What Is Zero-Downtime Deployment? Keeping Your App Online
Zero-downtime deployment means your app never goes offline during updates. Fly.io handles this automatically for OpenClaw.
Zero-downtime deployment is the practice of updating an application without any interruption in service. Users continue to make requests, receive responses, and experience no errors during the deployment window.
How Fly.io Achieves It
Fly.io implements zero-downtime deployments through its rolling update mechanism. When you fly deploy:
- New VMs are launched with the new image alongside existing VMs
- Fly waits for health checks to pass on new VMs
- Traffic is shifted to new VMs (old proxy connections are given time to drain)
- Old VMs are terminated only after new ones are confirmed healthy
Why It Matters for Chatbots and APIs
If your OpenClaw-powered Telegram bot is handling messages during a deploy, a downtime window means missed messages and frustrated users. Zero-downtime is essential for user-facing real-time services.
OpenClaw's Guarantees
OpenClaw deployments on Fly inherit zero-downtime automatically. The OpenClaw process itself is stateless — it reads config on startup and connects to Telegram/Discord. If the bot restarts, pending messages queue in the platform's delivery system and retry.
Configuring the Health Check
Make sure your OpenClaw app responds to Fly's HTTP health check on / with a 200. This is required for Fly to know when a new VM is ready to receive traffic.