A simple alerting mechanism for Salesforce.com, with a sample Slack integration. There's a blog post here to elaborate on this. It's also a part of the series I am writing about monitoring your Salesforce enterprise.
This class uses a sample alert mechanism for sending a message to a Slack channel when Salesforce Governor Limits are breached or nearing.
The limit levels can be set in the custom metadata Config__mdt. A default value of 70% for WARNING and 90% for SEVERE messages is already configured in the metadata with the name All. If a particular limit needs to be changed, a new metadata record can be introduced with that name. For example, if storage space is already at 85% and you'd like to be alerted only at 95% and 99% for warning and severe messages, respectively, then you'd need to add a new custom metadata record for Config__mdt. The key would be DataStorageMB (same as what the API returns), and values would be correspondingly configured. This is also present as an example record in the customMetadata directory.
There are interfaces for Alert and AlertInvoker so custom alerts can easily be built.
In the current codebase, a sample Slack integration is provided.
First, configure the Slack params in the Config__mdt metadata.
Use this for scheduling the alerts:
BaseScheduler base = new BaseScheduler();
String sch = '0 21 20 * * ?';
String jobID = System.schedule('Alert job', sch, base);
When the governor limits reach the specified values, a Slack alert will be triggered.