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Add a randomized start before running CheckMonitors. #546

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merged 4 commits into from
Dec 18, 2014
Merged

Add a randomized start before running CheckMonitors. #546

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60dacec
Add a randomized start before running CheckMonitors.
ryanbreen Dec 18, 2014
2e58f54
Well, that sure is cleaner.
ryanbreen Dec 18, 2014
d82ef7b
Test that staggered checks run within the defined interval.
ryanbreen Dec 18, 2014
f2bd641
Clean up log line and reduce test time.
ryanbreen Dec 18, 2014
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5 changes: 4 additions & 1 deletion command/agent/check.go
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Original file line number Diff line number Diff line change
Expand Up @@ -93,7 +93,10 @@ func (c *CheckMonitor) Stop() {

// run is invoked by a goroutine to run until Stop() is called
func (c *CheckMonitor) run() {
next := time.After(0)
// Get the randomized initial pause time
initialPauseTime := randomStagger(c.Interval)
c.Logger.Printf("[DEBUG] agent: pausing %ds before first invocation of %s", int(initialPauseTime.Seconds()), c.Script)
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If you just print a time.Duration directly here as a string, it will get formatted in a nice, human-friendly way by its String() method. That way we don't have to explicitly cast to an int, and we get a more accurate value in the log.

next := time.After(initialPauseTime)
for {
select {
case <-next:
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28 changes: 28 additions & 0 deletions command/agent/check_test.go
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Expand Up @@ -65,6 +65,34 @@ func TestCheckMonitor_BadCmd(t *testing.T) {
expectStatus(t, "foobarbaz", structs.HealthCritical)
}

func TestCheckMonitor_RandomStagger(t *testing.T) {
mock := &MockNotify{
state: make(map[string]string),
updates: make(map[string]int),
output: make(map[string]string),
}
check := &CheckMonitor{
Notify: mock,
CheckID: "foo",
Script: "exit 0",
Interval: 5 * time.Second,
Logger: log.New(os.Stderr, "", log.LstdFlags),
}
check.Start()
defer check.Stop()

time.Sleep(6 * time.Second)
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Let's lower these timing values significantly. I think we can safely use a low value like 10ms for the Interval, and then use testutil.WaitForResult() to wrap checking the map indexes below. This way we can likely complete the test in ~20ms or so, rather than adding 6s to the overall test time. If you grep through the test code for WaitForResult, you will see how we generally use it.

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Actually, WaitForResult is probably not necessary here, but let's definitely use sub-second values for the interval and sleep time.


// Should have at least 1 update
if mock.updates["foo"] < 1 {
t.Fatalf("should have 1 updates %v", mock.updates)
}

if mock.state["foo"] != structs.HealthPassing {
t.Fatalf("should be %v %v", structs.HealthPassing, mock.state)
}
}

func TestCheckMonitor_LimitOutput(t *testing.T) {
mock := &MockNotify{
state: make(map[string]string),
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