github.com/rita33cool1/iot-system-gateway@v0.0.0-20200911033302-e65bde238cc5/docker-engine/daemon/listeners/listeners_linux.go (about)

     1  package listeners // import "github.com/docker/docker/daemon/listeners"
     2  
     3  import (
     4  	"crypto/tls"
     5  	"fmt"
     6  	"net"
     7  	"os"
     8  	"strconv"
     9  
    10  	"github.com/coreos/go-systemd/activation"
    11  	"github.com/docker/go-connections/sockets"
    12  	"github.com/sirupsen/logrus"
    13  )
    14  
    15  // Init creates new listeners for the server.
    16  // TODO: Clean up the fact that socketGroup and tlsConfig aren't always used.
    17  func Init(proto, addr, socketGroup string, tlsConfig *tls.Config) ([]net.Listener, error) {
    18  	ls := []net.Listener{}
    19  
    20  	switch proto {
    21  	case "fd":
    22  		fds, err := listenFD(addr, tlsConfig)
    23  		if err != nil {
    24  			return nil, err
    25  		}
    26  		ls = append(ls, fds...)
    27  	case "tcp":
    28  		l, err := sockets.NewTCPSocket(addr, tlsConfig)
    29  		if err != nil {
    30  			return nil, err
    31  		}
    32  		ls = append(ls, l)
    33  	case "unix":
    34  		gid, err := lookupGID(socketGroup)
    35  		if err != nil {
    36  			if socketGroup != "" {
    37  				if socketGroup != defaultSocketGroup {
    38  					return nil, err
    39  				}
    40  				logrus.Warnf("could not change group %s to %s: %v", addr, defaultSocketGroup, err)
    41  			}
    42  			gid = os.Getgid()
    43  		}
    44  		l, err := sockets.NewUnixSocket(addr, gid)
    45  		if err != nil {
    46  			return nil, fmt.Errorf("can't create unix socket %s: %v", addr, err)
    47  		}
    48  		ls = append(ls, l)
    49  	default:
    50  		return nil, fmt.Errorf("invalid protocol format: %q", proto)
    51  	}
    52  
    53  	return ls, nil
    54  }
    55  
    56  // listenFD returns the specified socket activated files as a slice of
    57  // net.Listeners or all of the activated files if "*" is given.
    58  func listenFD(addr string, tlsConfig *tls.Config) ([]net.Listener, error) {
    59  	var (
    60  		err       error
    61  		listeners []net.Listener
    62  	)
    63  	// socket activation
    64  	if tlsConfig != nil {
    65  		listeners, err = activation.TLSListeners(false, tlsConfig)
    66  	} else {
    67  		listeners, err = activation.Listeners(false)
    68  	}
    69  	if err != nil {
    70  		return nil, err
    71  	}
    72  
    73  	if len(listeners) == 0 {
    74  		return nil, fmt.Errorf("no sockets found via socket activation: make sure the service was started by systemd")
    75  	}
    76  
    77  	// default to all fds just like unix:// and tcp://
    78  	if addr == "" || addr == "*" {
    79  		return listeners, nil
    80  	}
    81  
    82  	fdNum, err := strconv.Atoi(addr)
    83  	if err != nil {
    84  		return nil, fmt.Errorf("failed to parse systemd fd address: should be a number: %v", addr)
    85  	}
    86  	fdOffset := fdNum - 3
    87  	if len(listeners) < fdOffset+1 {
    88  		return nil, fmt.Errorf("too few socket activated files passed in by systemd")
    89  	}
    90  	if listeners[fdOffset] == nil {
    91  		return nil, fmt.Errorf("failed to listen on systemd activated file: fd %d", fdOffset+3)
    92  	}
    93  	for i, ls := range listeners {
    94  		if i == fdOffset || ls == nil {
    95  			continue
    96  		}
    97  		if err := ls.Close(); err != nil {
    98  			return nil, fmt.Errorf("failed to close systemd activated file: fd %d: %v", fdOffset+3, err)
    99  		}
   100  	}
   101  	return []net.Listener{listeners[fdOffset]}, nil
   102  }