.Sprintf(`Affected releases are:
+%s
+
+Do you really want to delete?
+  Helmfile will delete all your releases, as shown above.
+
+`, strings.Join(names, "\n"))
+	interactive := c.Interactive()
+	if !interactive || interactive && r.askForConfirmation(msg) {
+		r.helm.SetExtraArgs(argparser.GetArgs(c.Args(), r.state)...)
+
+		errs = r.state.DeleteReleases(&affectedReleases, r.helm, true)
+	}
+	affectedReleases.DisplayAffectedReleases(c.Logger())
+	return errs
+}
+
+func (r *Run) Apply(c ApplyConfigProvider) []error {
+	st := r.state
+	helm := r.helm
+	ctx := r.ctx
+
+	affectedReleases := state.AffectedReleases{}
+	if !c.SkipDeps() {
+		if errs := ctx.SyncReposOnce(st, helm); errs != nil && len(errs) > 0 {
+			return errs
+		}
+		if errs := st.BuildDeps(helm); errs != nil && len(errs) > 0 {
+			return errs
+		}
+	}
+	if errs := st.PrepareReleases(helm, "apply"); errs != nil && len(errs) > 0 {
+		return errs
+	}
+
+	// helm must be 2.11+ and helm-diff should be provided `--detailed-exitcode` in order for `helmfile apply` to work properly
+	detailedExitCode := true
+
+	releases, errs := st.DiffReleases(helm, c.Values(), c.Concurrency(), detailedExitCode, c.SuppressSecrets(), false)
+
+	releasesToBeDeleted, err := st.DetectReleasesToBeDeleted(helm)
+	if err != nil {
+		errs = append(errs, err)
+	}
+
+	fatalErrs := []error{}
+
+	noError := true
+	for _, e := range errs {
+		switch err := e.(type) {
+		case *state.ReleaseError:
+			if err.Code != 2 {
+				noError = false
+				fatalErrs = append(fatalErrs, e)
+			}
+		default:
+			noError = false
+			fatalErrs = append(fatalErrs, e)
+		}
+	}
+
+	// sync only when there are changes
+	if noError {
+		if len(releases) == 0 && len(releasesToBeDeleted) == 0 {
+			// TODO better way to get the logger
+			logger := c.Logger()
+			logger.Infof("")
+			logger.Infof("No affected releases")
+		} else {
+			names := []string{}
+			for _, r := range releases {
+				names = append(names, fmt.Sprintf("  %s (%s) UPDATED", r.Name, r.Chart))
+			}
+			for _, r := range releasesToBeDeleted {
+				names = append(names, fmt.Sprintf("  %s (%s) DELETED", r.Name, r.Chart))
+			}
+
+			msg := fmt.Sprintf(`Affected releases are:
+%s
+
+Do you really want to apply?
+  Helmfile will apply all your changes, as shown above.
+
+`, strings.Join(names, "\n"))
+			interactive := c.Interactive()
+			if !interactive || interactive && r.askForConfirmation(msg) {
+				rs := []state.ReleaseSpec{}
+				for _, r := range releases {
+					rs = append(rs, *r)
+				}
+				for _, r := range releasesToBeDeleted {
+					rs = append(rs, *r)
+				}
+
+				r.helm.SetExtraArgs(argparser.GetArgs(c.Args(), r.state)...)
+
+				st.Releases = rs
+				return st.SyncReleases(&affectedReleases, helm, c.Values(), c.Concurrency())
+			}
+		}
+	}
+
+	affectedReleases.DisplayAffectedReleases(c.Logger())
+	return fatalErrs
+}
+
+func (r *Run) Diff(c DiffConfigProvider) []error {
+	st := r.state
+	helm := r.helm
+	ctx := r.ctx
+
+	if !c.SkipDeps() {
+		if errs := ctx.SyncReposOnce(st, helm); errs != nil && len(errs) > 0 {
+			return errs
+		}
+		if errs := st.BuildDeps(helm); errs != nil && len(errs) > 0 {
+			return errs
+		}
+	}
+	if errs := st.PrepareReleases(helm, "diff"); errs != nil && len(errs) > 0 {
+		return errs
+	}
+
+	r.helm.SetExtraArgs(argparser.GetArgs(c.Args(), r.state)...)
+
+	_, errs := st.DiffReleases(helm, c.Values(), c.Concurrency(), c.DetailedExitcode(), c.SuppressSecrets(), true)
+	return errs
+}
+
+func (r *Run) Sync(c SyncConfigProvider) []error {
+	st := r.state
+	helm := r.helm
+	ctx := r.ctx
+
+	affectedReleases := state.AffectedReleases{}
+	if !c.SkipDeps() {
+		if errs := ctx.SyncReposOnce(st, helm); errs != nil && len(errs) > 0 {
+			return errs
+		}
+		if errs := st.BuildDeps(helm); errs != nil && len(errs) > 0 {
+			return errs
+		}
+	}
+	if errs := st.PrepareReleases(helm, "sync"); errs != nil && len(errs) > 0 {
+		return errs
+	}
+
+	r.helm.SetExtraArgs(argparser.GetArgs(c.Args(), r.state)...)
+
+	errs := st.SyncReleases(&affectedReleases, helm, c.Values(), c.Concurrency())
+	affectedReleases.DisplayAffectedReleases(c.Logger())
+	return errs
+}
+
+func (r *Run) Template(c TemplateConfigProvider) []error {
+	state := r.state
+	helm := r.helm
+	ctx := r.ctx
+
+	if !c.SkipDeps() {
+		if errs := ctx.SyncReposOnce(state, helm); errs != nil && len(errs) > 0 {
+			return errs
+		}
+		if errs := state.BuildDeps(helm); errs != nil && len(errs) > 0 {
+			return errs
+		}
+	}
+	if errs := state.PrepareReleases(helm, "template"); errs != nil && len(errs) > 0 {
+		return errs
+	}
+
+	args := argparser.GetArgs(c.Args(), state)
+	return state.TemplateReleases(helm, c.Values(), args, c.Concurrency())
+}
+
+func (r *Run) Test(c TestConfigProvider) []error {
+	cleanup := c.Cleanup()
+	timeout := c.Timeout()
+	concurrency := c.Concurrency()
+
+	r.helm.SetExtraArgs(argparser.GetArgs(c.Args(), r.state)...)
+
+	return r.state.TestReleases(r.helm, cleanup, timeout, concurrency)
+}
+
+func (r *Run) Lint(c LintConfigProvider) []error {
+	state := r.state
+	helm := r.helm
+	ctx := r.ctx
+
+	values := c.Values()
+	args := argparser.GetArgs(c.Args(), state)
+	workers := c.Concurrency()
+	if !c.SkipDeps() {
+		if errs := ctx.SyncReposOnce(state, helm); errs != nil && len(errs) > 0 {
+			return errs
+		}
+		if errs := state.BuildDeps(helm); errs != nil && len(errs) > 0 {
+			return errs
+		}
+	}
+	if errs := state.PrepareReleases(helm, "lint"); errs != nil && len(errs) > 0 {
+		return errs
+	}
+	return state.LintReleases(helm, values, args, workers)
+}

pkg/state/state.go

@@ -514,6 +514,9 @@ func (st *HelmState) downloadCharts(helm helmexec.Interface, dir string, concurr
 
 // TemplateReleases wrapper for executing helm template on the releases
 func (st *HelmState) TemplateReleases(helm helmexec.Interface, additionalValues []string, args []string, workerLimit int) []error {
+	// Reset the extra args if already set, not to break `helm fetch` by adding the args intended for `lint`
+	helm.SetExtraArgs()
+
 	errs := []error{}
 	// Create tmp directory and bail immediately if it fails
 	dir, err := ioutil.TempDir("", "")
@@ -577,6 +580,9 @@ func (st *HelmState) TemplateReleases(helm helmexec.Interface, additionalValues
 
 // LintReleases wrapper for executing helm lint on the releases
 func (st *HelmState) LintReleases(helm helmexec.Interface, additionalValues []string, args []string, workerLimit int) []error {
+	// Reset the extra args if already set, not to break `helm fetch` by adding the args intended for `lint`
+	helm.SetExtraArgs()
+
 	errs := []error{}
 	// Create tmp directory and bail immediately if it fails
 	dir, err := ioutil.TempDir("", "")