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// +build linux
package main
import (
"bytes"
"fmt"
"net"
"path/filepath"
"github.com/opencontainers/runtime-spec/specs-go"
"github.com/sirupsen/logrus"
"github.com/urfave/cli"
)
type notifySocket struct {
socket *net.UnixConn
host string
socketPath string
}
func newNotifySocket(context *cli.Context, notifySocketHost string, id string) *notifySocket {
if notifySocketHost == "" {
return nil
}
root := filepath.Join(context.GlobalString("root"), id)
path := filepath.Join(root, "notify.sock")
notifySocket := &notifySocket{
socket: nil,
host: notifySocketHost,
socketPath: path,
}
return notifySocket
}
func (ns *notifySocket) Close() error {
return ns.socket.Close()
}
// If systemd is supporting sd_notify protocol, this function will add support
// for sd_notify protocol from within the container.
func (s *notifySocket) setupSpec(context *cli.Context, spec *specs.Spec) {
mount := specs.Mount{Destination: s.host, Source: s.socketPath, Options: []string{"bind"}}
spec.Mounts = append(spec.Mounts, mount)
spec.Process.Env = append(spec.Process.Env, fmt.Sprintf("NOTIFY_SOCKET=%s", s.host))
}
func (s *notifySocket) setupSocket() error {
addr := net.UnixAddr{
Name: s.socketPath,
Net: "unixgram",
}
socket, err := net.ListenUnixgram("unixgram", &addr)
if err != nil {
return err
}
s.socket = socket
return nil
}
// pid1 must be set only with -d, as it is used to set the new process as the main process
// for the service in systemd
func (notifySocket *notifySocket) run(pid1 int) {
buf := make([]byte, 512)
notifySocketHostAddr := net.UnixAddr{Name: notifySocket.host, Net: "unixgram"}
client, err := net.DialUnix("unixgram", nil, &notifySocketHostAddr)
if err != nil {
logrus.Error(err)
return
}
for {
r, err := notifySocket.socket.Read(buf)
if err != nil {
break
}
var out bytes.Buffer
for _, line := range bytes.Split(buf[0:r], []byte{'\n'}) {
if bytes.HasPrefix(line, []byte("READY=")) {
_, err = out.Write(line)
if err != nil {
return
}
_, err = out.Write([]byte{'\n'})
if err != nil {
return
}
_, err = client.Write(out.Bytes())
if err != nil {
return
}
// now we can inform systemd to use pid1 as the pid to monitor
if pid1 > 0 {
newPid := fmt.Sprintf("MAINPID=%d\n", pid1)
client.Write([]byte(newPid))
}
return
}
}
}
}