alertmanager webhook can not log alerts

[haowells]

Hi,

I setup a generic webhook (http://alert-webhook.kube-system.xxx/webhook) to collect and logs all alerts 

my config looks like below

route:

  group_by: ['alertname', 'cluster', 'service']

  group_wait: 1m

  group_interval: 5m

  repeat_interval: 15m

  receiver: webhook

  routes:

  - match:

      severity: Critical

    receiver: pager

    continue: true

receivers:

- name: 'webhook'

  webhook_configs:

  - send_resolved: true

    url: 'http://alert-webhook.kube-system.xxx/webhook'

- name: 'pager'

  pagerduty_configs:

  - routing_key: 'xxx'

    url: 'https://events.pagerduty.com/v2/enqueue'

    send_resolved: true

    http_config:

      proxy_url: 'http://httpproxy.xxx'

but somehow this webhook can't receive alerts.  is any way I can run debug why the webhook can't capture alert?

I open the alert manager debug,  I can see it received alert but seem like not send to webhook.

level=debug ts=2020-06-16T13:48:07.742361924Z caller=dispatch.go:201 component=dispatcher msg="Received alert" alert=ETCD_Assertion_Down[15678fb][active]

level=debug ts=2020-06-16T13:48:08.228388735Z caller=dispatch.go:201 component=dispatcher msg="Received alert" alert=Node_Root_Disk_High[3a2ceec][active]