From cc0e970dda93ef4d67823730bcc111be9b485b3d Mon Sep 17 00:00:00 2001
From: Quentin Manfroi <quentin.manfroi@fr.clara.net>
Date: Thu, 22 Mar 2018 21:07:44 +0100
Subject: [PATCH] MON-112 add artificial request for false positive mitigation

---
 cloud/aws/alb/inputs.tf       | 5 +++++
 cloud/aws/alb/monitors-alb.tf | 8 ++++----
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/cloud/aws/alb/inputs.tf b/cloud/aws/alb/inputs.tf
index 32a7278..e6d71dd 100644
--- a/cloud/aws/alb/inputs.tf
+++ b/cloud/aws/alb/inputs.tf
@@ -147,3 +147,8 @@ variable "httpcode_target_5xx_threshold_warning" {
   default     = 60
   description = "target 5xx warning threshold in percentage"
 }
+
+variable "artificial_requests_count" {
+  default     = 5
+  description = "Number of false requests used to mitigate false positive in case of low trafic"
+}
diff --git a/cloud/aws/alb/monitors-alb.tf b/cloud/aws/alb/monitors-alb.tf
index 6e7d823..e03c8d2 100644
--- a/cloud/aws/alb/monitors-alb.tf
+++ b/cloud/aws/alb/monitors-alb.tf
@@ -76,7 +76,7 @@ resource "datadog_monitor" "ALB_httpcode_elb_5xx" {
     sum(last_5m): (
       default(
         avg:aws.applicationelb.httpcode_elb_5xx{${data.template_file.filter.rendered}} by {region,loadbalancer}.as_count() /
-        avg:aws.applicationelb.request_count{${data.template_file.filter.rendered}} by {region,loadbalancer}.as_count(),
+        (avg:aws.applicationelb.request_count{${data.template_file.filter.rendered}} by {region,loadbalancer}.as_count() + ${var.artificial_requests_count}),
       0) * 100
     ) > ${var.httpcode_elb_5xx_threshold_critical}
   EOF
@@ -109,7 +109,7 @@ resource "datadog_monitor" "ALB_httpcode_elb_4xx" {
     sum(last_5m): (
       default(
         avg:aws.applicationelb.httpcode_elb_4xx{${data.template_file.filter.rendered}} by {region,loadbalancer}.as_count() /
-        avg:aws.applicationelb.request_count{${data.template_file.filter.rendered}} by {region,loadbalancer}.as_count(),
+        (avg:aws.applicationelb.request_count{${data.template_file.filter.rendered}} by {region,loadbalancer}.as_count() + ${var.artificial_requests_count}),
       0) * 100
     ) > ${var.httpcode_elb_4xx_threshold_critical}
   EOF
@@ -142,7 +142,7 @@ resource "datadog_monitor" "ALB_httpcode_target_5xx" {
     sum(last_5m): (
       default(
         avg:aws.applicationelb.httpcode_target_5xx{${data.template_file.filter.rendered}} by {region,loadbalancer}.as_count() /
-        avg:aws.applicationelb.request_count{${data.template_file.filter.rendered}} by {region,loadbalancer}.as_count(),
+        (avg:aws.applicationelb.request_count{${data.template_file.filter.rendered}} by {region,loadbalancer}.as_count() + ${var.artificial_requests_count}),
       0) * 100
     ) > ${var.httpcode_target_5xx_threshold_critical}
   EOF
@@ -175,7 +175,7 @@ resource "datadog_monitor" "ALB_httpcode_target_4xx" {
     sum(last_5m): (
       default(
         avg:aws.applicationelb.httpcode_target_4xx{${data.template_file.filter.rendered}} by {region,loadbalancer}.as_count() /
-        avg:aws.applicationelb.request_count{${data.template_file.filter.rendered}} by {region,loadbalancer}.as_count(),
+        (avg:aws.applicationelb.request_count{${data.template_file.filter.rendered}} by {region,loadbalancer}.as_count() + ${var.artificial_requests_count}),
       0) * 100
     ) > ${var.httpcode_target_4xx_threshold_critical}
   EOF