Alertmanager can't push notification to dashboard prometheus receiver

[s0nea]

The Alertmanager is unable to send POST requests (alerts) to the <host-url>/api/prometheus_receiver endpoint of the dashboard. Therefor no notification will be shown on the dashboard. I took a look at the alertmanager container log output and found the following error:

"Notify for alerts failed" num_alerts=1 err="ceph-dashboard/webhook[0]: notify retry canceled after 8 attempts: Post \"https://master.ses7-mini.test:8443/api/prometheus_receiver\": x509: certificate is not valid for any names, but wanted to match master.ses7-mini.test"

I figured out a workaround by adapting the alertmanager config and adding insecure_skip_verify to the global section:

# {{ cephadm_managed }}
# See https://prometheus.io/docs/alerting/configuration/ for documentation.

global:
  resolve_timeout: 5m
  http_config:
    tls_config:
      insecure_skip_verify: true

route:
  ...

receivers:
  ...