add reload and plugin support for hop

internal/plugin/plugin.go

@@ -0,0 +1,91 @@
+package plugin
+
+import (
+	"context"
+	"crypto/tls"
+	"net/http"
+	"time"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/backoff"
+	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/credentials/insecure"
+)
+
+type Options struct {
+	Token     string
+	TLSConfig *tls.Config
+	Header    http.Header
+	Timeout   time.Duration
+}
+
+type Option func(opts *Options)
+
+func TokenOption(token string) Option {
+	return func(opts *Options) {
+		opts.Token = token
+	}
+}
+
+func TLSConfigOption(cfg *tls.Config) Option {
+	return func(opts *Options) {
+		opts.TLSConfig = cfg
+	}
+}
+
+func HeaderOption(header http.Header) Option {
+	return func(opts *Options) {
+		opts.Header = header
+	}
+}
+
+func TimeoutOption(timeout time.Duration) Option {
+	return func(opts *Options) {
+		opts.Timeout = timeout
+	}
+}
+
+func NewGRPCConn(addr string, opts *Options) (*grpc.ClientConn, error) {
+	grpcOpts := []grpc.DialOption{
+		// grpc.WithBlock(),
+		grpc.WithConnectParams(grpc.ConnectParams{
+			Backoff: backoff.DefaultConfig,
+		}),
+		grpc.FailOnNonTempDialError(true),
+	}
+	if opts.TLSConfig != nil {
+		grpcOpts = append(grpcOpts,
+			grpc.WithAuthority(opts.TLSConfig.ServerName),
+			grpc.WithTransportCredentials(credentials.NewTLS(opts.TLSConfig)),
+		)
+	} else {
+		grpcOpts = append(grpcOpts, grpc.WithTransportCredentials(insecure.NewCredentials()))
+	}
+	if opts.Token != "" {
+		grpcOpts = append(grpcOpts, grpc.WithPerRPCCredentials(&rpcCredentials{token: opts.Token}))
+	}
+	return grpc.Dial(addr, grpcOpts...)
+}
+
+type rpcCredentials struct {
+	token string
+}
+
+func (c *rpcCredentials) GetRequestMetadata(ctx context.Context, uri ...string) (map[string]string, error) {
+	return map[string]string{
+		"token": c.token,
+	}, nil
+}
+
+func (c *rpcCredentials) RequireTransportSecurity() bool {
+	return false
+}
+
+func NewHTTPClient(opts *Options) *http.Client {
+	return &http.Client{
+		Timeout: opts.Timeout,
+		Transport: &http.Transport{
+			TLSClientConfig: opts.TLSConfig,
+		},
+	}
+}