Feature Request: Diff to compare rollback

README.md

@@ -1,24 +1,102 @@
 # Helm Diff Plugin
 
-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`
+This is a Helm plugin giving your a preview of what a `helm upgrade` or `helm rollback` 
+would change. It basically generates a diff between the latest deployed version of a 
+releaseand a `helm upgrade --debug --dry-run` when used with `upgrade` command or with 
+the specified rollback revision of release. 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
+$ helm diff
+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 a helm rollback would change:
+    This fetches the currently deployed version of a release
+  and compares it rollback revision. This can be 
+  used visualize what changes a helm rollback 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.
+
+Usage:
+  diff [command]
+
+Available Commands:
+  revision    Shows diff between revision's manifests
+  rollback    visualize changes, that a helm rollback could perform
+  upgrade     visualize changes, that a helm upgrade could perform
+  version     print the version information
+
+Flags:
+  -h, --help   help for diff
+
+Use "diff [command] --help" for more information about a command.
+```
+
+## Commands:
+
+### upgrade:
+
+```
+$ helm diff upgrade -h
+This command compares the manifests details of a named release 
+with values generated form charts.
+
+It forecasts/visualizes changes, that a helm upgrade could perform.
+
+Usage:
+  diff upgrade [flags] [RELEASE] [CHART]
+
+Flags:
+      --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 [])
+```
+
+### rollback:
+
 ```
+$ helm diff rollback -h
+This command compares the laset manifests details of a named release 
+with specific revision values to rollback.
 
-### Flags:
+It forecasts/visualizes changes, that a helm rollback could perform.
+
+Usage:
+  diff rollback [flags] [RELEASE] 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 [])
+
+### revision:
+
 ```
+$ 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] REVISION
+
+ - REVISION1 with REVISION2
+	$ helm diff revision [flags] [RELEASE] REVISION1 REVISION1
+
+Usage:
+  diff revision [flags] [RELEASE] REVISION1 REVISION2
+```
 
 ## Install
 

helm.go

@@ -76,7 +76,7 @@ func locateChartPath(name, version string, verify bool, keyring string) (string,
 		dl.Verify = downloader.VerifyAlways
 	}
 
-	filename, _, err := dl.DownloadTo(name, version, ".")
+	filename, _, err := dl.DownloadTo(name, version, helmpath.Home(homePath()).Archive())
 	if err == nil {
 		lname, err := filepath.Abs(filename)
 		if err != nil {