DockerCLI/cli/connhelper/connhelper.go

82 lines
2.8 KiB
Go

// Package connhelper provides helpers for connecting to a remote daemon host with custom logic.
package connhelper
import (
"context"
"net"
"net/url"
"strings"
"github.com/docker/cli/cli/connhelper/commandconn"
"github.com/docker/cli/cli/connhelper/ssh"
"github.com/pkg/errors"
)
// ConnectionHelper allows to connect to a remote host with custom stream provider binary.
type ConnectionHelper struct {
Dialer func(ctx context.Context, network, addr string) (net.Conn, error)
Host string // dummy URL used for HTTP requests. e.g. "http://docker"
}
// GetConnectionHelper returns Docker-specific connection helper for the given URL.
// GetConnectionHelper returns nil without error when no helper is registered for the scheme.
//
// ssh://<user>@<host> URL requires Docker 18.09 or later on the remote host.
func GetConnectionHelper(daemonURL string) (*ConnectionHelper, error) {
return getConnectionHelper(daemonURL, nil)
}
// GetConnectionHelperWithSSHOpts returns Docker-specific connection helper for
// the given URL, and accepts additional options for ssh connections. It returns
// nil without error when no helper is registered for the scheme.
//
// Requires Docker 18.09 or later on the remote host.
func GetConnectionHelperWithSSHOpts(daemonURL string, sshFlags []string) (*ConnectionHelper, error) {
return getConnectionHelper(daemonURL, sshFlags)
}
func getConnectionHelper(daemonURL string, sshFlags []string) (*ConnectionHelper, error) {
u, err := url.Parse(daemonURL)
if err != nil {
return nil, err
}
if u.Scheme == "ssh" {
sp, err := ssh.ParseURL(daemonURL)
if err != nil {
return nil, errors.Wrap(err, "ssh host connection is not valid")
}
return &ConnectionHelper{
Dialer: func(ctx context.Context, network, addr string) (net.Conn, error) {
args := []string{"docker"}
if sp.Path != "" {
args = append(args, "--host", "unix://"+sp.Path)
}
sshFlags = addSSHTimeout(sshFlags)
args = append(args, "system", "dial-stdio")
return commandconn.New(ctx, "ssh", append(sshFlags, sp.Args(args...)...)...)
},
Host: "http://docker.example.com",
}, nil
}
// Future version may support plugins via ~/.docker/config.json. e.g. "dind"
// See docker/cli#889 for the previous discussion.
return nil, err
}
// GetCommandConnectionHelper returns Docker-specific connection helper constructed from an arbitrary command.
func GetCommandConnectionHelper(cmd string, flags ...string) (*ConnectionHelper, error) {
return &ConnectionHelper{
Dialer: func(ctx context.Context, network, addr string) (net.Conn, error) {
return commandconn.New(ctx, cmd, flags...)
},
Host: "http://docker.example.com",
}, nil
}
func addSSHTimeout(sshFlags []string) []string {
if !strings.Contains(strings.Join(sshFlags, ""), "ConnectTimeout") {
sshFlags = append(sshFlags, "-o ConnectTimeout=30")
}
return sshFlags
}