1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
|
package sysdwatchdog
import (
"errors"
"fmt"
"os"
"strconv"
"time"
sysdnotify "github.com/iguanesolutions/go-systemd/v5/notify"
)
// WatchDog is an interface to the systemd watchdog mechanism
type WatchDog struct {
interval time.Duration
checks time.Duration
}
// New returns an initialized and ready to use WatchDog
func New() (wd *WatchDog, err error) {
// Check WatchDog is supported and usable
interval, err := getWatchDogInterval()
if err != nil {
return
}
// Return the initialized controller
wd = &WatchDog{
interval: interval,
checks: interval / 2,
}
return
}
// based on https://github.com/coreos/go-systemd/blob/master/daemon/watchdog.go
func getWatchDogInterval() (interval time.Duration, err error) {
// WATCHDOG_USEC
wusec := os.Getenv("WATCHDOG_USEC")
if wusec == "" {
err = errors.New("watchdog does not seem to be enabled: WATCHDOG_USEC env unset")
return
}
wusecTyped, err := strconv.Atoi(wusec)
if err != nil {
err = fmt.Errorf("can't convert WATCHDOG_USEC as int: %s", err)
return
}
if wusecTyped <= 0 {
err = fmt.Errorf("WATCHDOG_USEC must be a positive number")
return
}
interval = time.Duration(wusecTyped) * time.Microsecond
// WATCHDOG_PID
wpid := os.Getenv("WATCHDOG_PID")
if wpid == "" {
return // No WATCHDOG_PID: can't check if we are the one, let's go with it
}
wpidTyped, err := strconv.Atoi(wpid)
if err != nil {
err = fmt.Errorf("can't convert WATCHDOG_PID as int: %s", err)
return
}
if os.Getpid() != wpidTyped {
err = fmt.Errorf("WATCHDOG_PID is %d and we are %d: we are not the watched PID", wpidTyped, os.Getpid())
}
return
}
// SendHeartbeat sends a keepalive notification to systemd watchdog
func (c *WatchDog) SendHeartbeat() error {
if !sysdnotify.IsEnabled() {
return errors.New("failed to notify watchdog: systemd notify is diabled")
}
return sysdnotify.WatchDog()
}
// GetChecksDuration returns the ideal time for a client to perform (active or passive collect) checks.
// Is is equal at 1/3 of watchdogInterval
func (c *WatchDog) GetChecksDuration() time.Duration {
return c.checks
}
// GetLimitDuration returns the systemd watchdog limit provided by systemd
func (c *WatchDog) GetLimitDuration() time.Duration {
return c.interval
}
// NewTicker initializes and returns a ticker set at watchdogChecks (which is set at 1/3 of watchdogInterval).
// It can be used by clients to trigger checks before using SendHeartbeat().
func (c *WatchDog) NewTicker() *time.Ticker {
return time.NewTicker(c.checks)
}
|
