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package plugin
import (
"bytes"
"crypto/tls"
"encoding/json"
"fmt"
"io"
"net"
"google.golang.org/grpc"
"google.golang.org/grpc/credentials"
"google.golang.org/grpc/health"
"google.golang.org/grpc/health/grpc_health_v1"
)
// GRPCServiceName is the name of the service that the health check should
// return as passing.
const GRPCServiceName = "plugin"
// DefaultGRPCServer can be used with the "GRPCServer" field for Server
// as a default factory method to create a gRPC server with no extra options.
func DefaultGRPCServer(opts []grpc.ServerOption) *grpc.Server {
return grpc.NewServer(opts...)
}
// GRPCServer is a ServerType implementation that serves plugins over
// gRPC. This allows plugins to easily be written for other languages.
//
// The GRPCServer outputs a custom configuration as a base64-encoded
// JSON structure represented by the GRPCServerConfig config structure.
type GRPCServer struct {
// Plugins are the list of plugins to serve.
Plugins map[string]Plugin
// Server is the actual server that will accept connections. This
// will be used for plugin registration as well.
Server func([]grpc.ServerOption) *grpc.Server
// TLS should be the TLS configuration if available. If this is nil,
// the connection will not have transport security.
TLS *tls.Config
// DoneCh is the channel that is closed when this server has exited.
DoneCh chan struct{}
// Stdout/StderrLis are the readers for stdout/stderr that will be copied
// to the stdout/stderr connection that is output.
Stdout io.Reader
Stderr io.Reader
config GRPCServerConfig
server *grpc.Server
}
// ServerProtocol impl.
func (s *GRPCServer) Init() error {
// Create our server
var opts []grpc.ServerOption
if s.TLS != nil {
opts = append(opts, grpc.Creds(credentials.NewTLS(s.TLS)))
}
s.server = s.Server(opts)
// Register the health service
healthCheck := health.NewServer()
healthCheck.SetServingStatus(
GRPCServiceName, grpc_health_v1.HealthCheckResponse_SERVING)
grpc_health_v1.RegisterHealthServer(s.server, healthCheck)
// Register all our plugins onto the gRPC server.
for k, raw := range s.Plugins {
p, ok := raw.(GRPCPlugin)
if !ok {
return fmt.Errorf("%q is not a GRPC-compatibile plugin", k)
}
if err := p.GRPCServer(s.server); err != nil {
return fmt.Errorf("error registring %q: %s", k, err)
}
}
return nil
}
// Config is the GRPCServerConfig encoded as JSON then base64.
func (s *GRPCServer) Config() string {
// Create a buffer that will contain our final contents
var buf bytes.Buffer
// Wrap the base64 encoding with JSON encoding.
if err := json.NewEncoder(&buf).Encode(s.config); err != nil {
// We panic since ths shouldn't happen under any scenario. We
// carefully control the structure being encoded here and it should
// always be successful.
panic(err)
}
return buf.String()
}
func (s *GRPCServer) Serve(lis net.Listener) {
// Start serving in a goroutine
go s.server.Serve(lis)
// Wait until graceful completion
<-s.DoneCh
}
// GRPCServerConfig is the extra configuration passed along for consumers
// to facilitate using GRPC plugins.
type GRPCServerConfig struct {
StdoutAddr string `json:"stdout_addr"`
StderrAddr string `json:"stderr_addr"`
}
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