mirror of
https://github.com/letic/terraform-provider-google.git
synced 2024-09-07 09:36:44 +00:00
223 lines
5.7 KiB
Go
223 lines
5.7 KiB
Go
package plugin
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import (
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"errors"
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"fmt"
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"io/ioutil"
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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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// CoreProtocolVersion is the ProtocolVersion of the plugin system itself.
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// We will increment this whenever we change any protocol behavior. This
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// will invalidate any prior plugins but will at least allow us to iterate
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// on the core in a safe way. We will do our best to do this very
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// infrequently.
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const CoreProtocolVersion = 1
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// HandshakeConfig is the configuration used by client and servers to
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// handshake before starting a plugin connection. This is embedded by
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// both ServeConfig and ClientConfig.
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//
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// In practice, the plugin host creates a HandshakeConfig that is exported
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// and plugins then can easily consume it.
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type HandshakeConfig struct {
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// ProtocolVersion is the version that clients must match on to
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// agree they can communicate. This should match the ProtocolVersion
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// set on ClientConfig when using a plugin.
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ProtocolVersion uint
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// MagicCookieKey and value are used as a very basic verification
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// that a plugin is intended to be launched. This is not a security
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// measure, just a UX feature. If the magic cookie doesn't match,
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// we show human-friendly output.
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MagicCookieKey string
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MagicCookieValue string
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}
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// ServeConfig configures what sorts of plugins are served.
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type ServeConfig struct {
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// HandshakeConfig is the configuration that must match clients.
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HandshakeConfig
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// Plugins are the plugins that are served.
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Plugins map[string]Plugin
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}
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// Serve serves the plugins given by ServeConfig.
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//
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// Serve doesn't return until the plugin is done being executed. Any
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// errors will be outputted to the log.
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//
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// This is the method that plugins should call in their main() functions.
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func Serve(opts *ServeConfig) {
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// Validate the handshake config
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if opts.MagicCookieKey == "" || opts.MagicCookieValue == "" {
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fmt.Fprintf(os.Stderr,
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"Misconfigured ServeConfig given to serve this plugin: no magic cookie\n"+
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"key or value was set. Please notify the plugin author and report\n"+
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"this as a bug.\n")
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os.Exit(1)
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}
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// First check the cookie
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if os.Getenv(opts.MagicCookieKey) != opts.MagicCookieValue {
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fmt.Fprintf(os.Stderr,
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"This binary is a plugin. These are not meant to be executed directly.\n"+
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"Please execute the program that consumes these plugins, which will\n"+
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"load any plugins automatically\n")
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os.Exit(1)
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}
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// Logging goes to the original stderr
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log.SetOutput(os.Stderr)
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// Create our new stdout, stderr files. These will override our built-in
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// stdout/stderr so that it works across the stream boundary.
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stdout_r, stdout_w, err := os.Pipe()
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if err != nil {
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fmt.Fprintf(os.Stderr, "Error preparing plugin: %s\n", err)
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os.Exit(1)
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}
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stderr_r, stderr_w, err := os.Pipe()
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if err != nil {
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fmt.Fprintf(os.Stderr, "Error preparing plugin: %s\n", err)
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os.Exit(1)
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}
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// Register a listener so we can accept a connection
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listener, err := serverListener()
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if err != nil {
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log.Printf("[ERR] plugin: plugin init: %s", err)
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return
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}
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defer listener.Close()
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// Create the channel to tell us when we're done
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doneCh := make(chan struct{})
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// Create the RPC server to dispense
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server := &RPCServer{
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Plugins: opts.Plugins,
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Stdout: stdout_r,
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Stderr: stderr_r,
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DoneCh: doneCh,
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}
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// Output the address and service name to stdout so that core can bring it up.
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log.Printf("[DEBUG] plugin: plugin address: %s %s\n",
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listener.Addr().Network(), listener.Addr().String())
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fmt.Printf("%d|%d|%s|%s\n",
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CoreProtocolVersion,
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opts.ProtocolVersion,
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listener.Addr().Network(),
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listener.Addr().String())
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os.Stdout.Sync()
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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(
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"[DEBUG] plugin: received interrupt signal (count: %d). Ignoring.",
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newCount)
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}
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}()
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// Set our new out, err
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os.Stdout = stdout_w
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os.Stderr = stderr_w
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// Serve
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go server.Accept(listener)
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// Wait for the graceful exit
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<-doneCh
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}
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func serverListener() (net.Listener, error) {
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if runtime.GOOS == "windows" {
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return serverListener_tcp()
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}
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return serverListener_unix()
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}
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func serverListener_tcp() (net.Listener, error) {
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minPort, err := strconv.ParseInt(os.Getenv("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("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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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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return listener, nil
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}
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}
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return nil, errors.New("Couldn't bind plugin TCP listener")
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}
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func serverListener_unix() (net.Listener, error) {
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tf, err := ioutil.TempFile("", "plugin")
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if err != nil {
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return nil, err
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}
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path := tf.Name()
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// Close the file and remove it because it has to not exist for
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// the domain socket.
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if err := tf.Close(); err != nil {
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return nil, err
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}
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if err := os.Remove(path); err != nil {
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return nil, err
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}
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l, err := net.Listen("unix", path)
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if err != nil {
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return nil, err
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}
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// Wrap the listener in rmListener so that the Unix domain socket file
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// is removed on close.
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return &rmListener{
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Listener: l,
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Path: path,
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}, nil
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}
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// rmListener is an implementation of net.Listener that forwards most
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// calls to the listener but also removes a file as part of the close. We
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// use this to cleanup the unix domain socket on close.
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type rmListener struct {
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net.Listener
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Path string
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}
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func (l *rmListener) Close() error {
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// Close the listener itself
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if err := l.Listener.Close(); err != nil {
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return err
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}
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// Remove the file
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return os.Remove(l.Path)
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}
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