Dynamic Email Subject in Alert Manager

[Bibin John]

I have few alerts configured in promertheus/alertmanager. I want to dynamically change email subject based on group name. how is it possible? lets say below is one of the entry.

so in below case, email subject should be alert name or suject label value. is this possible?

- alert: OfflinePartitionAlerts

    expr: kafka_controller_kafkacontroller_offlinepartitionscount{job=~"prod_.*"}>0

    for: 2m

    labels:

      group: OfflinePartition

      environment: Production

      subject: OfflinePartitionAlerts

    annotations:

      Environment: 'Production'

      Cluster: '{{ $labels.job }}'

      Node: '{{ $labels.node }}'

      Summary: 'Offline partitions in cluster'

      OfflinePartitionCount : '{{ $value }} '

Thanks

Bibin John

[Christian Hoffmann]

Hi,

(sorry, just found this mail after I replied to your other mail)

On 3/7/20 8:49 PM, Bibin John wrote:
> I have few alerts configured in promertheus/alertmanager. I want to
> dynamically change email subject based on group name. how is it
> possible? lets say below is one of the entry.
> so in below case, email subject should be alert name or suject label
> value. is this possible?

Yes, this should be possible.

First, you can set the email options such as subject or body
per-receiver, which already gives you some flexibility.
Second, the string is templatable -- meaning you can reference a
variable (e.g. a label), which may already be what you want.
You could even work with conditionals there.

This shows the default template for the mail subject:
https://github.com/prometheus/alertmanager/blob/master/template/default.tmpl#L84
https://github.com/prometheus/alertmanager/blob/master/template/default.tmpl#L4

You can find more details about the available fields here:
https://prometheus.io/docs/alerting/notifications/

This shows the configuration:
https://prometheus.io/docs/alerting/configuration/#email_config

And here are some more examples:
https://prometheus.io/docs/alerting/notification_examples/

Hope this helps,
Christian