The front door
your app shipped
without.

A gate that forwards the request and then returns the right status has failed at its job twice over: your app did the work, and on the LLM lane the provider was already paid. What matters is not the status code a client sees but whether anything behind eggrd was ever asked.

Until 0.4.0 that was an assertion in a comment. It is now a test. A counting stub stands in for your app, and every denial path asserts it saw exactly zero requests, with a control asserting an admitted request reaches it exactly once, so a counter that never incremented could not make the rest pass vacuously.

The five gates are drawn in evaluation order, and the last column of the schedule below is the one that matters.

The same binary sitting in front of your app can sit in front of your model provider. It parses OpenAI-compatible traffic, counts input, output, cached and reasoning tokens separately, then prices them against a book you supply.

Metering is observe-only until you say otherwise: with no price book and no budgets it counts and reports, and changes nothing about the request. Turn on a budget and the line becomes a ceiling, enforced before the call rather than after the invoice.

An unknown model is a decision, not a default. on_unpriced_model either counts it and flags it, or rejects the request outright, so a model you never priced cannot quietly bill at zero.

# edgeguard.toml
[llm]
enabled = true
on_unpriced_model = "block"

[llm.models."gpt-4o"]
input_per_1m  = 2.5
output_per_1m = 10.0

[[llm.budgets]]
name  = "team-platform"
scope = "key"
unit  = "usd"
limit = 250.0
window = "30d"

[alerts]
budget_consumed_threshold = 0.8

# install
cargo install eggrd

# scaffold a starter config beside your app, then check it before it sees traffic
edgeguard init
edgeguard doctor

The crate is eggrd; the binary it installs is still named edgeguard, an earlier working title kept so existing deployments keep working. init writes an annotated edgeguard.toml and a Dockerfile rather than a blank file, and refuses to clobber either. doctor then lints that config and walks the boot path, so a bad setting fails at your terminal instead of in front of traffic.

# or skip the toolchain entirely
docker run -p 8080:8080 \
  -v ./edgeguard.toml:/etc/edgeguard/edgeguard.toml \
  mancube/eggrd:0.4.0

A static musl binary on distroless: no shell and no package manager inside it to attack. linux/amd64 and linux/arm64, each built on its own native runner. 0.4.0 more than halved the binary, from 16.6 MiB to 7.5 MiB, by dropping aws-lc-sys, which nothing used: it rode in on feature unification, and it was the build's only C dependency, the piece most likely to break a musl or cross target.

There are two shapes, and init picks the right one for what it finds. Either eggrd becomes your container's entrypoint and runs your app as a child on APP_PORT, or it runs as its own service pointed at an upstream URL. Neither needs a line of your application code.

Pick the stack you are on. Every command below is from the example files in the repository, not an illustration of them.

Answering “what does this key actually do?” used to mean opening config.rs. It does not any more. Five pages carry the whole surface, and the largest of them is generated from the source so it cannot describe a binary that does not exist.

A field added without a doc comment fails the generator rather than producing a blank row: a reference with silent holes in it looks complete and is not. Writing it found 21 public config fields with no doc comment at all, which are now documented in the source as well as on the page.