Add liveness/readiness probe parameters

- PeriodSeconds - How often to probe
- SuccessThreshold - Number of successful probes to go from failure to success state
- FailureThreshold - Number of failing probes to go from success to failure state

This commit includes to changes in behavior:

1. InitialDelaySeconds now defaults to 10 seconds, rather than the
kubelet sync interval (although that also defaults to 10 seconds).
2. Prober only retries on probe error, not failure. To compensate, the
default FailureThreshold is set to the maxRetries, 3.

pkg/api/testing/fuzzer.go

@@ -283,6 +283,18 @@ func FuzzerFor(t *testing.T, version string, src rand.Source) *fuzz.Fuzzer {
 			c.FuzzNoCustom(ct)                                          // fuzz self without calling this function again
 			ct.TerminationMessagePath = "/" + ct.TerminationMessagePath // Must be non-empty
 		},
+		func(p *api.Probe, c fuzz.Continue) {
+			c.FuzzNoCustom(p)
+			// These fields have default values.
+			intFieldsWithDefaults := [...]string{"TimeoutSeconds", "PeriodSeconds", "SuccessThreshold", "FailureThreshold"}
+			v := reflect.ValueOf(p).Elem()
+			for _, field := range intFieldsWithDefaults {
+				f := v.FieldByName(field)
+				if f.Int() == 0 {
+					f.SetInt(1)
+				}
+			}
+		},
 		func(ev *api.EnvVar, c fuzz.Continue) {
 			ev.Name = c.RandString()
 			if c.RandBool() {