command: adding client-servers command

command/client_servers.go

@@ -0,0 +1,96 @@
+package command
+
+import (
+	"fmt"
+	"strings"
+)
+
+type ClientServersCommand struct {
+	Meta
+}
+
+func (c *ClientServersCommand) Help() string {
+	helpText := `
+Usage: nomad client-servers [options] [<address>...]
+
+  Query or modify the list of servers on a client node. Client
+  nodes do not participate in the gossip protocol, and register
+  with server nodes periodically over the network. This command
+  can be used to list or modify the set of servers Nomad speaks
+  to during this process.
+
+Examples
+
+    $ nomad client-servers -update foo:4647 bar:4647 baz:4647
+
+General Options:
+
+  ` + generalOptionsUsage() + `
+
+Client Server Options
+
+  -update
+    Updates the client's server list using the provided
+    arguments. Multiple server addresses may be passed using
+    multiple arguments. IMPORTANT: When updating the servers
+    list, you must specify ALL of the server nodes you wish
+    to configure. The set is updated atomically.
+`
+	return strings.TrimSpace(helpText)
+}
+
+func (c *ClientServersCommand) Synopsis() string {
+	return "Query or modify the list of client servers"
+}
+
+func (c *ClientServersCommand) Run(args []string) int {
+	var update bool
+
+	flags := c.Meta.FlagSet("client-servers", FlagSetClient)
+	flags.Usage = func() { c.Ui.Output(c.Help()) }
+	flags.BoolVar(&update, "update", false, "")
+
+	if err := flags.Parse(args); err != nil {
+		return 1
+	}
+
+	// Check the flags for misuse
+	args = flags.Args()
+	if len(args) > 0 && !update {
+		c.Ui.Error(c.Help())
+		return 1
+	}
+	if len(args) == 0 && update {
+		c.Ui.Error(c.Help())
+		return 1
+	}
+
+	// Get the HTTP client
+	client, err := c.Meta.Client()
+	if err != nil {
+		c.Ui.Error(fmt.Sprintf("Error initializing client: %s", err))
+		return 1
+	}
+
+	if update {
+		// Set the servers list
+		if err := client.Agent().SetServers(args); err != nil {
+			c.Ui.Error(fmt.Sprintf("Error updating server list: %s", err))
+			return 1
+		}
+		return 0
+	}
+
+	// Query the current server list
+	servers, err := client.Agent().Servers()
+	if err != nil {
+		c.Ui.Error(fmt.Sprintf("Error querying server list: %s", err))
+		return 1
+	}
+
+	// Print the results
+	for _, server := range servers {
+		c.Ui.Output(server)
+	}
+	return 0
+}

command/client_servers_test.go

@@ -0,0 +1,73 @@
+package command
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/hashicorp/nomad/testutil"
+	"github.com/mitchellh/cli"
+)
+
+func TestClientServersCommand_Implements(t *testing.T) {
+	var _ cli.Command = &ClientServersCommand{}
+}
+
+func TestClientServersCommand_Run(t *testing.T) {
+	srv, _, url := testServer(t, func(c *testutil.TestServerConfig) {
+		c.Client.Enabled = true
+		c.Server.BootstrapExpect = 0
+	})
+	defer srv.Stop()
+
+	ui := new(cli.MockUi)
+	cmd := &ClientServersCommand{Meta: Meta{Ui: ui}}
+
+	// Set the servers list
+	code := cmd.Run([]string{"-address=" + url, "-update", "foo", "bar"})
+	if code != 0 {
+		t.Fatalf("expected exit 0, got: %d", code)
+	}
+
+	// Query the servers list
+	code = cmd.Run([]string{"-address=" + url})
+	if code != 0 {
+		t.Fatalf("expect exit 0, got: %d", code)
+	}
+	out := ui.OutputWriter.String()
+	if !strings.Contains(out, "foo") {
+		t.Fatalf("missing foo")
+	}
+	if !strings.Contains(out, "bar") {
+		t.Fatalf("missing bar")
+	}
+}
+
+func TestClientServersCommand_Fails(t *testing.T) {
+	ui := new(cli.MockUi)
+	cmd := &ClientServersCommand{Meta: Meta{Ui: ui}}
+
+	// Fails on misuse
+	if code := cmd.Run([]string{"some", "bad", "args"}); code != 1 {
+		t.Fatalf("expected exit code 1, got: %d", code)
+	}
+	if out := ui.ErrorWriter.String(); !strings.Contains(out, cmd.Help()) {
+		t.Fatalf("expected help output, got: %s", out)
+	}
+	ui.ErrorWriter.Reset()
+
+	// Fails if updating with no servers
+	if code := cmd.Run([]string{"-update"}); code != 1 {
+		t.Fatalf("expected exit 1, got: %d", code)
+	}
+	if out := ui.ErrorWriter.String(); !strings.Contains(out, cmd.Help()) {
+		t.Fatalf("expected help output, got: %s", out)
+	}
+
+	// Fails on connection failure
+	if code := cmd.Run([]string{"-address=nope"}); code != 1 {
+		t.Fatalf("expected exit code 1, got: %d", code)
+	}
+	if out := ui.ErrorWriter.String(); !strings.Contains(out, "Error querying server list") {
+		t.Fatalf("expected failed query error, got: %s", out)
+	}
+}

commands.go

@@ -40,6 +40,12 @@ func Commands(metaPtr *command.Meta) map[string]cli.CommandFactory {
 			}, nil
 		},
 
+		"client-servers": func() (cli.Command, error) {
+			return &command.ClientServersCommand{
+				Meta: meta,
+			}, nil
+		},
+
 		"eval-monitor": func() (cli.Command, error) {
 			return &command.EvalMonitorCommand{
 				Meta: meta,