Cannot figure out interpreting JSON variable if using "."

[pradeepjairamani]

Hello,
I am trying to use elastalert2 post2 method
http_post2_payload:
title: "Falco Alert"
description: "Docker Client is Running inside Kubernetes. Please check in Kibana.\n container name: {{output_fields.container.image.repository}}"

log looks like this
"output_fields": {
"k8s.pod.name": "gitlab-gitlab-runner-596bcd7b57-q72l8",
"container.image.repository": "gitlab/gitlab-runner",

I am facing this error, not sure how to interpret the variable if it already contains "."
ERROR:elastalert:Uncaught exception running rule docker_client_inside_kubernetes: 'dict object' has no attribute 'container'

Can anybody help me on this?