mirror of https://github.com/docker/cli.git
113 lines
3.7 KiB
Go
113 lines
3.7 KiB
Go
// Package connhelper provides helpers for connecting to a remote daemon host with custom logic.
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package connhelper
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import (
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"context"
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"net"
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"net/url"
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"os"
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"strings"
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"github.com/docker/cli/cli/connhelper/commandconn"
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"github.com/docker/cli/cli/connhelper/ssh"
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"github.com/pkg/errors"
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)
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const (
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// DockerSSHRemoteBinaryEnv is the environment variable that can be used to
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// override the default Docker binary called over SSH
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DockerSSHRemoteBinaryEnv = "DOCKER_SSH_REMOTE_BINARY"
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)
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// ConnectionHelper allows to connect to a remote host with custom stream provider binary.
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type ConnectionHelper struct {
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Dialer func(ctx context.Context, network, addr string) (net.Conn, error)
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Host string // dummy URL used for HTTP requests. e.g. "http://docker"
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}
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// GetConnectionHelper returns Docker-specific connection helper for the given URL.
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// GetConnectionHelper returns nil without error when no helper is registered for the scheme.
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//
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// ssh://<user>@<host> URL requires Docker 18.09 or later on the remote host.
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func GetConnectionHelper(daemonURL string) (*ConnectionHelper, error) {
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return getConnectionHelper(daemonURL, nil)
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}
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// GetConnectionHelperWithSSHOpts returns Docker-specific connection helper for
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// the given URL, and accepts additional options for ssh connections. It returns
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// nil without error when no helper is registered for the scheme.
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//
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// Requires Docker 18.09 or later on the remote host.
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func GetConnectionHelperWithSSHOpts(daemonURL string, sshFlags []string) (*ConnectionHelper, error) {
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return getConnectionHelper(daemonURL, sshFlags)
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}
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func getConnectionHelper(daemonURL string, sshFlags []string) (*ConnectionHelper, error) {
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u, err := url.Parse(daemonURL)
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if err != nil {
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return nil, err
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}
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if u.Scheme == "ssh" {
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sp, err := ssh.ParseURL(daemonURL)
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if err != nil {
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return nil, errors.Wrap(err, "ssh host connection is not valid")
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}
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sshFlags = addSSHTimeout(sshFlags)
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sshFlags = disablePseudoTerminalAllocation(sshFlags)
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return &ConnectionHelper{
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Dialer: func(ctx context.Context, network, addr string) (net.Conn, error) {
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args := []string{dockerSSHRemoteBinary()}
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if sp.Path != "" {
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args = append(args, "--host", "unix://"+sp.Path)
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}
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args = append(args, "system", "dial-stdio")
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return commandconn.New(ctx, "ssh", append(sshFlags, sp.Args(args...)...)...)
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},
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Host: "http://docker.example.com",
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}, nil
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}
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// Future version may support plugins via ~/.docker/config.json. e.g. "dind"
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// See docker/cli#889 for the previous discussion.
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return nil, err
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}
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// GetCommandConnectionHelper returns Docker-specific connection helper constructed from an arbitrary command.
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func GetCommandConnectionHelper(cmd string, flags ...string) (*ConnectionHelper, error) {
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return &ConnectionHelper{
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Dialer: func(ctx context.Context, network, addr string) (net.Conn, error) {
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return commandconn.New(ctx, cmd, flags...)
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},
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Host: "http://docker.example.com",
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}, nil
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}
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func addSSHTimeout(sshFlags []string) []string {
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if !strings.Contains(strings.Join(sshFlags, ""), "ConnectTimeout") {
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sshFlags = append(sshFlags, "-o ConnectTimeout=30")
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}
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return sshFlags
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}
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// disablePseudoTerminalAllocation disables pseudo-terminal allocation to
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// prevent SSH from executing as a login shell
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func disablePseudoTerminalAllocation(sshFlags []string) []string {
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for _, flag := range sshFlags {
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if flag == "-T" {
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return sshFlags
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}
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}
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return append(sshFlags, "-T")
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}
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// dockerSSHRemoteBinary returns the binary to use when executing Docker
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// commands over SSH. It defaults to "docker" if the DOCKER_SSH_REMOTE_BINARY
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// environment variable is not set.
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func dockerSSHRemoteBinary() string {
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value := os.Getenv(DockerSSHRemoteBinaryEnv)
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if value == "" {
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return "docker"
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}
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return value
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}
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