vendor: add buildkit

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

vendor/github.com/moby/buildkit/session/auth/authprovider/authprovider.go

@@ -0,0 +1,44 @@
+package authprovider
+
+import (
+	"context"
+	"io/ioutil"
+
+	"github.com/docker/cli/cli/config"
+	"github.com/docker/cli/cli/config/configfile"
+	"github.com/moby/buildkit/session"
+	"github.com/moby/buildkit/session/auth"
+	"google.golang.org/grpc"
+)
+
+func NewDockerAuthProvider() session.Attachable {
+	return &authProvider{
+		config: config.LoadDefaultConfigFile(ioutil.Discard),
+	}
+}
+
+type authProvider struct {
+	config *configfile.ConfigFile
+}
+
+func (ap *authProvider) Register(server *grpc.Server) {
+	auth.RegisterAuthServer(server, ap)
+}
+
+func (ap *authProvider) Credentials(ctx context.Context, req *auth.CredentialsRequest) (*auth.CredentialsResponse, error) {
+	if req.Host == "registry-1.docker.io" {
+		req.Host = "https://index.docker.io/v1/"
+	}
+	ac, err := ap.config.GetAuthConfig(req.Host)
+	if err != nil {
+		return nil, err
+	}
+	res := &auth.CredentialsResponse{}
+	if ac.IdentityToken != "" {
+		res.Secret = ac.IdentityToken
+	} else {
+		res.Username = ac.Username
+		res.Secret = ac.Password
+	}
+	return res, nil
+}