This is an example alert manager config that should work to set the proper severity field (hardcoded to warning in this case):
alertmanager:
enabled: true
config:
global:
pager_service: "service_key"
route:
group_by: ['...']
group_wait: 30s
group_interval: 5m
repeat_interval: 12h
receiver: 'pagerduty_service_new'
routes:
- receiver: 'pagerduty_service_new'
match_re:
receiver: 'staging'
receivers:
- name: 'null'
- name: 'pagerduty_service_new'
webhook_configs:
- url: 'https://api.pagerduty.com/'
pagerduty_configs:
- routing_key: {{ global.pager_service }}
class: "{{ range .Alerts }}{{ .Labels.alertname }}{{ end }}"
group: "{{ range .Alerts }}{{ .Labels.namespace }}{{ end }}"
component: "{{ range .Alerts }}{{ .Labels.pod }}{{ end }}"
severity: 'warning'
details:
container: "{{ range .Alerts }}{{ .Labels.container }}{{ end }}"
region: "{{ range .Alerts }}{{ .Labels.region }}{{ end }}"
severity: "{{ range .Alerts }}{{ .Labels.severity }}{{ end }}"
ownership: "{{ range .Alerts }}{{ .Annotations.ownership }}{{ end }}"
summary: "{{ range .Alerts }}{{ .Annotations.summary }}{{ end }}"
runbook_url: "{{ range .Alerts }}{{ .Annotations.runbook_url }}{{ end }}"
description: "{{ range .Alerts }}{{ .Annotations.description }}{{ end }}"