consul/command/keys.go

package command

import (
	"encoding/base64"
	"encoding/json"
	"flag"
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"github.com/hashicorp/consul/command/agent"
	"github.com/mitchellh/cli"
	"github.com/ryanuber/columnize"
)

// KeysCommand is a Command implementation that handles querying, installing,
// and removing gossip encryption keys from a keyring.
type KeysCommand struct {
	Ui cli.Ui
}

func (c *KeysCommand) Run(args []string) int {
	var installKey, useKey, removeKey, init, dataDir string
	var listKeys bool

	cmdFlags := flag.NewFlagSet("keys", flag.ContinueOnError)
	cmdFlags.Usage = func() { c.Ui.Output(c.Help()) }

	cmdFlags.StringVar(&installKey, "install", "", "install key")
	cmdFlags.StringVar(&useKey, "use", "", "use key")
	cmdFlags.StringVar(&removeKey, "remove", "", "remove key")
	cmdFlags.BoolVar(&listKeys, "list", false, "list keys")
	cmdFlags.StringVar(&init, "init", "", "initialize keyring")
	cmdFlags.StringVar(&dataDir, "data-dir", "", "data directory")

	rpcAddr := RPCAddrFlag(cmdFlags)
	if err := cmdFlags.Parse(args); err != nil {
		return 1
	}

	c.Ui = &cli.PrefixedUi{
		OutputPrefix: "",
		InfoPrefix:   "==> ",
		ErrorPrefix:  "",
		Ui:           c.Ui,
	}

	// Only accept a single argument
	found := listKeys
	for _, arg := range []string{installKey, useKey, removeKey, init} {
		if found && len(arg) > 0 {
			c.Ui.Error("Only a single action is allowed")
			return 1
		}
		found = found || len(arg) > 0
	}

	// Fail fast if no actionable args were passed
	if !found {
		c.Ui.Error(c.Help())
		return 1
	}

	if init != "" {
		if dataDir == "" {
			c.Ui.Error("Must provide -data-dir")
			return 1
		}
		path := filepath.Join(dataDir, agent.SerfKeyring)
		if err := initializeKeyring(path, init); err != nil {
			c.Ui.Error(fmt.Sprintf("Error: %s", err))
			return 1
		}

		return 0
	}

	// All other operations will require a client connection
	client, err := RPCClient(*rpcAddr)
	if err != nil {
		c.Ui.Error(fmt.Sprintf("Error connecting to Consul agent: %s", err))
		return 1
	}
	defer client.Close()

	// For all key-related operations, we must be querying a server node.
	s, err := client.Stats()
	if err != nil {
		c.Ui.Error(fmt.Sprintf("Error: %s", err))
		return 1
	}
	if s["consul"]["server"] != "true" {
		c.Ui.Error("Error: Key modification can only be handled by a server")
		return 1
	}

	if listKeys {
		c.Ui.Info("Asking all WAN members for installed keys...")
		if rval := c.listKeysOperation(client.ListKeysWAN); rval != 0 {
			return rval
		}
		c.Ui.Info("Asking all LAN members for installed keys...")
		if rval := c.listKeysOperation(client.ListKeysLAN); rval != 0 {
			return rval
		}
		return 0
	}

	if installKey != "" {
		c.Ui.Info("Installing new WAN gossip encryption key...")
		if rval := c.keyOperation(installKey, client.InstallKeyWAN); rval != 0 {
			return rval
		}
		c.Ui.Info("Installing new LAN gossip encryption key...")
		if rval := c.keyOperation(installKey, client.InstallKeyLAN); rval != 0 {
			return rval
		}
		c.Ui.Info("Successfully installed key!")
		return 0
	}

	if useKey != "" {
		c.Ui.Info("Changing primary WAN gossip encryption key...")
		if rval := c.keyOperation(useKey, client.UseKeyWAN); rval != 0 {
			return rval
		}
		c.Ui.Info("Changing primary LAN gossip encryption key...")
		if rval := c.keyOperation(useKey, client.UseKeyLAN); rval != 0 {
			return rval
		}
		c.Ui.Info("Successfully changed primary key!")
		return 0
	}

	if removeKey != "" {
		c.Ui.Info("Removing WAN gossip encryption key...")
		if rval := c.keyOperation(removeKey, client.RemoveKeyWAN); rval != 0 {
			return rval
		}
		c.Ui.Info("Removing LAN gossip encryption key...")
		if rval := c.keyOperation(removeKey, client.RemoveKeyLAN); rval != 0 {
			return rval
		}
		c.Ui.Info("Successfully removed key!")
		return 0
	}

	// Should never make it here
	return 0
}

type keyFunc func(string) (map[string]string, error)

func (c *KeysCommand) keyOperation(key string, fn keyFunc) int {
	var out []string

	failures, err := fn(key)

	if err != nil {
		if len(failures) > 0 {
			for node, msg := range failures {
				out = append(out, fmt.Sprintf("failed: %s | %s", node, msg))
			}
			c.Ui.Error(columnize.SimpleFormat(out))
		}
		c.Ui.Error("")
		c.Ui.Error(fmt.Sprintf("Error: %s", err))
		return 1
	}

	return 0
}

type listKeysFunc func() (map[string]int, int, map[string]string, error)

func (c *KeysCommand) listKeysOperation(fn listKeysFunc) int {
	var out []string

	keys, numNodes, failures, err := fn()

	if err != nil {
		if len(failures) > 0 {
			for node, msg := range failures {
				out = append(out, fmt.Sprintf("failed: %s | %s", node, msg))
			}
			c.Ui.Error(columnize.SimpleFormat(out))
		}
		c.Ui.Error("")
		c.Ui.Error(fmt.Sprintf("Failed gathering member keys: %s", err))
		return 1
	}
	for key, num := range keys {
		out = append(out, fmt.Sprintf("%s | [%d/%d]", key, num, numNodes))
	}
	c.Ui.Output(columnize.SimpleFormat(out))

	c.Ui.Output("")
	return 0
}

// initializeKeyring will create a keyring file at a given path.
func initializeKeyring(path, key string) error {
	if _, err := base64.StdEncoding.DecodeString(key); err != nil {
		return fmt.Errorf("Invalid key: %s", err)
	}

	keys := []string{key}
	keyringBytes, err := json.MarshalIndent(keys, "", "  ")
	if err != nil {
		return err
	}

	if err := os.MkdirAll(filepath.Dir(path), 0700); err != nil {
		return err
	}

	if _, err := os.Stat(path); err == nil {
		return fmt.Errorf("File already exists: %s", path)
	}

	fh, err := os.OpenFile(path, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0600)
	if err != nil {
		return err
	}
	defer fh.Close()

	if _, err := fh.Write(keyringBytes); err != nil {
		os.Remove(path)
		return err
	}

	return nil
}

func (c *KeysCommand) Help() string {
	helpText := `
Usage: consul keys [options]

  Manages encryption keys used for gossip messages. Gossip encryption is
  optional. When enabled, this command may be used to examine active encryption
  keys in the cluster, add new keys, and remove old ones. When combined, this
  functionality provides the ability to perform key rotation cluster-wide,
  without disrupting the cluster.

Options:

  -install=<key>            Install a new encryption key. This will broadcast
                            the new key to all members in the cluster.
  -use=<key>                Change the primary encryption key, which is used to
                            encrypt messages. The key must already be installed
                            before this operation can succeed.
  -remove=<key>             Remove the given key from the cluster. This
                            operation may only be performed on keys which are
                            not currently the primary key.
  -list                     List all keys currently in use within the cluster.
  -wan                      If talking with a server node, this flag can be used
                            to operate on the WAN gossip layer.
  -init=<key>               Create an initial keyring file for Consul to use
                            containing the provided key. By default, this option
                            will only initialize the LAN keyring. If the -wan
                            option is also passed, then the wan keyring will be
                            created as well. The -data-dir argument is required
                            with this option.
  -rpc-addr=127.0.0.1:8400  RPC address of the Consul agent.
`
	return strings.TrimSpace(helpText)
}

func (c *KeysCommand) Synopsis() string {
	return "Manages gossip layer encryption keys"
}