[FLINK-20264] Zero-downtime / dynamic function upgrades in Stateful Functions

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: statefun-3.0.0
• Component/s: Stateful Functions
• Assignee: Tzu-Li (Gordon) Tai
• Reporter: Tzu-Li (Gordon) Tai
• Created: 20/Nov/20 16:20
• Updated: 22/Dec/20 05:39
• Resolved: 22/Dec/20 05:39

Description

Currently, due to how functions can be executed as stateless deployments separate to the StateFun runtime, they can be easily upgraded with zero-downtime.

However, up to now there are still some restrictions to what can be done without restarting StateFun processes:

• Users can not upgrade existing functions to declare new persisted state
• Users can not add new addressable (can be routed messages to it by the StateFun runtime) functions to an existing StateFun application

The end goal of this epic is to enable the above operations for function deployments, without the need to restart the StateFun runtime. Further details can be found in subtasks of this JIRA.

Sub-Tasks

• Extend invocation protocol to allow functions to indicate incomplete invocation context: Closed
• Update Python SDK to implement new invocation protocol: Closed
• Introduce function endpoint path templating in module YAML specifications: Closed
• Remove support for eager state specifications in module YAML definitions: Closed