Consumer Source with relative offset definitions

[2m]

There has been a need to query certain Kafka topics with relative offsets, for example last offset, or last offset minus 100, or last offset minus 10 minutes.

Currently it is possible to do this by using metadata API to query for offsets and manually deriving an offset for which a source should be created. This could be made simpler by abstracting such logic in a user-friendly consumer source factory.

[2m]

/cc @agemooij @RayRoestenburg

[jewertow]

I would be very happy if I could take care of it. It will be my first contribution to alpakka-kafka, so maybe could you give me some more suggestion or could you explain me what do you exactly expect from user-friendly consumer source factory? Otherwise I could suggest implementation.

[ennru]

I believe this would be best implemented as something that retrieves the current offset and creates subscriptions from those offsets.
This would benefit from implementing #765 first, I guess.