Home Assistant certificate expiry notification

Alert: upcoming_cert_expiry

upcoming_cert_expiry:
    name: "TLS Zertifikat läuft bald ab"
    entity_id: binary_sensor.<cert-name>_cert_renew_required
    state: "on"
    repeat:
      - 1440
    can_acknowledge: true
    skip_first: false
    title: >
      {% set state = (states('binary_sensor.<cert-name>_cert_renew_required')) %}
      {% if state == 'on' %}
      ⚠️ TLS Zertifikat läuft bald ab
      {% else %}
      ✅ TLS Zertifikat wurde erneuert
      {% endif %}
    message: >
     Das Zertifikat <cert-name> läuft in {{ states('sensor.<cert-name>_cert_valid_days') }} Tagen am {{ as_timestamp(states('sensor.<cert-name>_cert_expiration_date')) | timestamp_custom('%d.%m.%y') }} ab!
    done_message: >
      Das Zertifikat <cert-name> wurde erneuert und ist noch {{ states('sensor.<cert-name>_cert_valid_days') }} Tage bis zum {{ as_timestamp(states('sensor.<cert-name>_cert_expiration_date')) | timestamp_custom('%d.%m.%y') }} gültig.
    notifiers:
     - grp_notify
    data:
      tag: upcoming-cert-expiry

Template: binary_sensor.<cert-name>_cert_renew_required

{% if int(states('sensor.<cert-name>_cert_valid_days')) is number %}

{% set valid_days = states('sensor.<cert-name>_cert_valid_days') %}

{{ iif(int(valid_days) <= 14, true, false) }}

{% endif %}

Template: sensor.<cert-name>_cert_valid_days

{% if states('sensor.<cert-name>_cert_expiration_date') is not in ["unknown", "unavailable", ""] %}

{% set expiration_date = states('sensor.<cert-name>_cert_expiration_date') %}
{{ (as_datetime(expiration_date) | as_local  - today_at()).days }}

{% endif %}

This Home Assistant config notifies you 14 days before an TLS certificates expires. It requires
the Certificate Expiry
integration which monitors the expiration date of an certificate.
The monitored certificate in the integration has an ID like this:
sensor.<cert-name>_cert_expiration_date
Replace <cert-name> in all the configurations with your preferred name.

• The template sensor calculate the amount of days the certificate will be valid
• The template binary sensor will return true if the certificate is valid for 14 days or less
• The alert will send an alert to your notification group once every day when the binary sensor is true