TLS support.

TLS authentication support between the CLI and Swarm but also between
Swarm and the Docker nodes.

Closes #148.

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>

README.md

@@ -51,6 +51,19 @@ $ swarm list --token=6856663cdefdec325839a4b7e1de38e8
 http://<node_ip:2375>
 ```
 
+### TLS
+
+Swarm supports TLS authentication between the CLI and Swarm but also between Swarm and the Docker nodes.
+
+In order to enable TLS, the same command line options as Docker can be specified:
+
+`swarm manage --tlsverify --tlscacert=<CACERT> --tlscert=<CERT> --tlskey=<KEY> [...]`
+
+Please refer to the [Docker documentation](https://docs.docker.com/articles/https/) for more information on how
+to set up TLS authentication on Docker and generating the certificates.
+
+Note that Swarm certificates must be generated with`extendedKeyUsage = clientAuth,serverAuth`.
+
 ## Participating
 
 We welcome pull requests and patches; come say hi on IRC, #docker-swarm on freenode.

api/api.go

@@ -2,9 +2,11 @@ package api
 
 import (
 	"bytes"
+	"crypto/tls"
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
+	"net"
 	"net/http"
 	"net/url"
 	"regexp"
@@ -362,7 +364,7 @@ func createRouter(c *context, enableCors bool) (*mux.Router, error) {
 	return r, nil
 }
 
-func ListenAndServe(c *cluster.Cluster, s *scheduler.Scheduler, addr, version string, enableCors bool) error {
+func ListenAndServe(c *cluster.Cluster, s *scheduler.Scheduler, addr, version string, enableCors bool, tlsConfig *tls.Config) error {
 	context := &context{
 		cluster:       c,
 		scheduler:     s,
@@ -374,9 +376,19 @@ func ListenAndServe(c *cluster.Cluster, s *scheduler.Scheduler, addr, version st
 	if err != nil {
 		return err
 	}
+
 	server := &http.Server{
 		Addr:    addr,
 		Handler: r,
 	}
-	return server.ListenAndServe()
+
+	l, err := net.Listen("tcp", addr)
+	if err != nil {
+		return err
+	}
+	if tlsConfig != nil {
+		tlsConfig.NextProtos = []string{"http/1.1"}
+		l = tls.NewListener(l, tlsConfig)
+	}
+	return server.Serve(l)
 }

main.go

@@ -54,6 +54,26 @@ func main() {
 		Name:  "api-enable-cors, cors",
 		Usage: "enable CORS headers in the remote API",
 	}
+	flTls := cli.BoolFlag{
+		Name:  "tls",
+		Usage: "Use TLS; implied by --tlsverify=true",
+	}
+	flTlsCaCert := cli.StringFlag{
+		Name:  "tlscacert",
+		Usage: "Trust only remotes providing a certificate signed by the CA given here",
+	}
+	flTlsCert := cli.StringFlag{
+		Name:  "tlscert",
+		Usage: "Path to TLS certificate file",
+	}
+	flTlsKey := cli.StringFlag{
+		Name:  "tlskey",
+		Usage: "Path to TLS key file",
+	}
+	flTlsVerify := cli.BoolFlag{
+		Name:  "tlsverify",
+		Usage: "Use TLS and verify the remote",
+	}
 
 	app.Commands = []cli.Command{
 		{
@@ -91,7 +111,10 @@ func main() {
 			Name:      "manage",
 			ShortName: "m",
 			Usage:     "manage a docker cluster",
-			Flags:     []cli.Flag{flToken, flAddr, flHeartBeat, flEnableCors},
+			Flags: []cli.Flag{
+				flToken, flAddr, flHeartBeat,
+				flTls, flTlsCaCert, flTlsCert, flTlsKey, flTlsVerify,
+				flEnableCors},
 			Action: manage,
 		},
 		{

manage.go

@@ -1,6 +1,10 @@
 package main
 
 import (
+	"crypto/tls"
+	"crypto/x509"
+	"fmt"
+	"io/ioutil"
 	"strings"
 	"time"
 
@@ -22,7 +26,52 @@ func (h *logHandler) Handle(e *cluster.Event) error {
 	return nil
 }
 
+// Load the TLS certificates/keys and, if verify is true, the CA.
+func loadTlsConfig(ca, cert, key string, verify bool) (*tls.Config, error) {
+	c, err := tls.LoadX509KeyPair(cert, key)
+	if err != nil {
+		return nil, fmt.Errorf("Couldn't load X509 key pair (%s, %s): %s. Key encrypted?",
+			cert, key, err)
+	}
+
+	config := &tls.Config{
+		Certificates: []tls.Certificate{c},
+		MinVersion:   tls.VersionTLS10,
+	}
+
+	if verify {
+		certPool := x509.NewCertPool()
+		file, err := ioutil.ReadFile(ca)
+		if err != nil {
+			return nil, fmt.Errorf("Couldn't read CA certificate: %s", err)
+		}
+		certPool.AppendCertsFromPEM(file)
+		config.RootCAs = certPool
+	} else {
+		// If --tlsverify is not supplied, disable CA validation.
+		config.InsecureSkipVerify = true
+	}
+
+	return config, nil
+}
+
 func manage(c *cli.Context) {
+	var (
+		tlsConfig *tls.Config = nil
+		err       error
+	)
+
+	// If either --tls or --tlsverify are specified, load the certificates.
+	if c.Bool("tls") || c.Bool("tlsverify") {
+		tlsConfig, err = loadTlsConfig(
+			c.String("tlscacert"),
+			c.String("tlscert"),
+			c.String("tlskey"),
+			c.Bool("tlsverify"))
+		if err != nil {
+			log.Fatal(err)
+		}
+	}
 
 	refresh := func(c *cluster.Cluster, nodes []string) {
 		for _, addr := range nodes {
@@ -32,7 +81,7 @@ func manage(c *cli.Context) {
 				}
 				if c.Node(addr) == nil {
 					n := cluster.NewNode(addr)
-					if err := n.Connect(nil); err != nil {
+					if err := n.Connect(tlsConfig); err != nil {
 						log.Error(err)
 						return
 					}
@@ -82,5 +131,5 @@ func manage(c *cli.Context) {
 		},
 	)
 
-	log.Fatal(api.ListenAndServe(cluster, s, c.String("addr"), c.App.Version, c.Bool("cors")))
+	log.Fatal(api.ListenAndServe(cluster, s, c.String("addr"), c.App.Version, c.Bool("cors"), tlsConfig))
 }