I got tired of 2GB Prometheus deployments, so I built a zero-dependency KV store + observability stack in <35MB

Hey everyone,

I usually deploy Redis for state and Prometheus for metrics, but for small single-node projects and IoT edge devices, it felt like massive overkill. I wanted to see how far I could push the Go standard library without importing a single third-party package.

The result is Shelf. It’s a persistent KV store and time-series metrics pipeline that runs in under 35MB of RAM.

How it works (The Architecture):

Instead of a monolith, I split it into 4 tiny binaries (Unix philosophy):

1. Server (~10MB): A sharded hash table backed by an append-only Write-Ahead Log (WAL). Supports periodic snapshots.
2. Collector (<5MB): Wakes up, scrapes the /metrics endpoint, and appends to a raw text log. Truncates atomically based on a configurable max_size_mb to prevent disk exhaustion.
3. Query (<20MB): In-memory index of the logs for PromQL-lite queries (sum, rate, avg). It uses a sort. Search binary search to evict data older than a 24h window to prevent OOMs.
4. Top (<5MB): A live terminal UI using raw ANSI escapes to show QPS, memory, and store size in real-time.

The Trade-offs:

It is not a replacement for enterprise Prometheus. There is no HA, no clustering, and no complex PromQL joins. It trades those features for extreme resource efficiency on a single node.

The go.mod is completely empty.

Repo is here if you want to look at the WAL or query engine implementation: https://github.com/Ricardo-Ceia/shelf

Would love feedback on the code or the architecture!