feat: add EXCLUDE_AT_MATCH env variable to datadog

Datadog lambda will not send lines matching EXCLUDE_AT_MATCH, which will
allow easy exclusion of unwanted events (such as container stopped due
to autoscaling)

By default it's set to $x^ which is a regexp lifted from stack overflow
that doesn't match anything, so everything is included

Author: eugenep-scribd

logshipping.tf

@@ -97,8 +97,9 @@ resource "aws_lambda_function" "dd-log" {
 
   environment {
     variables = {
-      DD_API_KEY = var.datadog_api_key
-      DD_TAGS    = "namespace:${var.namespace},env:${var.env}"
+      DD_API_KEY       = var.datadog_api_key
+      DD_TAGS          = "namespace:${var.namespace},env:${var.env}"
+      EXCLUDE_AT_MATCH = var.log_exclude_at_match
     }
   }
 }

vars.tf

@@ -57,3 +57,8 @@ variable "elb_logs_bucket_prefix" {
   type        = string
   default     = "awsdd"
 }
+variable "log_exclude_at_match" {
+  description = "Sets EXCLUDE_AT_MATCH environment variable, which allows excluding unwanted log lines"
+  type        = "string"
+  default     = "$x^" # <- never matches anything
+}