scripts: example lua script to do rate limiting

Added example congif file and removed env variables

Signed-off-by: Gokul R <gokulradhakrish@gmail.com>

Author: Gokul-Radhakrishnan

conf/rate_limit.conf

@@ -0,0 +1,25 @@
+[SERVICE]
+    Flush        1
+    Daemon       Off
+    Log_Level    info
+    Parsers_File parsers.conf
+
+[INPUT]
+    Name          tail
+    Path          /var/log/containers/*.log
+    Parser        docker
+    Tag           kube.*
+    Mem_Buf_Limit 5MB
+
+[FILTER]
+    Name   kubernetes
+    Match  kube.*
+# This filter calls the rate limit script
+[FILTER]
+    Name   lua
+    Match  kube.*
+    script rate_limit.lua
+    call   rate_limit
+[OUTPUT]
+    Name  stdout
+    Match *

scripts/rate_limit.lua

@@ -4,16 +4,16 @@
    sample configuration:
     [FILTER]
      Name lua
-     Match kubernetes.*
+     Match kube.*
      script rate_limit.lua
      call rate_limit
 ]]
 
 local counter = {}
 local time = 0
-local group_key = os.getenv("GROUP_KEY") -- Used to group logs. Groups are rate limited independently. Example: docker_id
-local group_bucket_period_s = tonumber(os.getenv("GROUP_BUCKET_PERIOD_S")) -- This is the period of of time in seconds over which group_bucket_limit applies. Example: 60
-local group_bucket_limit = tonumber(os.getenv("GROUP_BUCKET_LIMIT")) -- Maximum number logs allowed per groups over the period of group_bucket_period_s. Example: 6000 
+local group_key = "docker_id" -- Used to group logs. Groups are rate limited independently.
+local group_bucket_period_s = 60 -- This is the period of of time in seconds over which group_bucket_limit applies.
+local group_bucket_limit = 6000 -- Maximum number logs allowed per groups over the period of group_bucket_period_s.
 
 -- with above values, each and every containers running on the kubernetes will have a limit of 6000 logs for every 60 seconds since contianers have unique kubernetes.docker_id value