Cloud Status Alerter

This repository contains a Ruby script that consumes the various service/vender status feeds and posts corresponding alerts to a specified Slack channel as events occur. A Google Cloud Firestore database is used to track a little state to ensure duplicate updates aren't posted.

Organisation

This repository contains the following sub-directories:

• app - Ruby command-line application that runs as a Kubernetes CronJob

• parent-image - Docker parent image containing Ruby and the dependencies required by the application. Used to speed up the Docker build

Building the Applications

Dockerfiles are included for building both the parent image and application.

Environment Variables

The environment variables below are required:

Variable	Purpose
DISABLED_PROVIDERS	Comma-separated list of provider names that should not be loaded.
ENVIRONMENT	Name of the environment i.e. development or production.
FIRESTORE_PROJECT	Name of the Google Cloud project containing the Firestore project
MONITORING_PROJECT	Name of the Google Cloud project containing the Pub/Sub topic to post alerts to
SLACK_PUBSUB_TOPIC	Name of the Pub/Sub topic to post alerts to
STATUS_ALERTS_SLACK_CHANNEL	Name of the Slack channel to post alerts to

Providers

Updates from a status feed source are implemented by providers, which are simply classes within the providers directory that conform to these rules:

• Provider classes must inherit from the Provider base class
• Provider class names must have an initial capital and then be all lower-case e.g. Github
• The provider class's initialize method must set the @icon and @name for use within the Slack message (the icon should be the name of a Slack emoji minus the surrounding colons)
• The provider class must implement a latest_update method that returns a populated StatusFeedUpdate struct. This struct contains the following fields:

Field	Purpose
id	Unique ID for the update. Not displayed, used as a document key in Firestore
timestamp	Timestamp of the update
metadata	Optional additional information about the update e.g. the name of the service affected
text	Status update text
uri	URI for viewing this individual status update online

Providers can be disabled i.e. not loaded by adding their name to the DISABLED_PROVIDERS list.

Copyright

Copyright (C) 2019–2022 Crown Copyright (Office for National Statistics)