cortex

A Rust reverse-proxy and fleet management layer for multi-node mistral.rs inference clusters.

Problem

Running local LLMs across multiple GPU nodes (different VRAM tiers, different model affinities) requires a unified API surface that:

• Presents a single /v1/models catalogue merging every model across every node.
• Routes requests to the correct node based on where a model is loaded (or can be loaded).
• Manages model lifecycle — unload cold models, reload on demand, pin critical ones — using the mistral.rs /v1/models/{unload,reload,status} HTTP API (PR #1828+).
• Translates between OpenAI and Anthropic request/response envelopes so every client in the homelab speaks whichever dialect it prefers.
• Captures per-request metrics (tokens, tok/s, TTFT, latency) and exposes them as Prometheus counters/histograms.

Architecture

┌──────────────┐  ┌──────────┐  ┌────────────┐  ┌────────────┐
│ Claude Code  │  │ Zed/IDE  │  │ Tidal / mm │  │ curl / etc │
└──────┬───────┘  └─────┬────┘  └──────┬─────┘  └──────┬─────┘
       │                │              │               │
       └────────────────┴──────┬───────┴───────────────┘
                               │
                    ┌──────────▼──────────┐
                    │   cortex     │
                    │   (cortex-gateway)      │
                    │                     │
                    │  Router · Metrics   │
                    │  Evictor · Translate│
                    └──┬──────┬────────┬──┘
                       │      │        │
            ┌──────────▼┐  ┌──▼─────┐  ┌▼──────────┐
            │ gpu-large │  │gpu-med │  │ gpu-small │
            │ mistralrs │  │mistral │  │ mistralrs │
            │ serve     │  │rs serve│  │ serve     │
            │ :8080     │  │ :8080  │  │  :8080    │
            └───────────┘  └────────┘  └───────────┘
                  private network (.internal)

Crates

Crate	Purpose
cortex-core	Shared types: config, node/model state, metrics, OpenAI/Anthropic request/response envelopes
cortex-gateway	Axum HTTP server: proxy, router, evictor, metrics exporter
cortex-agent	Per-node sidecar: polls local mistralrs, reports to gateway, handles restart/defrag
cortex-cli	CLI entrypoint (cortex serve, cortex status, etc.)

Node setup

Each GPU node runs mistralrs serve with a multi-model config. Models are declared but start unloaded — mistral.rs lazy-loads on first request and the gateway can explicitly unload/reload via the HTTP API.

Example node systemd unit:

# /etc/systemd/system/mistralrs.service
[Unit]
Description=mistral.rs inference server
After=network-online.target
Wants=network-online.target

[Service]
Type=simple
ExecStart=/usr/local/bin/mistralrs serve \
    --from-config /etc/mistralrs/config.toml \
    --port 8080
Restart=on-failure
RestartSec=5
Environment=CUDA_VISIBLE_DEVICES=0,1

[Install]
WantedBy=multi-user.target

Gateway config

# cortex.toml
[gateway]
listen = "0.0.0.0:8000"
metrics_listen = "0.0.0.0:9100"

[eviction]
strategy = "lru"        # lru | priority
defrag_after_cycles = 50

[[nodes]]
name = "gpu-large"
endpoint = "http://gpu-large.internal:8080"
vram_mb = 49_152        # e.g. 2x RTX 4090
pinned = ["your-org/large-model"]

[[nodes]]
name = "gpu-medium"
endpoint = "http://gpu-medium.internal:8080"
vram_mb = 24_576        # e.g. RTX 4090
pinned = ["your-org/medium-model"]

[[nodes]]
name = "gpu-small"
endpoint = "http://gpu-small.internal:8080"
vram_mb = 12_288        # e.g. RTX 3060
pinned = ["your-org/embedding-model"]

Building

cargo build --release

Running

# start the gateway
cortex serve --config cortex.toml

# check fleet status
cortex status

# list all models across nodes
curl http://localhost:8000/v1/models

License

GPL-3.0