The Hidden Bill
Most clouds let data in for free but charge for egress, the data that leaves a region or the provider toward the internet. Because each byte is cheap, large or chatty workloads can run up a surprising bill that is hard to notice until it arrives.
Where Egress Hides
The costliest paths are not always obvious.
- Internet egress to users is charged per gigabyte and grows with traffic.
- Cross region and sometimes cross zone transfer carry their own charges.
- Traffic through a NAT gateway is billed for processing on top of the egress itself.
How To Reduce It
Several patterns cut the bill. A content delivery network caches data near users and lowers origin egress. Keeping chatty services in the same zone avoids cross zone transfer. Using private endpoints instead of routing through NAT to a managed service removes both NAT processing and internet egress. Compression and batching shrink the bytes that must leave.
Key idea
Egress is the data leaving a region or the cloud and it is the part you pay for, so caching with a CDN, keeping traffic in one zone, and using private endpoints instead of NAT are the main ways to cut the bill.