152 lines
3.5 KiB
Go
152 lines
3.5 KiB
Go
// The plugin package provides the functionality to both expose a Packer
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// plugin binary and to connect to an existing Packer plugin binary.
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//
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// Packer supports plugins in the form of self-contained external static
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// Go binaries. These binaries behave in a certain way (enforced by this
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// package) and are connected to in a certain way (also enforced by this
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// package).
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package plugin
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import (
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"fmt"
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"github.com/mitchellh/packer/packer"
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packrpc "github.com/mitchellh/packer/packer/rpc"
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"log"
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"net"
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"net/rpc"
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"os"
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"os/signal"
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"runtime"
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"strconv"
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"strings"
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)
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// This serves a single RPC connection on the given RPC server on
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// a random port.
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func serve(server *rpc.Server) (err error) {
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// If there is no explicit number of Go threads to use, then set it
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if os.Getenv("GOMAXPROCS") == "" {
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runtime.GOMAXPROCS(runtime.NumCPU())
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}
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minPort, err := strconv.ParseInt(os.Getenv("PACKER_PLUGIN_MIN_PORT"), 10, 32)
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if err != nil {
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return
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}
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maxPort, err := strconv.ParseInt(os.Getenv("PACKER_PLUGIN_MAX_PORT"), 10, 32)
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if err != nil {
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return
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}
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log.Printf("Plugin minimum port: %d\n", minPort)
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log.Printf("Plugin maximum port: %d\n", maxPort)
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// Set the RPC port range
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packrpc.PortRange(int(minPort), int(maxPort))
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var address string
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var listener net.Listener
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for port := minPort; port <= maxPort; port++ {
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address = fmt.Sprintf(":%d", port)
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listener, err = net.Listen("tcp", address)
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if err != nil {
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if !strings.Contains(err.Error(), "address already in use") {
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// Not an address already in use error, return.
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return
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} else {
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// Address is in use, just try another
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err = nil
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continue
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}
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}
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break
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}
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defer listener.Close()
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// Output the address to stdout
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log.Printf("Plugin address: %s\n", address)
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fmt.Println(address)
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os.Stdout.Sync()
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// Accept a connection
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log.Println("Waiting for connection...")
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conn, err := listener.Accept()
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if err != nil {
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log.Printf("Error accepting connection: %s\n", err.Error())
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return
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}
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// Serve a single connection
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log.Println("Serving a plugin connection...")
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server.ServeConn(conn)
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return
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}
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// Registers a signal handler to "swallow" interrupts so that the
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// plugin isn't killed. The main host Packer process is responsible
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// for killing the plugins when interrupted.
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func swallowInterrupts() {
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ch := make(chan os.Signal, 1)
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signal.Notify(ch, os.Interrupt)
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go func() {
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<-ch
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log.Println("Received interrupt signal. Ignoring.")
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}()
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}
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// Serves a builder from a plugin.
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func ServeBuilder(builder packer.Builder) {
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log.Println("Preparing to serve a builder plugin...")
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server := rpc.NewServer()
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packrpc.RegisterBuilder(server, builder)
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swallowInterrupts()
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if err := serve(server); err != nil {
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log.Panic(err)
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}
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}
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// Serves a command from a plugin.
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func ServeCommand(command packer.Command) {
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log.Println("Preparing to serve a command plugin...")
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server := rpc.NewServer()
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packrpc.RegisterCommand(server, command)
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swallowInterrupts()
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if err := serve(server); err != nil {
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log.Panic(err)
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}
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}
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// Serves a hook from a plugin.
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func ServeHook(hook packer.Hook) {
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log.Println("Preparing to serve a hook plugin...")
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server := rpc.NewServer()
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packrpc.RegisterHook(server, hook)
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swallowInterrupts()
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if err := serve(server); err != nil {
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log.Panic(err)
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}
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}
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// Serves a provisioner from a plugin.
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func ServeProvisioner(p packer.Provisioner) {
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log.Println("Preparing to serve a provisioner plugin...")
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server := rpc.NewServer()
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packrpc.RegisterProvisioner(server, p)
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swallowInterrupts()
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if err := serve(server); err != nil {
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log.Panic(err)
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}
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}
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