Add custom DNS settings to service update

This fix adds `--dns-add`, `--dns-rm`, `--dns-opt-add`, `--dns-opt-rm`,
`--dns-search-add` and `--dns-search-rm` to `service update`.

An integration test and a unit test have been added to cover the changes in this fix.

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

command/service/opts.go

@@ -475,8 +475,14 @@ const (
 	flagContainerLabelRemove  = "container-label-rm"
 	flagContainerLabelAdd     = "container-label-add"
 	flagDNS                   = "dns"
-	flagDNSOptions            = "dns-opt"
+	flagDNSRemove             = "dns-rm"
+	flagDNSAdd                = "dns-add"
+	flagDNSOptions            = "dns-options"
+	flagDNSOptionsRemove      = "dns-options-rm"
+	flagDNSOptionsAdd         = "dns-options-add"
 	flagDNSSearch             = "dns-search"
+	flagDNSSearchRemove       = "dns-search-rm"
+	flagDNSSearchAdd          = "dns-search-add"
 	flagEndpointMode          = "endpoint-mode"
 	flagHostname              = "hostname"
 	flagEnv                   = "env"

command/service/update.go

@@ -48,6 +48,9 @@ func newUpdateCommand(dockerCli *command.DockerCli) *cobra.Command {
 	flags.Var(newListOptsVar(), flagMountRemove, "Remove a mount by its target path")
 	flags.Var(newListOptsVar(), flagPublishRemove, "Remove a published port by its target port")
 	flags.Var(newListOptsVar(), flagConstraintRemove, "Remove a constraint")
+	flags.Var(newListOptsVar(), flagDNSRemove, "Remove custom DNS servers")
+	flags.Var(newListOptsVar(), flagDNSOptionsRemove, "Remove DNS options")
+	flags.Var(newListOptsVar(), flagDNSSearchRemove, "Remove DNS search domains")
 	flags.Var(&opts.labels, flagLabelAdd, "Add or update a service label")
 	flags.Var(&opts.containerLabels, flagContainerLabelAdd, "Add or update a container label")
 	flags.Var(&opts.env, flagEnvAdd, "Add or update an environment variable")
@@ -55,6 +58,10 @@ func newUpdateCommand(dockerCli *command.DockerCli) *cobra.Command {
 	flags.StringSliceVar(&opts.constraints, flagConstraintAdd, []string{}, "Add or update a placement constraint")
 	flags.Var(&opts.endpoint.ports, flagPublishAdd, "Add or update a published port")
 	flags.StringSliceVar(&opts.groups, flagGroupAdd, []string{}, "Add an additional supplementary user group to the container")
+	flags.Var(&opts.dns, flagDNSAdd, "Add or update custom DNS servers")
+	flags.Var(&opts.dnsOptions, flagDNSOptionsAdd, "Add or update DNS options")
+	flags.Var(&opts.dnsSearch, flagDNSSearchAdd, "Add or update custom DNS search domains")
+
 	return cmd
 }
 
@@ -257,6 +264,15 @@ func updateService(flags *pflag.FlagSet, spec *swarm.ServiceSpec) error {
 		}
 	}
 
+	if anyChanged(flags, flagDNSAdd, flagDNSRemove, flagDNSOptionsAdd, flagDNSOptionsRemove, flagDNSSearchAdd, flagDNSSearchRemove) {
+		if cspec.DNSConfig == nil {
+			cspec.DNSConfig = &swarm.DNSConfig{}
+		}
+		if err := updateDNSConfig(flags, &cspec.DNSConfig); err != nil {
+			return err
+		}
+	}
+
 	if err := updateLogDriver(flags, &spec.TaskTemplate); err != nil {
 		return err
 	}
@@ -484,6 +500,71 @@ func updateGroups(flags *pflag.FlagSet, groups *[]string) error {
 	return nil
 }
 
+func removeDuplicates(entries []string) []string {
+	hit := map[string]bool{}
+	newEntries := []string{}
+	for _, v := range entries {
+		if !hit[v] {
+			newEntries = append(newEntries, v)
+			hit[v] = true
+		}
+	}
+	return newEntries
+}
+
+func updateDNSConfig(flags *pflag.FlagSet, config **swarm.DNSConfig) error {
+	newConfig := &swarm.DNSConfig{}
+
+	nameservers := (*config).Nameservers
+	if flags.Changed(flagDNSAdd) {
+		values := flags.Lookup(flagDNSAdd).Value.(*opts.ListOpts).GetAll()
+		nameservers = append(nameservers, values...)
+	}
+	nameservers = removeDuplicates(nameservers)
+	toRemove := buildToRemoveSet(flags, flagDNSRemove)
+	for _, nameserver := range nameservers {
+		if _, exists := toRemove[nameserver]; !exists {
+			newConfig.Nameservers = append(newConfig.Nameservers, nameserver)
+
+		}
+	}
+	// Sort so that result is predictable.
+	sort.Strings(newConfig.Nameservers)
+
+	search := (*config).Search
+	if flags.Changed(flagDNSSearchAdd) {
+		values := flags.Lookup(flagDNSSearchAdd).Value.(*opts.ListOpts).GetAll()
+		search = append(search, values...)
+	}
+	search = removeDuplicates(search)
+	toRemove = buildToRemoveSet(flags, flagDNSSearchRemove)
+	for _, entry := range search {
+		if _, exists := toRemove[entry]; !exists {
+			newConfig.Search = append(newConfig.Search, entry)
+		}
+	}
+	// Sort so that result is predictable.
+	sort.Strings(newConfig.Search)
+
+	options := (*config).Options
+	if flags.Changed(flagDNSOptionsAdd) {
+		values := flags.Lookup(flagDNSOptionsAdd).Value.(*opts.ListOpts).GetAll()
+		options = append(options, values...)
+	}
+	options = removeDuplicates(options)
+	toRemove = buildToRemoveSet(flags, flagDNSOptionsRemove)
+	for _, option := range options {
+		if _, exists := toRemove[option]; !exists {
+			newConfig.Options = append(newConfig.Options, option)
+		}
+	}
+	// Sort so that result is predictable.
+	sort.Strings(newConfig.Options)
+
+	*config = newConfig
+	return nil
+}
+
 type byPortConfig []swarm.PortConfig
 
 func (r byPortConfig) Len() int      { return len(r) }

command/service/update_test.go

@@ -120,6 +120,52 @@ func TestUpdateGroups(t *testing.T) {
 	assert.Equal(t, groups[2], "wheel")
 }
 
+func TestUpdateDNSConfig(t *testing.T) {
+	flags := newUpdateCommand(nil).Flags()
+
+	// IPv4, with duplicates
+	flags.Set("dns-add", "1.1.1.1")
+	flags.Set("dns-add", "1.1.1.1")
+	flags.Set("dns-add", "2.2.2.2")
+	flags.Set("dns-rm", "3.3.3.3")
+	flags.Set("dns-rm", "2.2.2.2")
+	// IPv6
+	flags.Set("dns-add", "2001:db8:abc8::1")
+	// Invalid dns record
+	assert.Error(t, flags.Set("dns-add", "x.y.z.w"), "x.y.z.w is not an ip address")
+
+	// domains with duplicates
+	flags.Set("dns-search-add", "example.com")
+	flags.Set("dns-search-add", "example.com")
+	flags.Set("dns-search-add", "example.org")
+	flags.Set("dns-search-rm", "example.org")
+	// Invalid dns search domain
+	assert.Error(t, flags.Set("dns-search-add", "example$com"), "example$com is not a valid domain")
+
+	flags.Set("dns-options-add", "ndots:9")
+	flags.Set("dns-options-rm", "timeout:3")
+
+	config := &swarm.DNSConfig{
+		Nameservers: []string{"3.3.3.3", "5.5.5.5"},
+		Search:      []string{"localdomain"},
+		Options:     []string{"timeout:3"},
+	}
+
+	updateDNSConfig(flags, &config)
+
+	assert.Equal(t, len(config.Nameservers), 3)
+	assert.Equal(t, config.Nameservers[0], "1.1.1.1")
+	assert.Equal(t, config.Nameservers[1], "2001:db8:abc8::1")
+	assert.Equal(t, config.Nameservers[2], "5.5.5.5")
+
+	assert.Equal(t, len(config.Search), 2)
+	assert.Equal(t, config.Search[0], "example.com")
+	assert.Equal(t, config.Search[1], "localdomain")
+
+	assert.Equal(t, len(config.Options), 1)
+	assert.Equal(t, config.Options[0], "ndots:9")
+}
+
 func TestUpdateMounts(t *testing.T) {
 	flags := newUpdateCommand(nil).Flags()
 	flags.Set("mount-add", "type=volume,source=vol2,target=/toadd")