Added a check command

command/check.go

@@ -0,0 +1,93 @@
+package command
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+const (
+	HealthCritical = 1
+	HealthWarn     = 2
+	HealthPass     = 0
+)
+
+type AgentCheckCommand struct {
+	Meta
+}
+
+func (c *AgentCheckCommand) Help() string {
+	helpText := `
+Usage: nomad check
+  
+  Display state of the Nomad agent. The exit code of the command is Nagios
+  compatible and could be used with alerting systems.
+
+General Options:
+
+  ` + generalOptionsUsage() + `
+
+Agent Check Options:
+  
+  -min-peers
+     Minimum number of peers that a server is expected to know.
+`
+
+	return strings.TrimSpace(helpText)
+}
+
+func (c *AgentCheckCommand) Synopsis() string {
+	return "Displays health of the local Nomad agent"
+}
+
+func (c *AgentCheckCommand) Run(args []string) int {
+	var minPeers int
+
+	flags := c.Meta.FlagSet("check", FlagSetClient)
+	flags.Usage = func() { c.Ui.Output(c.Help()) }
+	flags.IntVar(&minPeers, "min-peers", 0, "")
+
+	if err := flags.Parse(args); err != nil {
+		return 1
+	}
+
+	client, err := c.Meta.Client()
+	if err != nil {
+		c.Ui.Error(fmt.Sprintf("error initializing client: %s", err))
+		return HealthCritical
+	}
+
+	info, err := client.Agent().Self()
+	if err != nil {
+		c.Ui.Output(fmt.Sprintf("unable to query agent info: %v", err))
+		return HealthCritical
+	}
+	if _, ok := info["stats"]["nomad"]; ok {
+		return c.checkServerHealth(info["stats"], minPeers)
+	}
+
+	if _, ok := info["client"]; ok {
+		return c.checkClientHealth(info)
+	}
+	return HealthWarn
+}
+
+// checkServerHealth returns the health of a server
+func (c *AgentCheckCommand) checkServerHealth(info map[string]interface{}, minPeers int) int {
+	raft := info["raft"].(map[string]interface{})
+	knownPeers, err := strconv.Atoi(raft["num_peers"].(string))
+	if err != nil {
+		c.Ui.Output(fmt.Sprintf("unable to get known peers: %v", err))
+		return HealthCritical
+	}
+
+	if knownPeers < minPeers {
+		c.Ui.Output(fmt.Sprintf("known peers: %v, is less than expected number of peers: %v", knownPeers, minPeers))
+		return HealthCritical
+	}
+	return HealthPass
+}
+
+func (c *AgentCheckCommand) checkClientHealth(info map[string]map[string]interface{}) int {
+	return HealthPass
+}

commands.go

@@ -30,7 +30,6 @@ func Commands(metaPtr *command.Meta) map[string]cli.CommandFactory {
 				Meta: meta,
 			}, nil
 		},
-
 		"agent": func() (cli.Command, error) {
 			return &agent.Command{
 				Revision:          GitCommit,
@@ -40,13 +39,16 @@ func Commands(metaPtr *command.Meta) map[string]cli.CommandFactory {
 				ShutdownCh:        make(chan struct{}),
 			}, nil
 		},
-
 		"agent-info": func() (cli.Command, error) {
 			return &command.AgentInfoCommand{
 				Meta: meta,
 			}, nil
 		},
-
+		"check": func() (cli.Command, error) {
+			return &command.AgentCheckCommand{
+				Meta: meta,
+			}, nil
+		},
 		"client-config": func() (cli.Command, error) {
 			return &command.ClientConfigCommand{
 				Meta: meta,