Feature: Instance removal

Picodata should provide a user-friendly way to remove an instance from a cluster.

When an instance is down it is hard to automatically determine if the instance is unavailable temporarily or if it is lost forever. Therefore instance deletion should be triggered manually by an admin command.

API

Lua: picodata.remove_instance(instance_id)

The implementation should be done in Rust, the Lua API should only proxy calls to Rust.

CLI:

picodata --address ADDR rm instance <instance_id>
picodata -a ADDR rm i <instance_id>

where ADDR is an address of any instance of the cluster

Behavior

The procedure of an instance removal is the following:

1. Bring the instance down.
2. Execute the instance removal command.

If the instance removal command is issued while the instance is running, an error should be raised.

DoD

• The API is implemented
• CLI command
• Integration test
• The docs website contains a brief description of the feature usage.

Motivation

Instance removal is a basic functionality required for production usage. An instance removal is needed when, for example, a server where the instance is running is decommissioned.

changed milestone to %Picodata 2023-06

added 1 deleted label

changed milestone to %Release 0.2 - Sharding MVP

стоит добавить аргумент --cluster-id

assigned to @vs

mentioned in merge request !209 (merged)

При удалении происходят изменения (должны происходить, т.к. это план к реализации):

• на стороне кластера: из raft_group удаляется запись о ноде
• на стороне ноды: деактивируется, останавливается. Опционально отмечается как expelled чтобы больше не стучалась в кластер. В данный момент нода стучится в кластер, но кластер её не принимает. Предполагается, что деактивация и грейсфул шатдаун в совокупности сделают необходимые изменения и в cluster-wide спейсах, и в replicaset-спейсах.

Теоретически нет причин не бутстрапнуть чистую ноду с айдишником ранее заэкспелленой ноды.

marked the checklist item CLI command as completed

marked the checklist item Integration test as completed

marked the checklist item The docs website contains a brief description of the feature usage. as completed

marked the checklist item The API is implemented as completed

closed with merge request !209 (merged)

mentioned in merge request docs!40 (merged)