# SlimFaas
**Repository Path**: mirrors_sync/SlimFaas
## Basic Information
- **Project Name**: SlimFaas
- **Description**: No description available
- **Primary Language**: Unknown
- **License**: Apache-2.0
- **Default Branch**: main
- **Homepage**: None
- **GVP Project**: No
## Statistics
- **Stars**: 0
- **Forks**: 0
- **Created**: 2026-02-20
- **Last Updated**: 2026-02-20
## Categories & Tags
**Categories**: Uncategorized
**Tags**: None
## README
# SlimFaas: The Slimmest, Simplest & Autoscaling-First Function-as-a-Service
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SlimFaas is a lightweight, plug-and-play Function-as-a-Service (FaaS) platform for Kubernetes (and Docker-Compose / Podman-Compose).
It’s designed to be **fast**, **simple**, and **extremely slim** — with a very opinionated, **autoscaling-first** design:
- `0 → N` wake-up from HTTP history & schedules,
- `0 → N` wake-up from **Kafka lag** via the companion **SlimFaas Kafka** service,
- `N → M` scaling powered by PromQL,
- internal metrics store, debug endpoints, and scale-to-zero out of the box.
- temporary **Data Files** endpoints to ingest and stage binaries (from tiny to very large) with TTL-friendly storage — perfect for caching & agentic workflows.
- temporary **Data Sets** endpoints (`/data/sets`) to store small, Redis-like KV payloads (cache, JSON state, flags) with optional TTL — replicated through the cluster via a robust consensus layer.
> **Looking for MCP integration?**
> Check out **[SlimFaas MCP](https://slimfaas.dev/mcp)** — the companion runtime that converts *any* OpenAPI definition into MCP-ready tools on the fly.
---
## Why Use SlimFaas?
### 🚀 Autoscaling that actually understands your traffic
- **Scale-to-zero & wake-up**
- Scale down to `0` after inactivity with configurable timeouts.
- Wake up from `0 → N` based on real HTTP traffic and/or cron-like schedules.
- Wake up from `0 → N` based on **Kafka topic activity**, using **SlimFaas Kafka** to monitor consumer lag and call the SlimFaas wake-up API.
- Control initial capacity with `ReplicasAtStart` to reduce cold-start impact.
- **Two-phase scaling model**
- **`0 → N`**: driven by HTTP history, schedules, **and Kafka lag (SlimFaas Kafka)** to bring functions online only when they’re needed.
- **`N → M`**: driven by a built-in PromQL mini-evaluator on top of an internal metrics store.
- Metrics-based autoscaling only runs when at least one pod exists — no reliance on non-existent metrics.
- **PromQL-driven autoscaler**
- Express scaling rules with PromQL-style queries, for example:
- `sum(rate(http_server_requests_seconds_count{namespace="...",job="..."}[1m]))`
- `max_over_time(slimfaas_function_queue_ready_items{function="my-func"}[30s])`
- `histogram_quantile(0.95, sum by (le) ( rate(http_server_requests_seconds_bucket{...}[1m]) ))`
- Choose whether thresholds are **per pod** (`AverageValue`) or **global** (`Value`).
- Configure scale-up/scale-down policies and stabilization windows inspired by HPA/KEDA.
- **Integrated metrics scraping**
- SlimFaas scrapes only the Prometheus-style HTTP metrics endpoints of pods with `prometheus.io/scrape: "true"`.
- It stores only the **metric keys that are requested** in autoscaling triggers or debug queries.
- A single designated node scrapes and persists metrics; all other nodes read from the same store.
- **Debug-friendly**
- `POST /debug/promql/eval` – evaluate a PromQL expression against the internal store and see the scalar result.
- `GET /debug/store` – inspect what metrics are being scraped, how many series exist, and retention size.
- Designed so you can easily answer: *“What does SlimFaas see when it decides to scale?”*
- **FinOps-minded**
- 30-minute metrics retention window for predictable memory usage.
- Native scale-to-zero and schedules to keep non-critical workloads cold when they’re not needed.
- Slim control-plane footprint to avoid burning resources in your autoscaling logic itself.
### 🧵 Synchronous and Asynchronous Functions
- Simple HTTP endpoints for both **sync** and **async** calls.
- Async mode:
- Limit the number of concurrent requests per function.
- Configure retry behaviors and backoff strategies.
- Drive autoscaling decisions from queue metrics.
### ⏱ Jobs
- Run **one-off**, **batch**, and **scheduled (cron)** jobs via HTTP calls.
- Configure:
- concurrency,
- visibility (public/private),
- retry behavior.
### 🔐 Private/Public Functions and Jobs
- Mark functions as **public** or **private**:
- Private: only accessible from within the cluster or from trusted pods.
- Public: fronted by Ingress / API Gateways as usual.
### 📣 Publish/Subscribe Internal Events
- Synchronously send events to **every replica** of selected functions.
- No additional event bus required — ideal for cluster-local fan-out, cache invalidation, configuration refresh, etc.
### 🧰 Data Files & Data Sets (real-time ingestion + ephemeral caching + robust KV)
SlimFaas includes two complementary “data” APIs:
#### 📁 Data Files (temporary binary artifacts)
**Data Files** endpoints are designed to **stream, store, and serve temporary files** — from tiny payloads to *very large* binaries.
Ideal for **agentic workflows** and **real-time ingestion**: upload once, get an `id`, then let tools/functions consume it when they’re ready.
- Stream-first uploads (without buffering in memory or disk)
- **Agentic-ready** attachments & multi-step flows
- **Ephemeral caching** for intermediate artifacts
- **TTL-based** lifecycle (auto-expiration)
#### 🧠 Data Sets (Redis-like KV for small state)
**Data Sets** endpoints provide a **small, Redis-like KV store** (raw bytes) replicated across the SlimFaas cluster.
- Stream-first uploads
- Store **anything small**: JSON, strings, flags, lightweight cache entries
- Optional `ttl` in **milliseconds** (auto-expiration)
- Hard limit: **1 MiB per value**
### 🧠 “Mind Changer” (Status & Wake-up API)
- Built-in REST APIs to:
- monitor function and replica status,
- wake functions up on demand,
- integrate autoscaling state into your own tools/dashboards.
### 🔌 Plug and Play
- Deploy SlimFaas as a standard pod/StatefulSet with minimal configuration.
- Onboard existing workloads simply by adding annotations:
- let SlimFaas manage their scaling without rewriting your applications.
### ⚡ Slim & Fast
- Written in .NET with:
- focus on performance and low memory footprint,
- AOT-friendly design,
- minimal dependency surface.
---
## Ready to Get Started?
Check out:
- [Get Started](https://github.com/SlimPlanet/SlimFaas/blob/main/documentation/get-started.md) – Learn how to deploy SlimFaas on Kubernetes or Docker Compose.
- Scaling
- [Autoscaling](https://github.com/SlimPlanet/SlimFaas/blob/main/documentation/autoscaling.md) – Deep-dive into `0 → N` / `N → M` autoscaling, PromQL triggers, metrics scraping, and debug endpoints.
- [Kafka Connector](https://github.com/SlimPlanet/SlimFaas/blob/main/documentation/kafka.md) – Use Kafka topic lag to wake functions from `0 → N` and keep workers alive while messages are still flowing.
- [Planet Saver](https://github.com/SlimPlanet/SlimFaas/blob/main/documentation/planet-saver.md) – See how to start and monitor replicas from a JavaScript frontend.
- Functions & Workloads
- [Functions](https://github.com/SlimPlanet/SlimFaas/blob/main/documentation/functions.md) – See how to call functions synchronously or asynchronously.
- [Events](https://github.com/SlimPlanet/SlimFaas/blob/main/documentation/events.md) – Explore how to use internal synchronous publish/subscribe events.
- [Jobs](https://github.com/SlimPlanet/SlimFaas/blob/main/documentation/jobs.md) – Learn how to define and run one-off jobs.
- [OpenTelemetry](https://github.com/SlimPlanet/SlimFaas/blob/main/documentation/opentelemetry.md) – Enable distributed tracing, metrics, and logs with OpenTelemetry integration.
- Data & Files
- [Data Files](https://github.com/SlimPlanet/SlimFaas/blob/main/documentation/data-files.md) - Understand how to ingest, store, and serve temporary binary artifacts.
- [Data Sets](https://github.com/SlimPlanet/SlimFaas/blob/main/documentation/data-sets.md) - Store small, Redis-like KV payloads (cache, JSON state, flags) replicated across the cluster, with optional TTL.
- [How It Works](https://github.com/SlimPlanet/SlimFaas/blob/main/documentation/how-it-works.md) – Dive into SlimFaas’s architecture and design.
- [MCP](https://github.com/SlimPlanet/SlimFaas/blob/main/documentation/mcp.md) – Discover how to convert *any* OpenAPI definition into MCP-ready tools on the fly.
We hope SlimFaas helps you **simplify autoscaling**, **reduce costs**, and **keep your serverless workloads slim**.
---
### Community & Governance
- **CNCF Project**
SlimFaas is proud to be part of the [Cloud Native Computing Foundation (CNCF) landscape](https://landscape.cncf.io).
- **Community Meeting**
Join us through our [Community Meeting Calendar](https://calendar.google.com/calendar/embed?src=be1dd72d18650490580a7d5d96a45a6eebe0fc4c9fe8adce630754cbb6121cca%40group.calendar.google.com&ctz=Europe%2FParis)
- [ICS file](https://calendar.google.com/calendar/ical/be1dd72d18650490580a7d5d96a45a6eebe0fc4c9fe8adce630754cbb6121cca%40group.calendar.google.com/public/basic.ics)
- **Slack Channel**
Join our channel on the [CNCF Slack](https://cloud-native.slack.com/archives/C08CRC77VDE) to connect with other SlimFaas users.
- **Code of Conduct**
SlimFaas follows the [CNCF Code of Conduct](https://github.com/cncf/foundation/blob/main/code-of-conduct.md).
Enjoy SlimFaas!
---
## Adopters
List of organizations using this project in production or at stages of testing.
---
Add your logo via a pull request:
- Logo must be at PNG format, `100 px width, and 100 px height`.
- Add your logo to the `documentation/adopters` folder.
