Implement credential programs reading from Stdin.

Signed-off-by: David Calavera <david.calavera@gmail.com>

plugin/plugin.go

@@ -1,38 +1,112 @@
 package plugin
 
 import (
-	"net/rpc"
+	"bufio"
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"os"
+	"strings"
 
 	"github.com/calavera/docker-credential-helpers/credentials"
-	"github.com/hashicorp/go-plugin"
 )
 
-var handshakeConfig = plugin.HandshakeConfig{
-	ProtocolVersion:  1,
-	MagicCookieKey:   "DOCKER_CREDENTIAL_PLUGIN",
-	MagicCookieValue: "nyzGgJQpfOYO$oUVHo4RsLaYaNmCqeWLEqZnZG}peMVq4nXdFp",
+type credentialsGetResponse struct {
+	Username string
+	Password string
 }
 
-type credentialsPlugin struct {
-	helper credentials.Helper
-}
-
-func (p *credentialsPlugin) Server(*plugin.MuxBroker) (interface{}, error) {
-	return p, nil
-}
-
-func (*credentialsPlugin) Client(b *plugin.MuxBroker, c *rpc.Client) (interface{}, error) {
-	return nil, nil
-}
-
-// Serve initializes the socket connection to a store helper.
+// Serve initializes the store helper and parses the action argument.
 func Serve(helper credentials.Helper) {
-	pluginMap := map[string]plugin.Plugin{
-		"credentials": &credentialsPlugin{helper},
+	if err := handleCommand(helper); err != nil {
+		fmt.Fprintf(os.Stdout, "%v\n", err)
+		os.Exit(1)
+	}
+}
+
+func handleCommand(helper credentials.Helper) error {
+	if len(os.Args) != 2 {
+		return fmt.Errorf("Usage: %s <store|get|erase>", os.Args[0])
 	}
 
-	plugin.Serve(&plugin.ServeConfig{
-		HandshakeConfig: handshakeConfig,
-		Plugins:         pluginMap,
-	})
+	switch os.Args[1] {
+	case "store":
+		return store(helper, os.Stdin)
+	case "get":
+		return get(helper, os.Stdin, os.Stdout)
+	case "erase":
+		return erase(helper, os.Stdin)
+	}
+	return fmt.Errorf("Usage: %s <store|get|erase>", os.Args[0])
+}
+
+func store(helper credentials.Helper, reader io.Reader) error {
+	scanner := bufio.NewScanner(reader)
+
+	buffer := new(bytes.Buffer)
+	for scanner.Scan() {
+		buffer.Write(scanner.Bytes())
+	}
+
+	if err := scanner.Err(); err != nil && err != io.EOF {
+		return err
+	}
+
+	var creds credentials.Credentials
+	if err := json.NewDecoder(buffer).Decode(&creds); err != nil {
+		return err
+	}
+
+	return helper.Add(&creds)
+}
+
+func get(helper credentials.Helper, reader io.Reader, writer io.Writer) error {
+	scanner := bufio.NewScanner(reader)
+
+	buffer := new(bytes.Buffer)
+	for scanner.Scan() {
+		buffer.Write(scanner.Bytes())
+	}
+
+	if err := scanner.Err(); err != nil && err != io.EOF {
+		return err
+	}
+
+	serverURL := strings.TrimSpace(buffer.String())
+
+	username, password, err := helper.Get(serverURL)
+	if err != nil {
+		return err
+	}
+
+	resp := credentialsGetResponse{
+		Username: username,
+		Password: password,
+	}
+
+	buffer.Reset()
+	if err := json.NewEncoder(buffer).Encode(resp); err != nil {
+		return err
+	}
+
+	fmt.Fprint(writer, buffer.String())
+	return nil
+}
+
+func erase(helper credentials.Helper, reader io.Reader) error {
+	scanner := bufio.NewScanner(reader)
+
+	buffer := new(bytes.Buffer)
+	for scanner.Scan() {
+		buffer.Write(scanner.Bytes())
+	}
+
+	if err := scanner.Err(); err != nil && err != io.EOF {
+		return err
+	}
+
+	serverURL := strings.TrimSpace(buffer.String())
+
+	return helper.Delete(serverURL)
 }