Cutting CloudWatch Logs ingest costs with an OSS Rust gateway

If you've ever stared at a CloudWatch Logs bill for an app that writes a lot of events nobody reads, you've probably noticed that for write-heavy, rarely-read workloads ingest dominates storage. AWS bills CloudWatch Logs ingest at $0.50/GB of raw bytes plus a 26 B/event metered overhead (us-east-1 list pricing, 2026-06), and in those workloads the expensive path is writing logs that almost no one queries afterwards.

: the persisted on-disk format is frozen for the 1.x line. Data objects are plain standard zstd over JSONL — no S4-only container. The archive remains readable without the S4 Logs binary:

aws s3 cp s3://bucket/path/file.jsonl.zst - | zstd -dc | jq .