Stateful WebSocket scale-in without drain

warningstateful-websocket-scale-in-without-drain

Scaling a gateway down kills every live WebSocket on the removed instance at once. Without a drain step those clients all reconnect together.

Severity: warning
Selects: every node of kind realtime-gateway
Components in scope: 20

What it checks

It looks at every node of kind realtime-gateway, and fires when:

— all of these hold:
— the node's `autoscaling` is true
— the node's `drainOnScaleIn` is false

Message

Realtime gateway '{{node.id}}' autoscales but does not drain connections on scale-in. Every scale-down becomes a reconnect storm.

{{node.id}} style paths are filled in from the node, the edge or the design the finding is about.

Applies to · 20 components

Real-time gateway realtime-gateway

Tripped by · 10

Reference designs whose broken twin names this rule in its header. The gate reads the same header, and fails when a rule no design trips.

discord-messagesreference distributed-emailreference facebook-messengerreference figma-multiplayerreference linear-syncreference nearby-friendsreference slack-messagingreference spotify-playbackreference twitch-livereference whatsapp-messagingreference

Source

1# yaml-language-server: $schema=../schema/rule.schema.json
2# Autoscaling down a gateway that holds live WebSockets kills every connection on the
3# removed instance at once. Without a drain step the clients all reconnect together.
4# Tripped by: designs/slack-messaging.broken.yaml
5schemaVersion: "1"
6type: "rule"
7id: "stateful-websocket-scale-in-without-drain"
8severity: "warning"
9select:
10  node:
11    kind: "realtime-gateway"
12when:
13  all:
14    - prop: "autoscaling"
15      equals: true
16    - prop: "drainOnScaleIn"
17      equals: false
18message: "Realtime gateway '{{node.id}}' autoscales but does not drain connections on scale-in. Every scale-down becomes a reconnect storm."

The same page as markdown, for an agent: /catalogue/rules/stateful-websocket-scale-in-without-drain.md