alerta-blackout-regex 2.0.0

Alerta Blackout enhancement plugin

Alerta plugin to enhance the blackout management, by matching the alerts against blackouts with PCRE (Perl Compatible Regular Expression) on attributes.

A blackout is considered matched when all its attributes are matched.

Once an alert is identified as matching a blackout, a special label is applied, with the format: regex_blackout=<blackout id>, where blackout id is the ID of the matched blackout, e.g., regex_blackout=d8ba1d3b-dbfd-4677-ab00-e7f8469d7ad3. This way, when the alert is fired again, there’s no need to verify the matching again, but simply verify whether the blackout referenced is still active.

Important

Beginning with version 2.0.0, the behaviour has changed, and instead of evaluating the alert into the post_receive hook, this plugin now evaluates the alerts through the pre_receive hook. The reasoning was that post_receive would set the blackout status after the alert has been sent to other plugins, which has resulted in confusing behaviour.

That said, the plugin has been changed to process the alert in pre_receive and therefore before the alert has been correlated. As the Blackouts are retrieved from the Alerta API as unfortunately there’s no other way to gather the Blackouts from a plugin via other internal mechanisms, processing each and every alert throguh pre_receive would put a lot more workload on your Alerta API. To reduce this, the blackout_regex plugin now caches the Blackouts locally, into a file. To fine tune this behaviour for your own setuo you are able to set a few environment variables. See more details below, under the _Configuration_ section.

Installation

This plugin is designed to be installed on the Alerta server; the package is available on PyPI so you can install as:

pip install alerta-blackout-regex

Configuration

Add blackout_regex to the list of enabled PLUGINS in alertad.conf server configuration file and set plugin-specific variables either in the server configuration file or as environment variables.

PLUGINS = ['blackout_regex']

Note

To ensure this plugin won’t affect the existing Blackouts you may have in place, it is recommended to list the blackout_regex plugin after the native blackout plugin in the PLUGINS configuration option or environment variable.

To model the caching behaviour, from version 2.0.0 onwards, you can set the following environment variables:

• ALERTA_BLACKOUT_CACHE_ENABLED - boolean value, by default True; values that equally provide the True logical value: "True", "true", "1", 1.

• ALERTA_BLACKOUT_CACHE_FILE - the location where to cache the blackouts into a file. By default: /var/cache/alerta/blackout_regex. Alerta needs writing access to that directory (or at least rights to be able to create the directory), otherwise it’ll raise an error; the plugin can go ahead with it, but then it won’t be able to cache the Blackouts which may result in an increased workload on your Alerta API.

• ALERTA_BLACKOUT_CACHE_TIME - the amount of time to cache the Blackouts for, in seconds. The default value is 60 seconds.

References

• Suppressing Alerts using Blackouts

License

Copyright (c) 2020-2021 Mircea Ulinic. Available under the Apache License 2.0.