mirror of https://github.com/docker/cli.git
78 lines
1.8 KiB
Go
78 lines
1.8 KiB
Go
|
package socket
|
||
|
|
|
||
|
|
import (
|
||
|
|
"errors"
|
||
|
|
"io"
|
||
|
|
"net"
|
||
|
|
"os"
|
||
|
|
|
||
|
|
"github.com/docker/distribution/uuid"
|
||
|
|
)
|
||
|
|
|
||
|
|
// EnvKey represents the well-known environment variable used to pass the plugin being
|
||
|
|
// executed the socket name it should listen on to coordinate with the host CLI.
|
||
|
|
const EnvKey = "DOCKER_CLI_PLUGIN_SOCKET"
|
||
|
|
|
||
|
|
// SetupConn sets up a Unix socket listener, establishes a goroutine to handle connections
|
||
|
|
// and update the conn pointer, and returns the environment variable to pass to the plugin.
|
||
|
|
func SetupConn(conn **net.UnixConn) (string, error) {
|
||
|
|
listener, err := listen()
|
||
|
|
if err != nil {
|
||
|
|
return "", err
|
||
|
|
}
|
||
|
|
|
||
|
|
accept(listener, conn)
|
||
|
|
|
||
|
|
return EnvKey + "=" + listener.Addr().String(), nil
|
||
|
|
}
|
||
|
|
|
||
|
|
func listen() (*net.UnixListener, error) {
|
||
|
|
return net.ListenUnix("unix", &net.UnixAddr{
|
||
|
|
Name: "@docker_cli_" + uuid.Generate().String(),
|
||
|
|
Net: "unix",
|
||
|
|
})
|
||
|
|
}
|
||
|
|
|
||
|
|
func accept(listener *net.UnixListener, conn **net.UnixConn) {
|
||
|
|
defer listener.Close()
|
||
|
|
|
||
|
|
go func() {
|
||
|
|
for {
|
||
|
|
// ignore error here, if we failed to accept a connection,
|
||
|
|
// conn is nil and we fallback to previous behavior
|
||
|
|
*conn, _ = listener.AcceptUnix()
|
||
|
|
}
|
||
|
|
}()
|
||
|
|
}
|
||
|
|
|
||
|
|
// ConnectAndWait connects to the socket passed via well-known env var,
|
||
|
|
// if present, and attempts to read from it until it receives an EOF, at which
|
||
|
|
// point cb is called.
|
||
|
|
func ConnectAndWait(cb func()) {
|
||
|
|
socketAddr, ok := os.LookupEnv(EnvKey)
|
||
|
|
if !ok {
|
||
|
|
// if a plugin compiled against a more recent version of docker/cli
|
||
|
|
// is executed by an older CLI binary, ignore missing environment
|
||
|
|
// variable and behave as usual
|
||
|
|
return
|
||
|
|
}
|
||
|
|
addr, err := net.ResolveUnixAddr("unix", socketAddr)
|
||
|
|
if err != nil {
|
||
|
|
return
|
||
|
|
}
|
||
|
|
conn, err := net.DialUnix("unix", nil, addr)
|
||
|
|
if err != nil {
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
go func() {
|
||
|
|
b := make([]byte, 1)
|
||
|
|
for {
|
||
|
|
_, err := conn.Read(b)
|
||
|
|
if errors.Is(err, io.EOF) {
|
||
|
|
cb()
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}()
|
||
|
|
}
|