For Kong Gateway in Kubernetes medium article

medium-kong-gw-for-k8s-serverless-plugin.yaml

apiVersion: configuration.konghq.com/v1
kind: KongPlugin
metadata:
  name: read-jwt-token
  labels:
    global: "true"
disabled: false
config:
  functions:
  - return function()
      local ngx = require "ngx.base64"
      local json = require "cjson"
      local jwt = kong.request.get_header("authorization")

      local header, data, sig = string.match(jwt, "(.*)%.(.*)%.(.*)")

      local dcd = ngx.decode_base64url(data)
      local jdcd = json.decode(dcd)

      -- now do something with your jwt payload.
      
      for k,v in pairs(jdcd) do
        print(v)
      end

    end
plugin: post-function