看到「Three ways to reduce the costs of your HTTP(S) API on AWS」這邊介紹在 AWS 上省頻寬費用的方法，看了只能一直笑 XD
第一個是降低 HTTP response 裡沒有用到的 header，因為每天有五十億個 HTTP request，所以只要省 1byte 就是省下 USD$0.25/day：
Since we would send this five billion times per day, every byte we could shave off would save five gigabytes of outgoing data, for a saving of 25 cents per day per byte removed.
然後調了一些參數後省下 USD$1,500/month：
Sending 109 bytes instead of 333 means saving $56 per day, or a bit over $1,500 per month.
第二個是想辦法在 TLS 這邊下手，一開始其中一個方向是利用 TLS session resumption 降低第二次連線的成本，但他們發現沒有什麼參數可以調整：
One thing that reduces handshake transfer size is TLS session resumption. Basically, when a client connects to the service for the second time, it can ask the server to resume the previous TLS session instead of starting a new one, meaning that it doesn’t have to send the certificate again. By looking at access logs, we found that 11% of requests were using a reused TLS session. However, we have a very diverse set of clients that we don’t have much control over, and we also couldn’t find any settings for the AWS Application Load Balancer for session cache size or similar, so there isn’t really anything we can do to affect this.
所以改成把 idle 時間拉長 (避免重新連線)：
That leaves reducing the number of handshakes required by reducing the number of connections that the clients need to establish. The default setting for AWS load balancers is to close idle connections after 60 seconds, but it seems to be beneficial to raise this to 10 minutes. This reduced data transfer costs by an additional 8%.
再來是 AWS 本身發的 SSL certification 太肥，所以他們換成 DigiCert 發的，大幅降低憑證本身的大小，反而省下 USD$200/day：
So given that the clients establish approximately two billion connections per day, we’d expect to save four terabytes of outgoing data every day. The actual savings were closer to three terabytes, but this still reduced data transfer costs for a typical day by almost $200.
這些方法真的是頗有趣的 XDDD
不過這些方法也是在想辦法壓榨降低與 client 之間的傳輸量啦，比起成本來說反而是提昇網路反應速度...
