108 lines
3.0 KiB
Go
108 lines
3.0 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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"errors"
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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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"os"
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"os/signal"
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"runtime"
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"strconv"
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"sync/atomic"
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)
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// This is a count of the number of interrupts the process has received.
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// This is updated with sync/atomic whenever a SIGINT is received and can
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// be checked by the plugin safely to take action.
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var Interrupts int32 = 0
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const MagicCookieKey = "PACKER_PLUGIN_MAGIC_COOKIE"
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const MagicCookieValue = "d602bf8f470bc67ca7faa0386276bbdd4330efaf76d1a219cb4d6991ca9872b2"
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// The APIVersion is outputted along with the RPC address. The plugin
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// client validates this API version and will show an error if it doesn't
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// know how to speak it.
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const APIVersion = "1"
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// Server waits for a connection to this plugin and returns a Packer
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// RPC server that you can use to register components and serve them.
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func Server() (*packrpc.Server, error) {
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log.Printf("Plugin build against Packer '%s'", packer.GitCommit)
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if os.Getenv(MagicCookieKey) != MagicCookieValue {
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return nil, errors.New(
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"Please do not execute plugins directly. Packer will execute these for you.")
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}
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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 nil, err
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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 nil, err
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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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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("127.0.0.1:%d", port)
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listener, err = net.Listen("tcp", address)
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if err != nil {
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err = nil
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continue
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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.Printf("%s|%s\n", APIVersion, 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 nil, err
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}
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// Eat the interrupts
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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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var count int32 = 0
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for {
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<-ch
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newCount := atomic.AddInt32(&count, 1)
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log.Printf("Received interrupt signal (count: %d). Ignoring.", newCount)
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}
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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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return packrpc.NewServer(conn), nil
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}
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