termination

AWS 改善了 EC2 Spot Instance 的關機通知，在決定 terminate 前兩分鐘 instance 可以得知消息，讓 instance 可以處理「後事」，像是將計算的資料寫回 EBS 或是 S3：「New – EC2 Spot Instance Termination Notices」。

Today we are improving the reclamation process with the addition of a two-minute warning, formally known as a Spot Instance Termination Notice.

不過目前不是 trigger，而是透過 polling 的方式提供：

The Termination Notice is accessible to code running on the instance via the instance’s metadata at http://169.254.169.254/latest/meta-data/spot/termination-time. This field will become available when the instance has been marked for termination (step 3, above), and will contain the time when a shutdown signal will be sent to the instance’s operating system.

建議的 polling 時間是五秒鐘一次：

We recommend that interested applications poll for the termination notice at five-second intervals.

至少有方法得知了...