Fastly outage of June 8, 2021

On June 8, 2021, at 09:47 UTC, 85% of Fastly's network returned errors. Gov.uk, the New York Times, the Guardian, Reddit, Amazon and hundreds of other sites went offline at the same time. Fastly detected the outage within a minute and restored 95% of the network within 49 minutes. The cause, published the same day, was almost trivial. A customer changed its configuration, in a perfectly valid way; the change triggered a bug introduced in the network software on May 12. One action, one customer, one hour of outage for part of the web. The insured loss was small, because the duration was short and most policies carry a waiting period in hours, often eight to twelve, before paying business interruption. The case matters for what it shows about accumulation. A content delivery network is a common chokepoint the insured does not see, since it often has no direct contract with it. A cyber modeler looking for provider outage scenarios starts from that hour, and multiplies it.