terraform/rpc/server.go

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package rpc
import (
"io"
"log"
"net"
"net/rpc"
"github.com/hashicorp/terraform/terraform"
"github.com/hashicorp/yamux"
)
// Server listens for network connections and then dispenses interface
// implementations for Terraform over net/rpc.
type Server struct {
ProviderFunc ProviderFunc
ProvisionerFunc ProvisionerFunc
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}
// ProviderFunc creates terraform.ResourceProviders when they're requested
// from the server.
type ProviderFunc func() terraform.ResourceProvider
// ProvisionerFunc creates terraform.ResourceProvisioners when they're requested
// from the server.
type ProvisionerFunc func() terraform.ResourceProvisioner
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// Accept accepts connections on a listener and serves requests for
// each incoming connection. Accept blocks; the caller typically invokes
// it in a go statement.
func (s *Server) Accept(lis net.Listener) {
for {
conn, err := lis.Accept()
if err != nil {
log.Printf("[ERR] plugin server: %s", err)
return
}
go s.ServeConn(conn)
}
}
// ServeConn runs a single connection.
//
// ServeConn blocks, serving the connection until the client hangs up.
func (s *Server) ServeConn(conn io.ReadWriteCloser) {
// First create the yamux server to wrap this connection
mux, err := yamux.Server(conn, nil)
if err != nil {
conn.Close()
log.Printf("[ERR] plugin: %s", err)
return
}
// Accept the control connection
control, err := mux.Accept()
if err != nil {
mux.Close()
log.Printf("[ERR] plugin: %s", err)
return
}
// Create the broker and start it up
broker := newMuxBroker(mux)
go broker.Run()
// Use the control connection to build the dispenser and serve the
// connection.
server := rpc.NewServer()
server.RegisterName("Dispenser", &dispenseServer{
ProviderFunc: s.ProviderFunc,
ProvisionerFunc: s.ProvisionerFunc,
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broker: broker,
})
server.ServeConn(control)
}
// dispenseServer dispenses variousinterface implementations for Terraform.
type dispenseServer struct {
ProviderFunc ProviderFunc
ProvisionerFunc ProvisionerFunc
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broker *muxBroker
}
func (d *dispenseServer) ResourceProvider(
args interface{}, response *uint32) error {
id := d.broker.NextId()
*response = id
go func() {
conn, err := d.broker.Accept(id)
if err != nil {
log.Printf("[ERR] Plugin dispense: %s", err)
return
}
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serve(conn, "ResourceProvider", &ResourceProviderServer{
Broker: d.broker,
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Provider: d.ProviderFunc(),
})
}()
return nil
}
func (d *dispenseServer) ResourceProvisioner(
args interface{}, response *uint32) error {
id := d.broker.NextId()
*response = id
go func() {
conn, err := d.broker.Accept(id)
if err != nil {
log.Printf("[ERR] Plugin dispense: %s", err)
return
}
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serve(conn, "ResourceProvisioner", &ResourceProvisionerServer{
Provisioner: d.ProvisionerFunc(),
})
}()
return nil
}
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func acceptAndServe(mux *muxBroker, id uint32, n string, v interface{}) {
conn, err := mux.Accept(id)
if err != nil {
log.Printf("[ERR] Plugin acceptAndServe: %s", err)
return
}
serve(conn, n, v)
}
func serve(conn io.ReadWriteCloser, name string, v interface{}) {
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server := rpc.NewServer()
if err := server.RegisterName(name, v); err != nil {
log.Printf("[ERR] Plugin dispense: %s", err)
return
}
server.ServeConn(conn)
}