Alerts are configured from the Alerting tab when viewing the device or service check or from a group level.
Selecting a metric, comparison and value
Every alert is triggered against a specific metric e.g. disk usage or load average. The comparison works with the value to determine when an alert should be triggered e.g. greater than 5 or regex match to a string.
Some metrics have extra settings, such as disk usage which requires you to specify the mount point (Linux) or drive letter (Windows).
Alert recipients, delays & repeats
Open the alert actions pane to configure who should receive alerts, delays and repeats.
Setting alert recipients
Alerts can be triggered without recipients but to receive alert notifications you need to select who should receive them and through which method.
You can then search all the users on your account and choose whether they should receive notifications via email or SMS. You can also enable notifications via webhooks and PagerDuty if you have enabled these.
Setting alert delays
Alerts will be triggered as soon as the alert condition is matched, however you may not want to receive notifications unless the alert has been open for a period of time. For example if you have occasional load spikes you might not want to be notified every time, so would set a delay so notifications will only be sent if the load remains high for more than 2 minutes.
Setting alert repeats
You will receive a single notification when an alert is opened and another one when the alert is closed. If you want to receive repeated notifications whilst the alert is open you can set a repeat. This will trigger notifications at the selected frequency until the alert is closed.