prometheus/alertmanager/notification/slack.yml

parameters:
  prometheus:
    alertmanager:
      config:
        route:
          routes:
            slack:
              receiver: HTTP-slack
              match_re:
                - label: route
                  value: slack
        receiver:
          HTTP-slack:
            enabled: true
            slack_configs:
              slack-endpoint:
                api_url: "${_param:alertmanager_notification_slack_api_url}"
                send_resolved: true