11. Exercise: Service Level Agreement

QUESTION:

When drafting a Service Level Agreement (SLA) for your platform, there are many things to consider. You will need to ponder what you will need to implement in order to meet the SLA, and also understand what types of guarantees that you are providing to your customers that you will meet the SLA. Monetary compensation is common for SLA violations either in the form of service credits or outright refunds.

Often when considering what type of SLA a platform can provide, there is a tendency to forget to consider some of the components of the system. If the SLA isn't carefully considered, it can quickly become very difficult and expensive to meet.

Your company would like to offer a 99.9% SLA on your entire platform. Consider the following services that are required for your service to operate normally:

• Email service provider: 99.9%
• DNS provider: 99.99%
• Authentication service provider: 99.9%
• AWS services: 99.9%
• Twitter feed: 99%

Write an SLA for your platform that breaks down acceptable amounts of downtime for your application and for third-party services separately. Also, define periods of excused downtime and caveats for reduced functionality of non-critical components.