Adding basic CheckMonitor to invoke scripts

This commit is contained in:
Armon Dadgar 2014-01-20 16:44:23 -10:00
parent fc2e2927b7
commit 147018037e
1 changed files with 121 additions and 0 deletions

121
command/agent/check.go Normal file
View File

@ -0,0 +1,121 @@
package agent
import (
"bytes"
"github.com/hashicorp/consul/consul/structs"
"log"
"os/exec"
"runtime"
"sync"
"syscall"
"time"
)
// CheckNotifier interface is used by the CheckMonitor
// to notify when a check has a status update. The update
// should take care to be idempotent.
type CheckNotifier interface {
UpdateCheck(checkID, status string)
}
// CheckMonitor is used to periodically invoke a script to
// determine the health of a given check. It is compatible with
// nagios plugins and expects the output in the same format.
type CheckMonitor struct {
Notify CheckNotifier
CheckID string
Script string
Interval time.Duration
Logger *log.Logger
stop bool
stopCh chan struct{}
stopLock sync.Mutex
}
// Start is used to start a check monitor.
// Monitor runs until stop is called
func (c *CheckMonitor) Start() {
c.stopLock.Lock()
defer c.stopLock.Unlock()
c.stop = false
c.stopCh = make(chan struct{})
go c.run()
}
// Stop is used to stop a check monitor.
func (c *CheckMonitor) Stop() {
c.stopLock.Lock()
defer c.stopLock.Unlock()
if !c.stop {
c.stop = true
close(c.stopCh)
}
}
// run is invoked by a goroutine to run until Stop() is called
func (c *CheckMonitor) run() {
select {
case <-time.After(c.Interval):
c.check()
case <-c.stopCh:
return
}
}
// check is invoked periodically to perform the script check
func (c *CheckMonitor) check() {
// Determine the shell invocation based on OS
var shell, flag string
if runtime.GOOS == "windows" {
shell = "cmd"
flag = "/C"
} else {
shell = "/bin/sh"
flag = "-c"
}
// Create the command
cmd := exec.Command(shell, flag, c.Script)
// Collect the output
var output bytes.Buffer
cmd.Stdout = &output
cmd.Stderr = &output
// Start the check
if err := cmd.Start(); err != nil {
c.Logger.Printf("[ERR] agent: failed to invoke '%s': %s", c.Script, err)
c.Notify.UpdateCheck(c.CheckID, structs.HealthUnknown)
return
}
// Wait for the check to complete
err := cmd.Wait()
c.Logger.Printf("[DEBUG] agent: check '%s' script '%s' output: %s",
c.CheckID, c.Script, output.Bytes())
// Check if the check passed
if err == nil {
c.Logger.Printf("[DEBUG] Check '%v' is passing", c.CheckID)
c.Notify.UpdateCheck(c.CheckID, structs.HealthPassing)
return
}
// If the exit code is 1, set check as warning
exitErr, ok := err.(*exec.ExitError)
if ok {
if status, ok := exitErr.Sys().(syscall.WaitStatus); ok {
code := status.ExitStatus()
if code == 1 {
c.Logger.Printf("[WARN] Check '%v' is now warning", c.CheckID)
c.Notify.UpdateCheck(c.CheckID, structs.HealthWarning)
return
}
}
}
// Set the health as critical
c.Logger.Printf("[WARN] Check '%v' is now critical", c.CheckID)
c.Notify.UpdateCheck(c.CheckID, structs.HealthCritical)
}