loading external plugins

Signed-off-by: Vicente Zepeda Mas <vzepedamas@suse.com>
(cherry picked from commit 3f7304e52ec57a0701f307c4d048c4269455d04a)

cmd/helm/helm_test.go

@@ -25,7 +25,6 @@ import (
 
 	shellwords "github.com/mattn/go-shellwords"
 	"github.com/spf13/cobra"
-
 	"k8s.io/helm/internal/test"
 	"k8s.io/helm/pkg/hapi/release"
 	"k8s.io/helm/pkg/helm"

cmd/helm/load_plugins.go

@@ -25,7 +25,6 @@ import (
 
 	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
-
 	"k8s.io/helm/pkg/plugin"
 )
 
@@ -41,8 +40,9 @@ func loadPlugins(baseCmd *cobra.Command, out io.Writer) {
 		return
 	}
 
+	pluginsDirs := []string{settings.PluginDirs(), settings.SystemPluginsDir}
 	// debug("HELM_PLUGIN_DIRS=%s", settings.PluginDirs())
-	found, err := findPlugins(settings.PluginDirs())
+	found, err := findPlugins(pluginsDirs)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "failed to load plugins: %s", err)
 		return
@@ -137,15 +137,17 @@ func manuallyProcessArgs(args []string) ([]string, []string) {
 }
 
 // findPlugins returns a list of YAML files that describe plugins.
-func findPlugins(plugdirs string) ([]*plugin.Plugin, error) {
+func findPlugins(plugdirs []string) ([]*plugin.Plugin, error) {
 	found := []*plugin.Plugin{}
 	// Let's get all UNIXy and allow path separators
-	for _, p := range filepath.SplitList(plugdirs) {
-		matches, err := plugin.LoadAll(p)
-		if err != nil {
-			return matches, err
+	for _, pd := range plugdirs {
+		for _, p := range filepath.SplitList(pd) {
+			matches, err := plugin.LoadAll(p)
+			if err != nil {
+				return matches, err
+			}
+			found = append(found, matches...)
 		}
-		found = append(found, matches...)
 	}
 	return found, nil
 }

cmd/helm/plugin_list.go

@@ -19,10 +19,9 @@ import (
 	"fmt"
 	"io"
 
-	"k8s.io/helm/pkg/helm/helmpath"
-
 	"github.com/gosuri/uitable"
 	"github.com/spf13/cobra"
+	"k8s.io/helm/pkg/helm/helmpath"
 )
 
 type pluginListOptions struct {
@@ -44,7 +43,8 @@ func newPluginListCmd(out io.Writer) *cobra.Command {
 
 func (o *pluginListOptions) run(out io.Writer) error {
 	debug("pluginDirs: %s", settings.PluginDirs())
-	plugins, err := findPlugins(settings.PluginDirs())
+	directories := []string{settings.PluginDirs(), settings.SystemPluginsDir}
+	plugins, err := findPlugins(directories)
 	if err != nil {
 		return err
 	}

cmd/helm/plugin_remove.go

@@ -23,7 +23,6 @@ import (
 
 	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
-
 	"k8s.io/helm/pkg/helm/helmpath"
 	"k8s.io/helm/pkg/plugin"
 )
@@ -59,7 +58,7 @@ func (o *pluginRemoveOptions) complete(args []string) error {
 
 func (o *pluginRemoveOptions) run(out io.Writer) error {
 	debug("loading installed plugins from %s", settings.PluginDirs())
-	plugins, err := findPlugins(settings.PluginDirs())
+	plugins, err := findPlugins([]string{settings.PluginDirs()})
 	if err != nil {
 		return err
 	}

cmd/helm/plugin_test.go

@@ -23,10 +23,9 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/spf13/cobra"
 	"k8s.io/helm/pkg/helm/helmpath"
 	"k8s.io/helm/pkg/plugin"
-
-	"github.com/spf13/cobra"
 )
 
 func TestManuallyProcessArgs(t *testing.T) {
@@ -65,6 +64,7 @@ func TestLoadPlugins(t *testing.T) {
 	defer resetEnv()()
 
 	settings.Home = "testdata/helmhome"
+	settings.SystemPluginsDir = "test"
 
 	os.Setenv("HELM_HOME", settings.Home.String())
 	hh := settings.Home

cmd/helm/plugin_update.go

@@ -23,7 +23,6 @@ import (
 
 	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
-
 	"k8s.io/helm/pkg/helm/helmpath"
 	"k8s.io/helm/pkg/plugin"
 	"k8s.io/helm/pkg/plugin/installer"
@@ -61,7 +60,7 @@ func (o *pluginUpdateOptions) complete(args []string) error {
 func (o *pluginUpdateOptions) run(out io.Writer) error {
 	installer.Debug = settings.Debug
 	debug("loading installed plugins from %s", settings.PluginDirs())
-	plugins, err := findPlugins(settings.PluginDirs())
+	plugins, err := findPlugins([]string{settings.PluginDirs()})
 	if err != nil {
 		return err
 	}

docs/plugins.md

@@ -21,6 +21,10 @@ Helm plugins have the following features:
 - They can be written in any programming language.
 - They integrate with Helm, and will show up in `helm help` and other places.
 
+## Plugins Backends
+
+### Native
+
 Helm plugins live in `$(helm home)/plugins`.
 
 The Helm plugin model is partially modeled on Git's plugin model. To that end,
@@ -29,9 +33,27 @@ plugins being the _plumbing_. This is a shorthand way of suggesting that
 Helm provides the user experience and top level processing logic, while the
 plugins do the "detail work" of performing a desired action.
 
-## Installing a Plugin
+### External
+
+Helm external plugins can live anywhere in your `PATH`.
+
+These plugins become necessary because of systems that are closed to manual
+configuration and the only way to get software installed is by an administrator
+managing the plugins at system level via a linux distribution package manager.
+
+These plugins are going to be available globally. All users may use the plugin,
+not limited to a user like Native Plugins.
+
+The only condition for these plugins is that they provide the yaml description
+in the folder `/usr/share`; and the full path should look like this
+`/usr/share/<helm-external-plugin>/plugin.yaml`.
 
-Plugins are installed using the `$ helm plugin install <path|url>` command. You can pass in a path to a plugin on your local file system or a url of a remote VCS repo. The `helm plugin install` command clones or copies the plugin at the path/url given into `$ (helm home)/plugins`
+## Installing a Native Plugin
+
+Native Plugins are installed using the `$ helm plugin install <path|url>` command.
+You can pass in a path to a plugin on your local file system or a url of a remote
+VCS repo. The `helm plugin install` command clones or copies the plugin at the
+path/url given into `$ (helm home)/plugins`
 
 ```console
 $ helm plugin install https://github.com/technosophos/helm-template
@@ -42,7 +64,12 @@ If you have a plugin tar distribution, simply untar the plugin into the
 
 You can also install tarball plugins directly from url by issuing `helm plugin install http://domain/path/to/plugin.tar.gz`
 
-## Building Plugins
+## Installing an External Plugin
+
+Each external plugin has its own installation process, you should check with the plugin's
+site/help to get the correct information.
+
+## Building Native Plugins
 
 In many ways, a plugin is similar to a chart. Each plugin has a top-level
 directory, and then a `plugin.yaml` file.
@@ -73,7 +100,7 @@ ignoreFlags: false
 command: "$HELM_PLUGIN_DIR/keybase.sh"
 ```
 
-The `name` is the name of the plugin. When Helm executes it plugin, this is the
+The `name` is the name of the plugin. When Helm executes a plugin, this is the
 name it will use (e.g. `helm NAME` will invoke this plugin).
 
 _`name` should match the directory name._ In our example above, that means the
@@ -111,8 +138,8 @@ There are some strategies for working with plugin commands:
   Helm will use `usage` and `description` for `helm help` and `helm help myplugin`,
   but will not handle `helm myplugin --help`.
 
-## Downloader Plugins
-By default, Helm is able to pull Charts using HTTP/S. As of Helm 2.4.0, plugins
+## Downloader Native Plugins
+By default, Helm is able to fetch Charts using HTTP/S. As of Helm 2.4.0, plugins
 can have a special capability to download Charts from arbitrary sources.
 
 Plugins shall declare this special capability in the `plugin.yaml` file (top level):
@@ -137,6 +164,66 @@ 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.
 
+## External Plugins Breakout
+
+External plugins have to comply with two conditions:
+
+- Be sure it is accessible by being in the `PATH`.
+
+- Have the `plugin.yaml` installed in the `/usr/share/<external-plugin>` folder.
+
+### Example
+
+```console
+/usr/
+  |- bin/
+    |- helm-mirror
+  |- share/
+      |- helm-mirror
+        |- plugin.yaml
+```
+
+### plugin.yaml for External Plugins
+
+```
+name: "mirror"
+version: "0.1.0"
+usage: "Mirrors Helm charts to a local folder"
+description: "Mirrors Helm charts to a local folder"
+ignoreFlags: false
+useTunnel: false
+command: "/usr/bin/helm-mirror"
+```
+
+The `name` is the name of the plugin. When Helm executes a plugin, this is the
+name it will use (e.g. `helm NAME` will invoke this plugin).
+
+Restrictions on `name`:
+
+- `name` cannot duplicate one of the existing `helm` top-level commands.
+- `name` must be restricted to the characters ASCII a-z, A-Z, 0-9, `_` and `-`.
+
+`version` is the SemVer 2 version of the plugin.
+
+`usage` and `description` are both used to generate the help text of a command.
+
+The `ignoreFlags` switch tells Helm to _not_ pass flags to the plugin. So if a
+plugin is called with `helm myplugin --foo` and `ignoreFlags: true`, then `--foo`
+is silently discarded.
+
+The `useTunnel` switch indicates that the plugin needs a tunnel to Tiller. This
+should be set to `true` _anytime a plugin talks to Tiller_. It will cause Helm
+to open a tunnel, and then set `$TILLER_HOST` to the right local address for that
+tunnel. But don't worry: if Helm detects that a tunnel is not necessary because
+Tiller is running locally, it will not create the tunnel.
+
+Finally, and most importantly, `command` is the command that this plugin will
+execute when it is called. Environment variables are interpolated before the plugin
+is executed. The pattern above illustrates the preferred way to indicate where
+the plugin program lives.
+
+> NOTE: For External Plugins the `plugin.yaml` definition **MUST NOT** contain any `Hooks`.
+
 ## Environment Variables
 
 When Helm executes a plugin, it passes the outer environment to the plugin, and

pkg/getter/plugingetter.go

@@ -30,7 +30,8 @@ import (
 // collectPlugins scans for getter plugins.
 // This will load plugins according to the environment.
 func collectPlugins(settings environment.EnvSettings) (Providers, error) {
-	plugins, err := plugin.FindPlugins(settings.PluginDirs())
+	pluginsDirs := []string{settings.PluginDirs(), settings.SystemPluginsDir}
+	plugins, err := plugin.FindPlugins(pluginsDirs)
 	if err != nil {
 		return nil, err
 	}

pkg/helm/environment/environment.go

@@ -28,7 +28,6 @@ import (
 
 	"github.com/spf13/pflag"
 	"k8s.io/client-go/util/homedir"
-
 	"k8s.io/helm/pkg/helm/helmpath"
 )
 
@@ -47,6 +46,8 @@ type EnvSettings struct {
 	KubeContext string
 	// Debug indicates whether or not Helm is running in Debug mode.
 	Debug bool
+	// SystemPluginsDir system dir plugin
+	SystemPluginsDir string
 }
 
 // AddFlags binds flags to the given flagset.
@@ -55,6 +56,7 @@ func (s *EnvSettings) AddFlags(fs *pflag.FlagSet) {
 	fs.StringVarP(&s.Namespace, "namespace", "n", "", "namespace scope for this request")
 	fs.StringVar(&s.KubeConfig, "kubeconfig", "", "path to the kubeconfig file")
 	fs.StringVar(&s.KubeContext, "kube-context", "", "name of the kubeconfig context to use")
+	fs.StringVar(&s.SystemPluginsDir, "system-plugins-dir", "/usr/share", "path system plugins configfiles")
 	fs.BoolVar(&s.Debug, "debug", false, "enable verbose output")
 }
 

pkg/helm/environment/environment_test.go

@@ -18,12 +18,12 @@ package environment
 
 import (
 	"os"
+	"reflect"
 	"strings"
 	"testing"
 
-	"k8s.io/helm/pkg/helm/helmpath"
-
 	"github.com/spf13/pflag"
+	"k8s.io/helm/pkg/helm/helmpath"
 )
 
 func TestEnvSettings(t *testing.T) {
@@ -90,7 +90,7 @@ func TestEnvSettings(t *testing.T) {
 			if settings.Home != helmpath.Home(tt.home) {
 				t.Errorf("expected home %q, got %q", tt.home, settings.Home)
 			}
-			if settings.PluginDirs() != tt.plugins {
+			if !reflect.DeepEqual(settings.PluginDirs(), tt.plugins) {
 				t.Errorf("expected plugins %q, got %q", tt.plugins, settings.PluginDirs())
 			}
 			if settings.Debug != tt.debug {

pkg/plugin/plugin.go

@@ -21,9 +21,8 @@ import (
 	"path/filepath"
 	"strings"
 
-	helm_env "k8s.io/helm/pkg/helm/environment"
-
 	"github.com/ghodss/yaml"
+	helm_env "k8s.io/helm/pkg/helm/environment"
 )
 
 const pluginFileName = "plugin.yaml"
@@ -148,15 +147,17 @@ func LoadAll(basedir string) ([]*Plugin, error) {
 }
 
 // FindPlugins returns a list of YAML files that describe plugins.
-func FindPlugins(plugdirs string) ([]*Plugin, error) {
+func FindPlugins(plugdirs []string) ([]*Plugin, error) {
 	found := []*Plugin{}
 	// Let's get all UNIXy and allow path separators
-	for _, p := range filepath.SplitList(plugdirs) {
-		matches, err := LoadAll(p)
-		if err != nil {
-			return matches, err
+	for _, pd := range plugdirs {
+		for _, p := range filepath.SplitList(pd) {
+			matches, err := LoadAll(p)
+			if err != nil {
+				return matches, err
+			}
+			found = append(found, matches...)
 		}
-		found = append(found, matches...)
 	}
 	return found, nil
 }