Readme and Usage Updation : following #22

README.md

@@ -2,21 +2,146 @@
 
 This is a Helm plugin giving your a preview of what a `helm upgrade` would change.
 It basically generates a diff between the latest deployed version of a release
-and a `helm upgrade --debug --dry-run`
+and a `helm upgrade --debug --dry-run`. This can also be used to compare two 
+revisions/versions of your helm release.
 
 <a href="https://asciinema.org/a/105326" target="_blank"><img src="https://asciinema.org/a/105326.png" /></a>
 
 ## Usage
 
 ```
-$ helm diff [flags] RELEASE CHART
+The Helm Diff Plugin
+
+* Shows a diff explaing what a helm upgrade would change:
+    This fetches the currently deployed version of a release
+  and compares it to a local chart plus values. This can be 
+  used visualize what changes a helm upgrade will perform.
+
+* Shows a diff explaing what had changed between two revisions:
+    This fetches previously deployed versions of a release
+  and compares them. This can be used visualize what changes 
+  were made during revision change.
+
+* Shows a diff explaing what a helm rollback would change:
+    This fetches the currently deployed version of a release
+  and compares it to adeployed versions of a release, that you 
+  want to rollback. This can be used visualize what changes a 
+  helm rollback will perform.
+
+Usage:
+  diff [flags]
+  diff [command]
+
+Available Commands:
+  revision    Shows diff between revision's manifests
+  rollback    Show a diff explaining what a helm rollback could perform
+  upgrade     Show a diff explaining what a helm upgrade would change.
+  version     Show version of the helm diff plugin
+
+Flags:
+  -h, --help                   help for diff
+      --no-color               remove colors from the output
+      --reset-values           reset the values to the ones built into the chart and merge in any new values
+      --reuse-values           reuse the last release's values and merge in any new values
+      --set stringArray        set values on the command line (can specify multiple or separate values with commas: key1=val1,key2=val2)
+      --suppress stringArray   allows suppression of the values listed in the diff output
+  -q, --suppress-secrets       suppress secrets in the output
+  -f, --values valueFiles      specify values in a YAML file (can specify multiple) (default [])
+      --version string         specify the exact chart version to use. If this is not specified, the latest version is used
+
+Additional help topics:
+  diff          
+
+Use "diff [command] --help" for more information about a command.
 ```
 
-### Flags:
+## Commands:
+
+### upgrade:
+
+```
+$ helm diff upgrade -h
+Show a diff explaining what a helm upgrade would change.
+
+This fetches the currently deployed version of a release
+and compares it to a chart plus values.
+This can be used visualize what changes a helm upgrade will
+perform.
+
+Usage:
+  diff upgrade [flags] [RELEASE] [CHART]
+
+Examples:
+  helm diff upgrade my-release stable/postgresql --values values.yaml
+
+Flags:
+  -h, --help                   help for upgrade
+      --reset-values           reset the values to the ones built into the chart and merge in any new values
+      --reuse-values           reuse the last release's values and merge in any new values
+      --set stringArray        set values on the command line (can specify multiple or separate values with commas: key1=val1,key2=val2)
+      --suppress stringArray   allows suppression of the values listed in the diff output
+  -q, --suppress-secrets       suppress secrets in the output
+  -f, --values valueFiles      specify values in a YAML file (can specify multiple) (default [])
+      --version string         specify the exact chart version to use. If this is not specified, the latest version is used
+
+Global Flags:
+      --no-color   remove colors from the output
+```
+
+### revision:
 
 ```
-      --set string          set values on the command line. See 'helm install -h'
-  -f, --values valueFiles   specify one or more YAML files of values (default [])
+$ helm diff revision -h
+
+This command compares the manifests details of a named release.
+
+It can be used to compare the manifests of 
+
+ - lastest REVISION with specified REVISION
+	$ helm diff revision [flags] RELEASE REVISION1
+   Example: 
+	$ helm diff revision my-release 2
+
+ - REVISION1 with REVISION2
+	$ helm diff revision [flags] RELEASE REVISION1 REVISION2
+   Example: 
+	$ helm diff revision my-release 2 3
+
+Usage:
+  diff revision [flags] RELEASE REVISION1 [REVISION2]
+
+Flags:
+  -h, --help                   help for revision
+      --suppress stringArray   allows suppression of the values listed in the diff output
+  -q, --suppress-secrets       suppress secrets in the output
+
+Global Flags:
+      --no-color   remove colors from the output
+```
+
+### rollback:
+
+```
+$ helm diff rollback -h
+
+This command compares the laset manifests details of a named release 
+with specific revision values to rollback.
+
+It forecasts/visualizes changes, that a helm rollback could perform.
+
+Usage:
+  diff rollback [flags] [RELEASE] [REVISION]
+
+Examples:
+  helm diff rollback my-release 2
+
+Flags:
+  -h, --help                   help for rollback
+      --suppress stringArray   allows suppression of the values listed in the diff output
+  -q, --suppress-secrets       suppress secrets in the output
+
+Global Flags:
+      --no-color   remove colors from the output
 ```
 
 

cmd/root.go

@@ -5,13 +5,34 @@ import (
 	"github.com/spf13/cobra"
 )
 
+const rootCmdLongUsage = `
+The Helm Diff Plugin
+
+* Shows a diff explaing what a helm upgrade would change:
+    This fetches the currently deployed version of a release
+  and compares it to a local chart plus values. This can be 
+  used visualize what changes a helm upgrade will perform.
+
+* Shows a diff explaing what had changed between two revisions:
+    This fetches previously deployed versions of a release
+  and compares them. This can be used visualize what changes 
+  were made during revision change.
+
+* Shows a diff explaing what a helm rollback would change:
+    This fetches the currently deployed version of a release
+  and compares it to adeployed versions of a release, that you 
+  want to rollback. This can be used visualize what changes a 
+  helm rollback will perform.
+`
+
 func New() *cobra.Command {
 
 	chartCommand := newChartCommand()
 
 	cmd := &cobra.Command{
 		Use:   "diff",
 		Short: "Show manifest differences",
+		Long:  rootCmdLongUsage,
 		//Alias root command to chart subcommand
 		Args: chartCommand.Args,
 		// parse the flags and check for actions like suppress-secrets, no-colors

cmd/upgrade.go

@@ -36,7 +36,7 @@ func newChartCommand() *cobra.Command {
 		Use:     "upgrade [flags] [RELEASE] [CHART]",
 		Short:   "Show a diff explaining what a helm upgrade would change.",
 		Long:    globalUsage,
-		Example: "helm diff upgrade my-release stable/postgresql --values values.yaml",
+		Example: "  helm diff upgrade my-release stable/postgresql --values values.yaml",
 		Args: func(cmd *cobra.Command, args []string) error {
 			return checkArgsLength(len(args), "release name", "chart path")
 		},