Add sub-command support to plugin downloader

Signed-off-by: Steven Sheehy <ssheehy@firescope.com>

docs/plugins.md

@@ -144,6 +144,11 @@ The defined command will be invoked with the following scheme:
 repo definition, stored in `$HELM_HOME/repository/repositories.yaml`. Downloader
 plugin is expected to dump the raw content to stdout and report errors on stderr.
 
+The downloader command also supports sub-commands or arguments, allowing you to specify
+for example `bin/mydownloader subcommand -d` in the `plugin.yaml`. This is useful
+if you want to use the same executable for the main plugin command and the downloader
+command, but with a different sub-command for each.
+
 ## Environment Variables
 
 When Helm executes a plugin, it passes the outer environment to the plugin, and

pkg/getter/plugingetter.go

@@ -21,6 +21,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"strings"
 
 	"k8s.io/helm/pkg/helm/environment"
 	"k8s.io/helm/pkg/plugin"
@@ -62,8 +63,9 @@ type pluginGetter struct {
 
 // Get runs downloader plugin command
 func (p *pluginGetter) Get(href string) (*bytes.Buffer, error) {
-	argv := []string{p.certFile, p.keyFile, p.cAFile, href}
-	prog := exec.Command(filepath.Join(p.base, p.command), argv...)
+	commands := strings.Split(p.command, " ")
+	argv := append(commands[1:], p.certFile, p.keyFile, p.cAFile, href)
+	prog := exec.Command(filepath.Join(p.base, commands[0]), argv...)
 	plugin.SetupPluginEnv(p.settings, p.name, p.base)
 	prog.Env = os.Environ()
 	buf := bytes.NewBuffer(nil)

pkg/getter/plugingetter_test.go

@@ -94,3 +94,30 @@ func TestPluginGetter(t *testing.T) {
 		t.Errorf("Expected %q, got %q", expect, got)
 	}
 }
+func TestPluginSubCommands(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("TODO: refactor this test to work on windows")
+	}
+
+	oldhh := os.Getenv("HELM_HOME")
+	defer os.Setenv("HELM_HOME", oldhh)
+	os.Setenv("HELM_HOME", "")
+
+	env := hh(false)
+	pg := newPluginGetter("echo -n", env, "test", ".")
+	g, err := pg("test://foo/bar", "", "", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	data, err := g.Get("test://foo/bar")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expect := "   test://foo/bar"
+	got := data.String()
+	if got != expect {
+		t.Errorf("Expected %q, got %q", expect, got)
+	}
+}