Fix bug: Exclude hosts with non-OK HTTP status from lag calculation

Previously, only hosts returning 404 were excluded from lag calculations.
This caused hosts returning other error codes (500, 503, etc.) to still
be used in lag calculations, even though they were unhealthy.

Changed the condition to exclude any host with non-OK (non-200) HTTP status.

- Updated pkg/throttle/mysql.go to check for != StatusOK instead of == StatusNotFound
- Added test case to verify 500 and 503 status codes are properly excluded

Co-authored-by: alexisjcarr <[email protected]>

Author: Copilot

pkg/throttle/mysql.go

@@ -21,7 +21,7 @@ func aggregateMySQLProbes(
 	// so it's safe to iterate it
 	probeValues := []float64{}
 	for _, probe := range *probes {
-		if clusterInstanceHttpChecksMap[mysql.MySQLHttpCheckHashKey(clusterName, &probe.Key)] == http.StatusNotFound {
+		if clusterInstanceHttpChecksMap[mysql.MySQLHttpCheckHashKey(clusterName, &probe.Key)] != http.StatusOK {
 			continue
 		}
 		instanceMetricResult, ok := instanceResultsMap[mysql.GetClusterInstanceKey(clusterName, &probe.Key)]

pkg/throttle/mysql_status_test.go

@@ -0,0 +1,51 @@
+package throttle
+
+import (
+"net/http"
+"testing"
+
+"github.com/github/freno/pkg/base"
+"github.com/github/freno/pkg/mysql"
+
+test "github.com/outbrain/golib/tests"
+)
+
+func TestHttpStatusExclusion(t *testing.T) {
+clusterName := "c0"
+k1 := mysql.GetClusterInstanceKey(clusterName, &key1)
+k2 := mysql.GetClusterInstanceKey(clusterName, &key2)
+k3 := mysql.GetClusterInstanceKey(clusterName, &key3)
+k4 := mysql.GetClusterInstanceKey(clusterName, &key4)
+
+instanceResults := mysql.InstanceMetricResultMap{
+k1: base.NewSimpleMetricResult(1.2),
+k2: base.NewSimpleMetricResult(1.7),
+k3: base.NewSimpleMetricResult(0.3),
+k4: base.NewSimpleMetricResult(2.5),
+}
+
+var probeList mysql.Probes = map[mysql.InstanceKey](*mysql.Probe){}
+for ck := range instanceResults {
+probeList[ck.Key] = &mysql.Probe{Key: ck.Key}
+}
+
+// Test: 500 status should exclude host with worst lag
+httpStatuses := mysql.ClusterInstanceHttpCheckResultMap{
+mysql.MySQLHttpCheckHashKey(clusterName, &key1): http.StatusOK,
+mysql.MySQLHttpCheckHashKey(clusterName, &key2): http.StatusOK,
+mysql.MySQLHttpCheckHashKey(clusterName, &key3): http.StatusOK,
+mysql.MySQLHttpCheckHashKey(clusterName, &key4): http.StatusInternalServerError,
+}
+
+result := aggregateMySQLProbes(&probeList, clusterName, instanceResults, httpStatuses, 0, false, 0)
+lagValue, err := result.Get()
+test.S(t).ExpectNil(err)
+test.S(t).ExpectEquals(lagValue, 1.7)
+
+// Test: 503 status should also exclude
+httpStatuses[mysql.MySQLHttpCheckHashKey(clusterName, &key2)] = http.StatusServiceUnavailable
+result = aggregateMySQLProbes(&probeList, clusterName, instanceResults, httpStatuses, 0, false, 0)
+lagValue, err = result.Get()
+test.S(t).ExpectNil(err)
+test.S(t).ExpectEquals(lagValue, 1.2)
+}