wardline

The control-plane proxy that auto-blocks compromised AI agents, all from one static Go binary.

Give an AI agent a thousand tools and no one watching it, and sooner or later it does something you didn't plan for. Maybe it gets prompt-injected. Maybe someone jailbreaks it. Maybe it just goes wrong on its own. However it happens, it starts calling things it never should, and you never wrote a rule to stop that, because you had no idea it was coming.

Wardline sits between your agents and everything they call: MCP servers, tools, gRPC upstreams. Every call goes through it, and on the way it checks who's asking, whether policy allows it, whether there's budget left, and it writes the decision down. Then it does the part a rulebook can't. It learns how each agent normally behaves, and the moment one stops acting like itself, it shuts it down. Right then, while it's happening. No rule for the specific attack, nobody woken up at 2am.

It's a single Go binary. No database to run, no identity provider to wire up, no sidecar. You download it and start it.

See it for yourself

A normal agent goes about its work, gets compromised partway through, and gets shut down for it. This is a real run, not a mockup:

make demo   # runs exactly this on your machine, in about 30 seconds

And here's the whole thing from the operator's side. You sign in, and there's the agent that got blocked, the anomaly that gave it away, the policy it was working against, and who's even allowed to touch any of it:

How it works

Anything that calls a tool (an AI agent, your CLI or IDE, an app) can only reach its upstreams by going through Wardline first. On the way through, it checks identity, applies policy, counts the call against the budget, runs it past anomaly detection, and records what it decided. Then it forwards the call, or it doesn't.

Full design: Architecture.

Related MCP server: guardrails-mcp-server

What it does

The baseline (proxy, policy, audit) is always on. Everything else is one config flag away.

• Catches a compromised agent on its own. Seven detectors watch each agent and learn its normal rhythm as it runs: sudden spikes, tools it has never called before, a climbing deny rate, a combined z-score, a slow drift that no single moment looks wrong on, patterns across a whole tenant, and floods of brand-new identities. There's no training data and nothing to host. When one trips, the agent is actually blocked for a while, not just written to a log. The real hit rates, and the honest gaps, are in the recall benchmark.

• Write policy three ways, still one binary. Plain YAML, OPA/Rego, or AWS Cedar. You pick one with a config key. Nothing external to run, no network hop.

• Real identity, not a header you have to trust. Short-lived signed tokens with refresh and key rotation, sign-in over OIDC or mTLS/SPIFFE, Kubernetes-style RBAC, SCIM for provisioning, and hard tenant isolation.

• Budgets that actually stop a call. Limits per agent and per tenant. A call has to clear both to go through.

• An audit trail an auditor can use. Every decision as structured JSON, a signed evidence bundle you can hand over, retention you control, and a command that reads your real traffic and writes you a starting allow-list.

• See it and scale it. Correlation across instances, OpenTelemetry traces, Prometheus metrics, a live dashboard, and multi-replica HA backed by Postgres.

Getting Started

# From source (always works)
go build -o wardline ./cmd/wardline

# Or pull the published multi-arch image (built for each tagged release)
docker pull ghcr.io/kabirnarang39/wardline:latest

./wardline validate-policy --file policy.yaml.example
./wardline validate-config --config wardline.yaml.example
./wardline serve --config wardline.yaml.example

Point upstream at a real MCP server. Until you do, a proxied call just returns 502 (for a quick test, python3 -m http.server 9000 is enough). Every request carries an X-Wardline-Identity header, and policy matches on that value plus the MCP tool name:

curl -X POST http://localhost:8080 \
  -H "X-Wardline-Identity: agent-abc123" \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"tools/call","params":{"name":"read_file"}}'

Here, X-Wardline-Identity is just a plain header with nothing behind it, so anyone who can reach the proxy can claim to be anyone. That's fine for a local smoke test with no real upstream. It is not fine for anything someone else can reach. Before you point this at a real upstream, turn on credential_issuance (so a signed token replaces the header anyone could fake) and rbac. See Hardening below.

Prebuilt binaries (linux/darwin/windows · amd64/arm64) and multi-arch images ship on every v* tag via Releases and GHCR.

Documentation

Full docs, per-feature design notes, and honest known-limitations live on the docs site:

• Getting Started: install, quickstart, configuration

• Concepts: architecture, policy backends, identity, audit

• Features: every capability in depth

• Deployment: Docker, Helm, HA, observability

• Framework integrations: LangChain, LlamaIndex, OpenAI Agents SDK, CrewAI, raw MCP

Full capability list

Everything below is shipped and testable under internal/features/. The v0.1 baseline (proxy + policy + audit) is always on; everything else is gated by a config flag.

Performance

These are real go test -bench numbers you can reproduce, not figures off a slide:

• Policy decision: about 33 ns and zero allocations at 10 rules (YAML backend, Apple Silicon), around 2.4 µs at 1000 rules.

• The full seven-detector stack: about 299 ns per call and 5 allocations with everything on (around 255 ns for the original four).

• Race-tested: 205 goroutines at once (5 tenants, 40 identities each, plus 5 attackers) all hitting one shared Detector under go test -race, with no data race.

• False positives: ml_score stays at 0 out of 6,000 windows across 20 seeds on steady traffic.

The full recall curve for each attack shape, plus the adversarial battery (sybil, mimicry ceiling, burst-pause, disposable-identity rotation), are in the recall benchmark.

Security

By default, the dashboard and the X-Wardline-Identity header are unauthenticated. Turn on credential_issuance and/or rbac before they count as security at all. Everything optional is off by default and fails closed, and on startup Wardline prints a WARN for every insecure default you've left in place, so you're never guessing about where you stand. Found a vulnerability? See SECURITY.md.

Hardening

Out of the box the proxy fails closed on policy, but identity and the dashboard are wide open. For anything real, turn these on:

features:
  credential_issuance: true   # verify a signed bearer token instead of trusting X-Wardline-Identity
  rbac: true                  # gate the dashboard and admin actions on real permissions

With credential_issuance on, a signed token replaces the header anyone could fake. With rbac on, both viewing the dashboard and changing anything require an identity that's actually allowed to. One thing worth being honest about: ml_score and auto_block catch loud, sudden abuse well, but not a slow ramp. drift_detection (a CUSUM control chart, on by default in the shipped config) closes most of that gap, and the measured numbers are in the recall benchmark. One real gap stays: an attacker who has read the public thresholds can hold a roughly 1.15x ramp forever, which is written up plainly in known limitations. So keep explicit policy and budget limits as your hard floor no matter what.

Project status

Wardline is young and moving fast. Every feature's docs page is deliberately blunt about what it does and doesn't do. Feedback, issues, and contributions are welcome, especially on the anomaly-detection approach and threat model.

Contributing

See CONTRIBUTING.md and CODE_OF_CONDUCT.md. Architecture and engineering conventions are documented in CLAUDE.md; the roadmap lives in the docs.

License

Apache 2.0.