[WIP] Refactor podman system connection

* Add support to manage multiple connections
  * Add connection
  * Remove connection
  * Rename connection
  * Set connection as default
  * Add markdown/man pages
* Fix recursion in hack/xref-helpmsgs-manpages

Signed-off-by: Jhon Honce <jhonce@redhat.com>

1 files changed, 223 insertions, 0 deletions

diff --git a/cmd/podman/system/connection/add.go b/cmd/podman/system/connection/add.go
new file mode 100644
index 000000000..7522eb190
--- /dev/null
+++ b/cmd/podman/system/connection/add.go
@@ -0,0 +1,223 @@
+package connection
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"net"
+	"net/url"
+	"os"
+	"os/user"
+	"regexp"
+
+	"github.com/containers/common/pkg/config"
+	"github.com/containers/libpod/v2/cmd/podman/registry"
+	"github.com/containers/libpod/v2/cmd/podman/system"
+	"github.com/containers/libpod/v2/libpod/define"
+	"github.com/containers/libpod/v2/pkg/domain/entities"
+	"github.com/containers/libpod/v2/pkg/terminal"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+	"github.com/spf13/cobra"
+	"golang.org/x/crypto/ssh"
+	"golang.org/x/crypto/ssh/agent"
+)
+
+const schemaPattern = "^[A-Za-z][A-Za-z0-9+.-]*:"
+
+var (
+	addCmd = &cobra.Command{
+		Use:   "add [flags] NAME DESTINATION",
+		Args:  cobra.ExactArgs(2),
+		Short: "Record destination for the Podman service",
+		Long: `Add destination to podman configuration.
+  "destination" is of the form [user@]hostname or
+  an URI of the form ssh://[user@]hostname[:port]
+`,
+		RunE: add,
+		Example: `podman system connection add laptop server.fubar.com
+  podman system connection add --identity ~/.ssh/dev_rsa testing ssh://root@server.fubar.com:2222
+  podman system connection add --identity ~/.ssh/dev_rsa --port 22 production root@server.fubar.com
+  `,
+	}
+
+	cOpts = struct {
+		Identity string
+		Port     int
+		UDSPath  string
+		Default  bool
+	}{}
+)
+
+func init() {
+	registry.Commands = append(registry.Commands, registry.CliCommand{
+		Mode:    []entities.EngineMode{entities.ABIMode, entities.TunnelMode},
+		Command: addCmd,
+		Parent:  system.ConnectionCmd,
+	})
+
+	flags := addCmd.Flags()
+	flags.IntVarP(&cOpts.Port, "port", "p", 22, "SSH port number for destination")
+	flags.StringVar(&cOpts.Identity, "identity", "", "path to SSH identity file")
+	flags.StringVar(&cOpts.UDSPath, "socket-path", "", "path to podman socket on remote host. (default '/run/podman/podman.sock' or '/run/user/{uid}/podman/podman.sock)")
+	flags.BoolVarP(&cOpts.Default, "default", "d", false, "Set connection to be default")
+}
+
+func add(cmd *cobra.Command, args []string) error {
+	// Default to ssh: schema if none given
+	dest := args[1]
+	if match, err := regexp.Match(schemaPattern, []byte(dest)); err != nil {
+		return errors.Wrapf(err, "internal regex error %q", schemaPattern)
+	} else if !match {
+		dest = "ssh://" + dest
+	}
+
+	uri, err := url.Parse(dest)
+	if err != nil {
+		return errors.Wrapf(err, "failed to parse %q", dest)
+	}
+
+	if uri.User.Username() == "" {
+		if uri.User, err = getUserInfo(uri); err != nil {
+			return err
+		}
+	}
+
+	if cmd.Flags().Changed("socket-path") {
+		uri.Path = cmd.Flag("socket-path").Value.String()
+	}
+
+	if cmd.Flags().Changed("port") {
+		uri.Host = net.JoinHostPort(uri.Hostname(), cmd.Flag("port").Value.String())
+	}
+
+	if uri.Port() == "" {
+		uri.Host = net.JoinHostPort(uri.Hostname(), cmd.Flag("port").DefValue)
+	}
+
+	if uri.Path == "" {
+		if uri.Path, err = getUDS(cmd, uri); err != nil {
+			return errors.Wrapf(err, "failed to connect to  %q", uri.String())
+		}
+	}
+
+	cfg, err := config.ReadCustomConfig()
+	if err != nil {
+		return err
+	}
+
+	if cmd.Flags().Changed("default") {
+		if cOpts.Default {
+			cfg.Engine.ActiveService = args[0]
+		}
+	}
+
+	dst := config.Destination{
+		URI: uri.String(),
+	}
+
+	if cmd.Flags().Changed("identity") {
+		dst.Identity = cOpts.Identity
+	}
+
+	if cfg.Engine.ServiceDestinations == nil {
+		cfg.Engine.ServiceDestinations = map[string]config.Destination{
+			args[0]: dst,
+		}
+	} else {
+		cfg.Engine.ServiceDestinations[args[0]] = dst
+	}
+	return cfg.Write()
+}
+
+func getUserInfo(uri *url.URL) (*url.Userinfo, error) {
+	var (
+		usr *user.User
+		err error
+	)
+	if u, found := os.LookupEnv("_CONTAINERS_ROOTLESS_UID"); found {
+		usr, err = user.LookupId(u)
+		if err != nil {
+			return nil, errors.Wrapf(err, "failed to find user %q", u)
+		}
+	} else {
+		usr, err = user.Current()
+		if err != nil {
+			return nil, errors.Wrapf(err, "failed to obtain current user")
+		}
+	}
+
+	pw, set := uri.User.Password()
+	if set {
+		return url.UserPassword(usr.Username, pw), nil
+	}
+	return url.User(usr.Username), nil
+}
+
+func getUDS(cmd *cobra.Command, uri *url.URL) (string, error) {
+	var authMethods []ssh.AuthMethod
+	passwd, set := uri.User.Password()
+	if set {
+		authMethods = append(authMethods, ssh.Password(passwd))
+	}
+
+	if cmd.Flags().Changed("identity") {
+		value := cmd.Flag("identity").Value.String()
+		auth, err := terminal.PublicKey(value, []byte(passwd))
+		if err != nil {
+			return "", errors.Wrapf(err, "Failed to read identity %q", value)
+		}
+		authMethods = append(authMethods, auth)
+	}
+
+	if sock, found := os.LookupEnv("SSH_AUTH_SOCK"); found {
+		logrus.Debugf("Found SSH_AUTH_SOCK %q, ssh-agent signer enabled", sock)
+
+		c, err := net.Dial("unix", sock)
+		if err != nil {
+			return "", err
+		}
+		a := agent.NewClient(c)
+		authMethods = append(authMethods, ssh.PublicKeysCallback(a.Signers))
+	}
+
+	config := &ssh.ClientConfig{
+		User:            uri.User.Username(),
+		Auth:            authMethods,
+		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
+	}
+	dial, err := ssh.Dial("tcp", uri.Host, config)
+	if err != nil {
+		return "", errors.Wrapf(err, "failed to connect to %q", uri.Host)
+	}
+	defer dial.Close()
+
+	session, err := dial.NewSession()
+	if err != nil {
+		return "", errors.Wrapf(err, "failed to create new ssh session on %q", uri.Host)
+	}
+	defer session.Close()
+
+	// Override podman binary for testing etc
+	podman := "podman"
+	if v, found := os.LookupEnv("PODMAN_BINARY"); found {
+		podman = v
+	}
+	run := podman + " info --format=json"
+
+	var buffer bytes.Buffer
+	session.Stdout = &buffer
+	if err := session.Run(run); err != nil {
+		return "", errors.Wrapf(err, "failed to run %q", run)
+	}
+
+	var info define.Info
+	if err := json.Unmarshal(buffer.Bytes(), &info); err != nil {
+		return "", errors.Wrapf(err, "failed to parse 'podman info' results")
+	}
+
+	if info.Host.RemoteSocket == nil || len(info.Host.RemoteSocket.Path) == 0 {
+		return "", fmt.Errorf("remote podman %q failed to report its UDS socket", uri.Host)
+	}
+	return info.Host.RemoteSocket.Path, nil
+}