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plugin.go
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plugin.go
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package main
import (
"fmt"
"io"
"os"
"os/exec"
"path/filepath"
"strings"
"github.com/spf13/cobra"
"k8s.io/helm/pkg/plugin"
"github.com/Azure/draft/pkg/draft/draftpath"
)
const (
pluginHelp = `Manage client-side Draft plugins.`
pluginEnvVar = `DRAFT_PLUGIN`
)
func newPluginCmd(out io.Writer) *cobra.Command {
cmd := &cobra.Command{
Use: "plugin",
Short: "add Draft plugins",
Long: pluginHelp,
}
cmd.AddCommand(
newPluginInstallCmd(out),
newPluginListCmd(out),
newPluginRemoveCmd(out),
newPluginUpdateCmd(out),
)
return cmd
}
// findPlugins returns a list of YAML files that describe plugins.
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
}
found = append(found, matches...)
}
return found, nil
}
func pluginDirPath(home draftpath.Home) string {
plugdirs := os.Getenv(pluginEnvVar)
if plugdirs == "" {
plugdirs = home.Plugins()
}
return plugdirs
}
// loadPlugins loads plugins into the command list.
//
// This follows a different pattern than the other commands because it has
// to inspect its environment and then add commands to the base command
// as it finds them.
func loadPlugins(baseCmd *cobra.Command, home draftpath.Home, out io.Writer, in io.Reader) {
plugdirs := pluginDirPath(home)
found, err := findPlugins(plugdirs)
if err != nil {
fmt.Fprintf(os.Stderr, "failed to load plugins: %s", err)
return
}
// Now we create commands for all of these.
for _, plug := range found {
plug := plug
md := plug.Metadata
if md.Usage == "" {
md.Usage = fmt.Sprintf("the %q plugin", md.Name)
}
c := &cobra.Command{
Use: md.Name,
Short: md.Usage,
Long: md.Description,
RunE: func(cmd *cobra.Command, args []string) error {
k, u := manuallyProcessArgs(args)
if err := cmd.Parent().ParseFlags(k); err != nil {
return err
}
// Call setupEnv before PrepareCommand because
// PrepareCommand uses os.ExpandEnv and expects the
// setupEnv vars.
setupPluginEnv(md.Name, plug.Dir, plugdirs, draftpath.Home(homePath()))
main, argv := plug.PrepareCommand(u)
prog := exec.Command(main, argv...)
prog.Env = os.Environ()
prog.Stdout = out
prog.Stderr = os.Stderr
prog.Stdin = in
if err := prog.Run(); err != nil {
if eerr, ok := err.(*exec.ExitError); ok {
os.Stderr.Write(eerr.Stderr)
return fmt.Errorf("plugin %q exited with error", md.Name)
}
return err
}
return nil
},
// This passes all the flags to the subcommand.
DisableFlagParsing: true,
}
if md.UseTunnel {
c.PersistentPreRunE = func(cmd *cobra.Command, args []string) error {
// Parse the parent flag, but not the local flags.
k, _ := manuallyProcessArgs(args)
if err := c.Parent().ParseFlags(k); err != nil {
return err
}
return setupConnection(cmd, args)
}
}
baseCmd.AddCommand(c)
}
}
// manuallyProcessArgs processes an arg array, removing special args.
//
// Returns two sets of args: known and unknown (in that order)
func manuallyProcessArgs(args []string) ([]string, []string) {
known := []string{}
unknown := []string{}
kvargs := []string{"--host", "--kube-context", "--home"}
knownArg := func(a string) bool {
for _, pre := range kvargs {
if strings.HasPrefix(a, pre+"=") {
return true
}
}
return false
}
for i := 0; i < len(args); i++ {
switch a := args[i]; a {
case "--debug":
known = append(known, a)
case "--host", "--kube-context", "--home":
known = append(known, a, args[i+1])
i++
default:
if knownArg(a) {
known = append(known, a)
continue
}
unknown = append(unknown, a)
}
}
return known, unknown
}
// runHook will execute a plugin hook.
func runHook(p *plugin.Plugin, event string) error {
hook := p.Metadata.Hooks.Get(event)
if hook == "" {
return nil
}
prog := exec.Command("sh", "-c", hook)
debug("running %s hook: %s", event, prog)
home := draftpath.Home(homePath())
setupPluginEnv(p.Metadata.Name, p.Dir, home.Plugins(), home)
prog.Stdout, prog.Stderr = os.Stdout, os.Stderr
if err := prog.Run(); err != nil {
if eerr, ok := err.(*exec.ExitError); ok {
os.Stderr.Write(eerr.Stderr)
return fmt.Errorf("plugin %s hook for %q exited with error", event, p.Metadata.Name)
}
return err
}
return nil
}
// setupPluginEnv prepares os.Env for plugins. It operates on os.Env because
// the plugin subsystem itself needs access to the environment variables
// created here.
func setupPluginEnv(shortname, base, plugdirs string, home draftpath.Home) {
// Set extra env vars:
for key, val := range map[string]string{
"DRAFT_PLUGIN_NAME": shortname,
"DRAFT_PLUGIN_DIR": base,
"DRAFT_BIN": os.Args[0],
// Set vars that may not have been set, and save client the
// trouble of re-parsing.
pluginEnvVar: pluginDirPath(home),
homeEnvVar: home.String(),
hostEnvVar: draftHost,
// Set vars that convey common information.
"DRAFT_PACKS_HOME": home.Packs(),
} {
os.Setenv(key, val)
}
if flagDebug {
os.Setenv("DRAFT_DEBUG", "1")
}
}