feat: helmfile apply [--auto-approve] (#263)

This command syncs releases only if there is any difference between the desired and the current state. It asks for an confirmation by default. Provide `--auto-approve` flag after the `apply` command to skip it.

Resolves #205

README.md

@@ -185,25 +185,28 @@ USAGE:
 
 COMMANDS:
      repos   sync repositories from state file (helm repo add && helm repo update)
-     charts  sync charts from state file (helm upgrade --install)
+     charts  sync releases from state file (helm upgrade --install)
-     diff    diff charts from state file against env (helm diff)
+     diff    diff releases from state file against env (helm diff)
      lint    lint charts from state file (helm lint)
-     sync    sync all resources from state file (repos, charts and local chart deps)
+     sync    sync all resources from state file (repos, releases and chart deps)
+     apply   apply all resources from state file only when there are changes
      status  retrieve status of releases in state file
-     delete  delete charts from state file (helm delete)
+     delete  delete releases from state file (helm delete)
-     test    tets releases from state file (helm test)
+     test    test releases from state file (helm test)
 
 GLOBAL OPTIONS:
-   --file FILE, -f FILE         load config from FILE (default: "helmfile.yaml")
+   --helm-binary value, -b value           path to helm binary
-   --quiet, -q                  silence output
+   --file helmfile.yaml, -f helmfile.yaml  load config from file or directory. defaults to helmfile.yaml or `helmfile.d`(means `helmfile.d/*.yaml`) in this preference
-   --namespace value, -n value  Set namespace. Uses the namespace set in the context by default
+   --quiet, -q                             Silence output. Equivalent to log-level warn
-   --selector,l value           Only run using the releases that match labels. Labels can take the form of foo=bar or foo!=bar.
+   --kube-context value                    Set kubectl context. Uses current context by default
-	                              A release must match all labels in a group in order to be used. Multiple groups can be specified at once.
+   --log-level value                       Set log level, default info
-	                              --selector tier=frontend,tier!=proxy --selector tier=backend. Will match all frontend, non-proxy releases AND all backend releases.
+   --namespace value, -n value             Set namespace. Uses the namespace set in the context by default
-	                              The name of a release can be used as a label. --selector name=myrelease
+   --selector value, -l value              Only run using the releases that match labels. Labels can take the form of foo=bar or foo!=bar.
-   --kube-context value         Set kubectl context. Uses current context by default
+                                           A release must match all labels in a group in order to be used. Multiple groups can be specified at once.
-   --help, -h                   show help
+                                           --selector tier=frontend,tier!=proxy --selector tier=backend. Will match all frontend, non-proxy releases AND all backend releases.
-   --version, -v                print the version
+                                           The name of a release can be used as a label. --selector name=myrelease
+   --help, -h                              show help
+   --version, -v                           print the version
 ```
 
 ### sync
@@ -224,6 +227,12 @@ To supply the diff functionality Helmfile needs the [helm-diff](https://github.c
 you should be able to simply execute `helm plugin install https://github.com/databus23/helm-diff`. For more details
 please look at their [documentation](https://github.com/databus23/helm-diff#helm-diff-plugin).
 
+### apply
+
+The `helmfile apply` sub-command begins by executing `diff`. If `diff` finds that there is any changes, `sync` is executed after prompting you for an confirmation. `--auto-approve` skips the confirmation.
+
+An expected use-case of `apply` is to schedule it to run periodically, so that you can auto-fix skews between the desired and the current state of your apps running on Kubernetes clusters.
+
 ### delete
 
 The `helmfile delete` sub-command deletes all the releases defined in the manfiests

ask.go

@@ -0,0 +1,33 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"os"
+	"strings"
+)
+
+// 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 {
+	reader := bufio.NewReader(os.Stdin)
+
+	for {
+		fmt.Printf("%s [y/n]: ", s)
+
+		response, err := reader.ReadString('\n')
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		response = strings.ToLower(strings.TrimSpace(response))
+
+		if response == "y" || response == "yes" {
+			return true
+		} else if response == "n" || response == "no" {
+			return false
+		}
+	}
+}

main.go

@@ -184,25 +184,7 @@ func main() {
 			},
 			Action: func(c *cli.Context) error {
 				return eachDesiredStateDo(c, func(state *state.HelmState, helm helmexec.Interface) []error {
-					args := args.GetArgs(c.String("args"), state)
+					return executeDiffCommand(c, state, helm, c.Bool("detailed-exitcode"))
-					if len(args) > 0 {
-						helm.SetExtraArgs(args...)
-					}
-					if c.GlobalString("helm-binary") != "" {
-						helm.SetHelmBinary(c.GlobalString("helm-binary"))
-					}
-
-					if c.Bool("sync-repos") {
-						if errs := state.SyncRepos(helm); errs != nil && len(errs) > 0 {
-							return errs
-						}
-					}
-
-					values := c.StringSlice("values")
-					workers := c.Int("concurrency")
-					detailedExitCode := c.Bool("detailed-exitcode")
-
-					return state.DiffReleases(helm, values, workers, detailedExitCode)
 				})
 			},
 		},
@@ -263,26 +245,64 @@ func main() {
 			},
 			Action: func(c *cli.Context) error {
 				return eachDesiredStateDo(c, func(state *state.HelmState, helm helmexec.Interface) []error {
-					if errs := state.SyncRepos(helm); errs != nil && len(errs) > 0 {
+					return executeSyncCommand(c, state, helm)
-						return errs
+				})
+			},
+		},
+		{
+			Name:  "apply",
+			Usage: "apply all resources from state file only when there are changes",
+			Flags: []cli.Flag{
+				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",
+				},
+				cli.StringFlag{
+					Name:  "args",
+					Value: "",
+					Usage: "pass args to helm exec",
+				},
+				cli.BoolFlag{
+					Name:  "auto-approve",
+					Usage: "Skip interactive approval before applying",
+				},
+			},
+			Action: func(c *cli.Context) error {
+				return eachDesiredStateDo(c, func(state *state.HelmState, helm helmexec.Interface) []error {
+					errs := executeDiffCommand(c, state, helm, true)
+
+					// sync only when there are changes
+					if len(errs) > 0 {
+						allErrsIndicateChanges := true
+						for _, err := range errs {
+							switch e := err.(type) {
+							case *exec.ExitError:
+								status := e.Sys().(syscall.WaitStatus)
+								// `helm diff --detailed-exitcode` returns 2 when there are changes
+								allErrsIndicateChanges = allErrsIndicateChanges && status.ExitStatus() == 2
+							default:
+								allErrsIndicateChanges = false
+							}
+						}
+
+						msg := `Do you really want to apply?
+  Helmfile will apply all your changes, as shown above.
+
+`
+						if allErrsIndicateChanges {
+							autoApprove := c.Bool("auto-approve")
+							if autoApprove || !autoApprove && askForConfirmation(msg) {
+								return executeSyncCommand(c, state, helm)
+							}
+						}
 					}
 
-					if errs := state.UpdateDeps(helm); errs != nil && len(errs) > 0 {
+					return errs
-						return errs
-					}
-
-					args := args.GetArgs(c.String("args"), state)
-					if len(args) > 0 {
-						helm.SetExtraArgs(args...)
-					}
-					if c.GlobalString("helm-binary") != "" {
-						helm.SetHelmBinary(c.GlobalString("helm-binary"))
-					}
-
-					values := c.StringSlice("values")
-					workers := c.Int("concurrency")
-
-					return state.SyncReleases(helm, values, workers)
 				})
 			},
 		},
@@ -393,6 +413,50 @@ func main() {
 	}
 }
 
+func executeSyncCommand(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
+	}
+
+	args := args.GetArgs(c.String("args"), state)
+	if len(args) > 0 {
+		helm.SetExtraArgs(args...)
+	}
+	if c.GlobalString("helm-binary") != "" {
+		helm.SetHelmBinary(c.GlobalString("helm-binary"))
+	}
+
+	values := c.StringSlice("values")
+	workers := c.Int("concurrency")
+
+	return state.SyncReleases(helm, values, workers)
+}
+
+func executeDiffCommand(c *cli.Context, state *state.HelmState, helm helmexec.Interface, detailedExitCode bool) []error {
+	args := args.GetArgs(c.String("args"), state)
+	if len(args) > 0 {
+		helm.SetExtraArgs(args...)
+	}
+	if c.GlobalString("helm-binary") != "" {
+		helm.SetHelmBinary(c.GlobalString("helm-binary"))
+	}
+
+	if c.Bool("sync-repos") {
+		if errs := state.SyncRepos(helm); errs != nil && len(errs) > 0 {
+			return errs
+		}
+	}
+
+	values := c.StringSlice("values")
+	workers := c.Int("concurrency")
+
+	return state.DiffReleases(helm, values, workers, detailedExitCode)
+}
+
 func eachDesiredStateDo(c *cli.Context, converge func(*state.HelmState, helmexec.Interface) []error) error {
 	fileOrDirPath := c.GlobalString("file")
 	desiredStateFiles, err := findDesiredStateFiles(fileOrDirPath)