Sablier

Sablier is an open-source service that starts containerized workloads on demand and scales them to zero after periods of inactivity. It exposes an API and integrates with popular reverse proxies to intercept incoming requests, wake sleeping workloads, and (optionally) show a waiting page while the target service starts. (github.com)

Key Features

• Scale-to-zero controller that starts workloads on first request and stops them after idle time.
• Multi-provider support: Docker, Docker Swarm, Podman and Kubernetes providers.
• Integrations with reverse proxies and edge components (Traefik, Caddy, Nginx, Envoy, Istio, Apache APISIX) for request interception and wake-up flows.
• Configurable waiting pages and a "hanging request" strategy to keep clients waiting until the service is ready.
• Deployment options: official Docker images, downloadable binaries, build-from-source, and an official Helm chart for Kubernetes.
• Session and strategy APIs for programmatic control of start/stop behavior and session durations.
• Uses container labels and healthchecks to detect readiness and avoid premature routing.

(github.com)

Use Cases

• Cost and resource optimization for development, QA, or edge devices by running services only when needed.
• Self-hosted "serverless-like" behavior: automatically wake per-request services behind a reverse proxy for internal apps or demos.
• Lightweight orchestration helper for teams that need on-demand workloads without a full managed FaaS platform.

(github.com)

Sablier is focused and practical: it provides the primitives to start/stop container workloads on demand and integrates with the tooling commonly used at the edge and in clusters. It is distributed with multiple installation paths (Docker, binary, Helm) and is intended for self-hosted environments where reducing idle resource usage is desirable. (github.com)