MM-10702 Moving plugins to use hashicorp go-plugin. (#8978)

* Moving plugins to use hashicorp go-plugin.

* Tweaks from feedback.

1 files changed, 317 insertions, 0 deletions

diff --git a/vendor/github.com/hashicorp/go-plugin/server.go b/vendor/github.com/hashicorp/go-plugin/server.go
new file mode 100644
index 000000000..1e808b99e
--- /dev/null
+++ b/vendor/github.com/hashicorp/go-plugin/server.go
@@ -0,0 +1,317 @@
+package plugin
+
+import (
+	"crypto/tls"
+	"encoding/base64"
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net"
+	"os"
+	"os/signal"
+	"runtime"
+	"strconv"
+	"sync/atomic"
+
+	"github.com/hashicorp/go-hclog"
+
+	"google.golang.org/grpc"
+)
+
+// CoreProtocolVersion is the ProtocolVersion of the plugin system itself.
+// We will increment this whenever we change any protocol behavior. This
+// will invalidate any prior plugins but will at least allow us to iterate
+// on the core in a safe way. We will do our best to do this very
+// infrequently.
+const CoreProtocolVersion = 1
+
+// HandshakeConfig is the configuration used by client and servers to
+// handshake before starting a plugin connection. This is embedded by
+// both ServeConfig and ClientConfig.
+//
+// In practice, the plugin host creates a HandshakeConfig that is exported
+// and plugins then can easily consume it.
+type HandshakeConfig struct {
+	// ProtocolVersion is the version that clients must match on to
+	// agree they can communicate. This should match the ProtocolVersion
+	// set on ClientConfig when using a plugin.
+	ProtocolVersion uint
+
+	// MagicCookieKey and value are used as a very basic verification
+	// that a plugin is intended to be launched. This is not a security
+	// measure, just a UX feature. If the magic cookie doesn't match,
+	// we show human-friendly output.
+	MagicCookieKey   string
+	MagicCookieValue string
+}
+
+// ServeConfig configures what sorts of plugins are served.
+type ServeConfig struct {
+	// HandshakeConfig is the configuration that must match clients.
+	HandshakeConfig
+
+	// TLSProvider is a function that returns a configured tls.Config.
+	TLSProvider func() (*tls.Config, error)
+
+	// Plugins are the plugins that are served.
+	Plugins map[string]Plugin
+
+	// GRPCServer should be non-nil to enable serving the plugins over
+	// gRPC. This is a function to create the server when needed with the
+	// given server options. The server options populated by go-plugin will
+	// be for TLS if set. You may modify the input slice.
+	//
+	// Note that the grpc.Server will automatically be registered with
+	// the gRPC health checking service. This is not optional since go-plugin
+	// relies on this to implement Ping().
+	GRPCServer func([]grpc.ServerOption) *grpc.Server
+
+	// Logger is used to pass a logger into the server. If none is provided the
+	// server will create a default logger.
+	Logger hclog.Logger
+}
+
+// Protocol returns the protocol that this server should speak.
+func (c *ServeConfig) Protocol() Protocol {
+	result := ProtocolNetRPC
+	if c.GRPCServer != nil {
+		result = ProtocolGRPC
+	}
+
+	return result
+}
+
+// Serve serves the plugins given by ServeConfig.
+//
+// Serve doesn't return until the plugin is done being executed. Any
+// errors will be outputted to os.Stderr.
+//
+// This is the method that plugins should call in their main() functions.
+func Serve(opts *ServeConfig) {
+	// Validate the handshake config
+	if opts.MagicCookieKey == "" || opts.MagicCookieValue == "" {
+		fmt.Fprintf(os.Stderr,
+			"Misconfigured ServeConfig given to serve this plugin: no magic cookie\n"+
+				"key or value was set. Please notify the plugin author and report\n"+
+				"this as a bug.\n")
+		os.Exit(1)
+	}
+
+	// First check the cookie
+	if os.Getenv(opts.MagicCookieKey) != opts.MagicCookieValue {
+		fmt.Fprintf(os.Stderr,
+			"This binary is a plugin. These are not meant to be executed directly.\n"+
+				"Please execute the program that consumes these plugins, which will\n"+
+				"load any plugins automatically\n")
+		os.Exit(1)
+	}
+
+	// Logging goes to the original stderr
+	log.SetOutput(os.Stderr)
+
+	logger := opts.Logger
+	if logger == nil {
+		// internal logger to os.Stderr
+		logger = hclog.New(&hclog.LoggerOptions{
+			Level:      hclog.Trace,
+			Output:     os.Stderr,
+			JSONFormat: true,
+		})
+	}
+
+	// Create our new stdout, stderr files. These will override our built-in
+	// stdout/stderr so that it works across the stream boundary.
+	stdout_r, stdout_w, err := os.Pipe()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error preparing plugin: %s\n", err)
+		os.Exit(1)
+	}
+	stderr_r, stderr_w, err := os.Pipe()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error preparing plugin: %s\n", err)
+		os.Exit(1)
+	}
+
+	// Register a listener so we can accept a connection
+	listener, err := serverListener()
+	if err != nil {
+		logger.Error("plugin init error", "error", err)
+		return
+	}
+
+	// Close the listener on return. We wrap this in a func() on purpose
+	// because the "listener" reference may change to TLS.
+	defer func() {
+		listener.Close()
+	}()
+
+	var tlsConfig *tls.Config
+	if opts.TLSProvider != nil {
+		tlsConfig, err = opts.TLSProvider()
+		if err != nil {
+			logger.Error("plugin tls init", "error", err)
+			return
+		}
+	}
+
+	// Create the channel to tell us when we're done
+	doneCh := make(chan struct{})
+
+	// Build the server type
+	var server ServerProtocol
+	switch opts.Protocol() {
+	case ProtocolNetRPC:
+		// If we have a TLS configuration then we wrap the listener
+		// ourselves and do it at that level.
+		if tlsConfig != nil {
+			listener = tls.NewListener(listener, tlsConfig)
+		}
+
+		// Create the RPC server to dispense
+		server = &RPCServer{
+			Plugins: opts.Plugins,
+			Stdout:  stdout_r,
+			Stderr:  stderr_r,
+			DoneCh:  doneCh,
+		}
+
+	case ProtocolGRPC:
+		// Create the gRPC server
+		server = &GRPCServer{
+			Plugins: opts.Plugins,
+			Server:  opts.GRPCServer,
+			TLS:     tlsConfig,
+			Stdout:  stdout_r,
+			Stderr:  stderr_r,
+			DoneCh:  doneCh,
+		}
+
+	default:
+		panic("unknown server protocol: " + opts.Protocol())
+	}
+
+	// Initialize the servers
+	if err := server.Init(); err != nil {
+		logger.Error("protocol init", "error", err)
+		return
+	}
+
+	// Build the extra configuration
+	extra := ""
+	if v := server.Config(); v != "" {
+		extra = base64.StdEncoding.EncodeToString([]byte(v))
+	}
+	if extra != "" {
+		extra = "|" + extra
+	}
+
+	logger.Debug("plugin address", "network", listener.Addr().Network(), "address", listener.Addr().String())
+
+	// Output the address and service name to stdout so that core can bring it up.
+	fmt.Printf("%d|%d|%s|%s|%s%s\n",
+		CoreProtocolVersion,
+		opts.ProtocolVersion,
+		listener.Addr().Network(),
+		listener.Addr().String(),
+		opts.Protocol(),
+		extra)
+	os.Stdout.Sync()
+
+	// Eat the interrupts
+	ch := make(chan os.Signal, 1)
+	signal.Notify(ch, os.Interrupt)
+	go func() {
+		var count int32 = 0
+		for {
+			<-ch
+			newCount := atomic.AddInt32(&count, 1)
+			logger.Debug("plugin received interrupt signal, ignoring", "count", newCount)
+		}
+	}()
+
+	// Set our new out, err
+	os.Stdout = stdout_w
+	os.Stderr = stderr_w
+
+	// Accept connections and wait for completion
+	go server.Serve(listener)
+	<-doneCh
+}
+
+func serverListener() (net.Listener, error) {
+	if runtime.GOOS == "windows" {
+		return serverListener_tcp()
+	}
+
+	return serverListener_unix()
+}
+
+func serverListener_tcp() (net.Listener, error) {
+	minPort, err := strconv.ParseInt(os.Getenv("PLUGIN_MIN_PORT"), 10, 32)
+	if err != nil {
+		return nil, err
+	}
+
+	maxPort, err := strconv.ParseInt(os.Getenv("PLUGIN_MAX_PORT"), 10, 32)
+	if err != nil {
+		return nil, err
+	}
+
+	for port := minPort; port <= maxPort; port++ {
+		address := fmt.Sprintf("127.0.0.1:%d", port)
+		listener, err := net.Listen("tcp", address)
+		if err == nil {
+			return listener, nil
+		}
+	}
+
+	return nil, errors.New("Couldn't bind plugin TCP listener")
+}
+
+func serverListener_unix() (net.Listener, error) {
+	tf, err := ioutil.TempFile("", "plugin")
+	if err != nil {
+		return nil, err
+	}
+	path := tf.Name()
+
+	// Close the file and remove it because it has to not exist for
+	// the domain socket.
+	if err := tf.Close(); err != nil {
+		return nil, err
+	}
+	if err := os.Remove(path); err != nil {
+		return nil, err
+	}
+
+	l, err := net.Listen("unix", path)
+	if err != nil {
+		return nil, err
+	}
+
+	// Wrap the listener in rmListener so that the Unix domain socket file
+	// is removed on close.
+	return &rmListener{
+		Listener: l,
+		Path:     path,
+	}, nil
+}
+
+// rmListener is an implementation of net.Listener that forwards most
+// calls to the listener but also removes a file as part of the close. We
+// use this to cleanup the unix domain socket on close.
+type rmListener struct {
+	net.Listener
+	Path string
+}
+
+func (l *rmListener) Close() error {
+	// Close the listener itself
+	if err := l.Listener.Close(); err != nil {
+		return err
+	}
+
+	// Remove the file
+	return os.Remove(l.Path)
+}