Add config command and config validate subcommand to nomad CLI

command/commands.go

@@ -204,6 +204,16 @@ func Commands(metaPtr *Meta, agentUi cli.Ui) map[string]cli.CommandFactory {
 				Meta: meta,
 			}, nil
 		},
+		"config": func() (cli.Command, error) {
+			return &ConfigCommand{
+				Meta: meta,
+			}, nil
+		},
+		"config validate": func() (cli.Command, error) {
+			return &ConfigValidateCommand{
+				Meta: meta,
+			}, nil
+		},
 		// operator debug was released in 0.12 as debug. This top-level alias preserves compatibility
 		"debug": func() (cli.Command, error) {
 			return &OperatorDebugCommand{

command/config.go

@@ -0,0 +1,38 @@
+package command
+
+import (
+	"strings"
+
+	"github.com/mitchellh/cli"
+)
+
+type ConfigCommand struct {
+	Meta
+}
+
+func (f *ConfigCommand) Help() string {
+	helpText := `
+Usage: nomad config <subcommand> [options] [args]
+
+  This command groups subcommands for interacting with configurations.
+  Users can validate configurations for the Nomad agent.
+
+  Validate configuration:
+
+      $ nomad config validate <config_path> [<config_path>...]
+
+  Please see the individual subcommand help for detailed usage information.
+`
+
+	return strings.TrimSpace(helpText)
+}
+
+func (f *ConfigCommand) Synopsis() string {
+	return "Interact with configurations"
+}
+
+func (f *ConfigCommand) Name() string { return "config" }
+
+func (f *ConfigCommand) Run(args []string) int {
+	return cli.RunResultHelp
+}

command/config_validate.go

@@ -0,0 +1,73 @@
+package command
+
+import (
+	"fmt"
+	"strings"
+
+	agent "github.com/hashicorp/nomad/command/agent"
+)
+
+type ConfigValidateCommand struct {
+	Meta
+}
+
+func (c *ConfigValidateCommand) Help() string {
+	helpText := `
+Usage: nomad config validate <config_path> [<config_path...>]
+
+  Performs a thorough sanity test on Nomad configuration files. For each file
+  or directory given, the validate command will attempt to parse the contents
+  just as the "nomad agent" command would, and catch any errors.
+
+  This is useful to do a test of the configuration only, without actually
+  starting the agent. This performs all of the validation the agent would, so
+  this should be given the complete set of configuration files that are going
+  to be loaded by the agent. This command cannot operate on partial
+  configuration fragments since those won't pass the full agent validation.
+
+  Returns 0 if the configuration is valid, or 1 if there are problems.
+`
+
+	return strings.TrimSpace(helpText)
+}
+
+func (c *ConfigValidateCommand) Synopsis() string {
+	return "Validate config files/directories"
+}
+
+func (c *ConfigValidateCommand) Name() string { return "config validate" }
+
+func (c *ConfigValidateCommand) Run(args []string) int {
+	flags := c.Meta.FlagSet(c.Name(), FlagSetClient)
+	flags.Usage = func() { c.Ui.Output(c.Help()) }
+	if err := flags.Parse(args); err != nil {
+		c.Ui.Error(err.Error())
+		return 1
+	}
+
+	configPath := flags.Args()
+	if len(configPath) < 1 {
+		c.Ui.Error("Must specify at least one config file or directory")
+		return 1
+	}
+
+	var config *agent.Config
+
+	for _, path := range configPath {
+		current, err := agent.LoadConfig(path)
+		if err != nil {
+			c.Ui.Error(fmt.Sprintf(
+				"Error loading configuration from %s: %s", path, err))
+			return 1
+		}
+
+		if config == nil {
+			config = current
+		} else {
+			config = config.Merge(current)
+		}
+	}
+
+	c.Ui.Output("Configuration is valid!")
+	return 0
+}

command/config_validate_test.go

@@ -0,0 +1,76 @@
+package command
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/mitchellh/cli"
+)
+
+func TestConfigValidateCommand_SucceedWithEmptyDir(t *testing.T) {
+	t.Parallel()
+	fh, err := ioutil.TempDir("", "nomad")
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	defer os.Remove(fh)
+
+	ui := new(cli.MockUi)
+	cmd := &ConfigValidateCommand{Meta: Meta{Ui: ui}}
+	args := []string{fh}
+
+	code := cmd.Run(args)
+	if code != 0 {
+		t.Fatalf("expected exit 0, actual: %d", code)
+	}
+}
+
+func TestConfigValidateCommand_SucceedWithMinimalConfigFile(t *testing.T) {
+	t.Parallel()
+	fh, err := ioutil.TempDir("", "nomad")
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	defer os.Remove(fh)
+
+	fp := filepath.Join(fh, "config.hcl")
+	err = ioutil.WriteFile(fp, []byte(`datacenter = "abc01"`), 0644)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	ui := new(cli.MockUi)