terraform/plugin/server.go

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package plugin
import (
"errors"
"fmt"
"io/ioutil"
"log"
"net"
"net/rpc"
"os"
"os/signal"
"runtime"
"strconv"
"sync/atomic"
tfrpc "github.com/hashicorp/terraform/rpc"
)
// The APIVersion is outputted along with the RPC address. The plugin
// client validates this API version and will show an error if it doesn't
// know how to speak it.
const APIVersion = "1"
// The "magic cookie" is used to verify that the user intended to
// actually run this binary. If this cookie isn't present as an
// environmental variable, then we bail out early with an error.
const MagicCookieKey = "TF_PLUGIN_MAGIC_COOKIE"
const MagicCookieValue = "d602bf8f470bc67ca7faa0386276bbdd4330efaf76d1a219cb4d6991ca9872b2"
func Serve(svc interface{}) error {
// First check the cookie
if os.Getenv(MagicCookieKey) != MagicCookieValue {
fmt.Fprintf(os.Stderr,
"This binary is a Terraform plugin. These are not meant to be\n" +
"executed directly. Please execute `terraform`, which will load\n" +
"any plugins automatically.\n")
os.Exit(1)
}
// Create the server to serve our interface
server := rpc.NewServer()
// Register the service
name, err := tfrpc.Register(server, svc)
if err != nil {
return err
}
// Register a listener so we can accept a connection
listener, err := serverListener()
if err != nil {
return err
}
defer listener.Close()
// Output the address and service name to stdout
log.Printf("Plugin address: %s %s\n",
listener.Addr().Network(), listener.Addr().String())
fmt.Printf("%s|%s|%s|%s\n",
APIVersion,
listener.Addr().Network(),
listener.Addr().String(),
name)
os.Stdout.Sync()
// Accept a connection
log.Println("Waiting for connection...")
conn, err := listener.Accept()
if err != nil {
log.Printf("Error accepting connection: %s\n", err.Error())
return err
}
// 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)
log.Printf(
"Received interrupt signal (count: %d). Ignoring.",
newCount)
}
}()
// Serve a single connection
log.Println("Serving a plugin connection...")
server.ServeConn(conn)
return nil
}
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("TF_PLUGIN_MIN_PORT"), 10, 32)
if err != nil {
return nil, err
}
maxPort, err := strconv.ParseInt(os.Getenv("TF_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("", "tf-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
}
return net.Listen("unix", path)
}