akka/akka-core

Cluster sharding: Expose entity ID to the sharded actor

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#24,053 opened on Nov 23, 2017

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 (17 comments) (1 reaction) (0 assignees)Scala (3,547 forks)batch import
help wantednice-to-have (low-prio)t:cluster-sharding

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Description

Apologies in advance if this issue was brought up in the past. I tried to search for it, but couldn't find anything...

Currently, sharded actors don't have access to their entity identifier. The example in the docs uses self.path.name, but that is URL-encoded and not the actual ID. On top of that, this seems to be an implementation detail - the encoded ID happens to be what the shard uses for the actor name. At the same time, it is obvious that adding an Actor.entityId method is not a good solution (actors don't know whether or not they're sharded).

So I suggest modifying the ClusterSharding.start (or adding another API next to it) so that instead of taking Props as a parameter, it would take a String => Props function that would get invoked with the entity ID. What do you think?

(Of course, I wouldn't mind doing a PR for it, if there's interest)

Contributor guide

Research direction
Implement a new overload of ClusterSharding.start that accepts a function from entity ID to Props, and modify the sharding code to pass the entity ID to the actor creation.
Tech stack
scala
Domain
backendapiinfrastructure
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
scala
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70