Test “it”? The change in question wasn’t by fastly but a customer of theirs making a config change. It’s possible that this customer did validate their change somehow.
Fastly obviously didn’t test their code (with the bug) enough, but testing of course can never prove the absence of bugs. Testing for a global deployment like a massive CDN happens to a large extent in prod because you don’t have another globe. You can test on a smaller scale but eventually you run into a problem that only shows itself at full scale.
> We experienced a global outage due to an undiscovered software bug that surfaced on June 8 when it was triggered by a valid customer configuration change.
Their change was bad, that was May 12. Since that seemed OK on May 13,14,… there wasn’t much indicating that change would blow up weeks later. For example if they roll it out gradually, they would reach 100% rollout with all lights being green
The customer change was a valid configuration. That was yesterday.
Fastly obviously didn’t test their code (with the bug) enough, but testing of course can never prove the absence of bugs. Testing for a global deployment like a massive CDN happens to a large extent in prod because you don’t have another globe. You can test on a smaller scale but eventually you run into a problem that only shows itself at full scale.