Helm template ignore {{expr}}

helm_ignore_double_curly.yaml

# A viable hack is to let Helm render the template as a raw string. 
# Note the opening and closing curly bracket with a backtick:
#
# Origin: https://github.com/helm/helm/issues/2798#issuecomment-470435015
#
# Excerpt from a Prometheus Alertmanager yaml
receivers:
- name: slack-receiver
  slack_configs:
  - text: |-
      {{`{{ range .Alerts }}
        *Alert:* {{ .Annotations.summary }}
      {{ end }}`}}