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LibreNMS pushes alerts through an alert transport of type API: every time an alert rule triggers, changes, or recovers, LibreNMS posts one JSON body to Flashduty, built from the body template on this page. Each device and alert rule pair maps to one Flashduty alert: it opens when the rule triggers and closes automatically when the rule recovers.

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In Flashduty On-call

You can get the integration push URL in either of the following ways.

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Use a dedicated integration

  1. In the Flashduty console, select Channel and open a channel
  2. Select Configuration → Integrations → Private integration, then click Add an integration
  3. Select LibreNMS and click Save
  4. Open the new integration card and copy the Push URL

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Use a shared integration

  1. In the Flashduty console, select Integration Center → Alert Events
  2. Select LibreNMS and enter an integration name
  3. Configure the default route and select a channel. You can add more rules under Routes after creation
  4. Click Save and copy the generated Push URL

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Configure LibreNMS

The steps below need LibreNMS 25.7.0 or later: the body template escapes text fields with the json_encode filter, which is available from 25.7.0.
1

Create the alert transport

Go to Alerts → Alert Transports, click Create alert transport, and fill in the form as follows:
LibreNMS drops everything after ? in the API URL and sends only the Options entries as query parameters. Put integration_key in Options. If it is left in the API URL, Flashduty rejects the request.
Body template:
Do not add quotes around the fields that use |json_encode: the filter already outputs a quoted, escaped JSON string, so quotes or line breaks in a rule name or alert message cannot break the JSON.Leave the other fields at their defaults and click Save.
2

Attach the transport to alert rules

From LibreNMS 26.4.0, alert rules pick their notification transports through an Operation. Earlier versions select Transports directly on the rule. Follow the steps for your version:LibreNMS 26.4.0 and later
  1. Go to Alerts → Operations and create an Operation, or edit the Operation the rule already uses
  2. Add the transport created above to a segment. For a new Operation, set Steps from to 1, Steps to to 1, and Start (s) to 0 to send one notification as soon as the rule matches
  3. Go to Alerts → Alert Rules, edit the rule, and select that Operation under Operation
A rule without an Operation still raises alerts in LibreNMS but sends no notification.LibreNMS 25.7.0 to 26.3.xGo to Alerts → Alert Rules, edit the rule, and select the transport created above under Transports. You can also check Default Alert on the transport so that every rule without its own transports uses it.On both versions, make sure Recovery alerts is on for the rule. Otherwise LibreNMS sends no notification when the rule recovers, and the Flashduty alert stays open. Click Save Rule.
3

Verify the lifecycle

In the Alerts → Alert Transports list, click the test button next to the transport (the yellow check mark icon, tooltip Test transport) and confirm that LibreNMS reports a successful test. The test uses fixed LibreNMS test data (alert_id is 000); Flashduty returns success and creates no alert.Then make a rule really trigger (for example, make a monitored device unreachable so that the Devices up/down rule alerts) and confirm that Flashduty receives an active alert. Bring the device back and confirm that the alert closes. LibreNMS checks alert rules after each poll, so alerts and recoveries usually arrive within one polling interval (5 minutes by default).

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Alert Key

Flashduty uses alert_id as the Alert Key. alert_id is the row ID in the LibreNMS alerts table, which holds exactly one row per device and alert rule, and every trigger, change, and recovery notification carries the same value. The LibreNMS PagerDuty transport uses it as its dedup key too. So notifications for the same rule on the same device land on one alert, and a new trigger after recovery opens a new alert. Changes to the severity, rule name, host name, or alert message do not change the Alert Key. alert_id is unique only within one LibreNMS instance: use a separate Flashduty integration for each LibreNMS instance. Flashduty rejects requests without alert_id or state.

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Alert lifecycle

Flashduty handles notifications by the state field: Rules that use an Operation (LibreNMS 26.4.0 and later) send only trigger, acknowledgement, and recovery notifications, never state 3, 4, or 5. Those three are sent only when the rule selects Transports directly (25.7.0 to 26.3.x). When Acknowledgement alerts is on for a rule, LibreNMS sends a notification with state 2 when the alert is acknowledged. Acknowledgements neither open nor close a Flashduty alert, and ignored notifications get a success response.

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Severity

The severity comes from the Severity of the alert rule: Recovery notifications carry the same rule severity, and the recovery event keeps it.

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Alert content

  • Title: <rule name> on <host name>. When the rule name is empty, LibreNMS rule <rule_id> is used instead
  • Description: the alert message msg rendered from the LibreNMS alert template. The default template includes the title, severity, time, and faulty items
  • Labels: check (rule name), resource and host (host name), alert_id, rule_id, device_id, sys_name, os, location, severity (raw rule severity), state (alert, worse, better, changed, or recovered)
Empty fields are not written as labels.

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Troubleshooting

  • The test fails with Transport delivery failed with 401 and integration_key is required: put integration_key in Options, not in the API URL
  • The test fails with Transport delivery failed with 400: if the response shows {{ $name|json_encode }} unrendered, LibreNMS is older than 25.7.0 and does not know the json_encode filter; upgrade it. Otherwise make sure the fields with |json_encode have no extra quotes and that Send as form is unchecked
  • No alert is sent: on 26.4.0 and later, make sure the rule uses an Operation that contains the transport; on earlier versions, make sure the rule’s Transports include it. Check the send result on the device’s Alerts page or in the Event Log
  • The alert does not recover: make sure Recovery alerts is on for the rule
For the template variables, see the LibreNMS docs Templates and API transport.