Alerting

A check that finds a problem is only useful if the right people hear about it, and only trusted if it stays quiet when it should. Contact groups say who to tell, and maintenance windows say when not to.

Contact groups

A contact group is a set of ways to reach people. Checks refer to groups by identifier, so create the group first.

Terminal

$ cakectl contact-group create --name "On call" \
    --email-addresses [email protected],[email protected] \
    --mobile-numbers +441234567890

Flag	Meaning
--name	The name of the group.
--email-addresses	Email addresses to notify.
--mobile-numbers	Mobile numbers to notify, in international format.
--integrations	IDs of integrations to notify.
--ping-url	A URL to request when an alert is raised.

As a file:

contact-group.yaml

name: On call
email_addresses:
- [email protected]
- [email protected]
mobile_numbers:
- "+441234567890"

Then attach the group to checks with --contact-groups:

Terminal

$ cakectl contact-group list
$ cakectl uptime update 123 --contact-groups 456

info

A list of contact groups leaves out email addresses, phone numbers and ping URLs. cakectl contact-group describe ID shows them.

Maintenance windows

A maintenance window silences alerts for the checks it covers while planned work is done, so that a deployment does not wake anyone. It covers checks you name with --tests, checks that carry any of its --tags, or both.

Terminal

$ cakectl maintenance-window create --name "Deploy" \
    --start-at 2026-11-01T22:00:00Z --end-at 2026-11-02T01:00:00Z \
    --timezone Europe/London --tests 123,456

Flag	Meaning
--start-at, --end-at	When the window begins and ends, as RFC 3339 times such as 2026-11-01T22:00:00Z.
--timezone	The IANA time zone of the window, such as Europe/London.
--repeat-interval	How often it recurs: never, 1d, 1w, 2w or 1m.
--tests	IDs of the checks to silence.
--tags	Silence the checks carrying these tags.

Selecting by tag means a window keeps working as checks come and go. A window that silences everything tagged production needs no change when a new production check is added.

weekly-patching.yaml

name: Weekly patching
start_at: 2026-11-07T22:00:00Z
end_at: 2026-11-08T00:00:00Z
timezone: Europe/London
repeat_interval: 1w
tags:
- production

See what is silenced right now with the state filter:

Terminal

$ cakectl maintenance-window list
$ cakectl maintenance-window list --state active

The states are active, pending and paused. maintenance-windows and mw also work in place of maintenance-window.

Next Steps

Look at what your checks have recorded with Reading Results.