How to create custom email template in Alertmanager?

Configure your email receiver to, for example, display the email’s subject in the headers section and its template-based body of text.

receivers: – name: EmailReceiver – to: [email protected] headers: subject: ‘Summary: {{ .CommonLabels.alertname }} {{ if eq .Status “firing” }}(Firing){{ else }}(Resolved){{ end }}’ html: ‘{{ template “emailcontent.txt” . }}’

As indicated below, add the section templates to your alertmanager.yaml configuration file.

templates: – /etc/alertmanager/config/custom_mail.tmpl

Mount the custom mail.tmpl file in the alertmanager pod at /etc/alertmanager/config. Please take note that the define clause should exactly match the email recipient’s html section:

{{ define “”emailcontent.txt” }} … <content of the email> … {{ end}}

Mount this file in the alertmanager pod, at /etc/alertmanager/config. Get the base64 encoded content of the file.

cat custom_mail.tmpl | base64 -w 0

Insert this in the alertmanager-main secret.

oc edit -n openshift-monitoring edit secret alertmanager-main

Add the below section.

apiVersion: v1 data: alertmanager.yaml: Imdsb2JhbCI6CiAgInJlc29sdmVfdGltZW91dCI6ICI1bSIK…. custom_mail.tmpl: <content from former step>

check the file has been mounted in alertmanager pod.

oc -n openshift-monitoring exec alertmanager-main-0 — ls -l /etc/alertmanager/config total 0 lrwxrwxrwx. 1 root nobody 24 Oct 18 14:59 alertmanager.yaml -> ..data/alertmanager.yaml lrwxrwxrwx. 1 root nobody 15 Oct 18 14:59 custom_mail.tmpl -> ../data/custom_mail.tmpl