Explore object storage as alternative to MongoDB+GridFS

[eddybl]

As far as I can see, the MongoDB+GridFS is used only for attachment handling in Olog.

As we currently do not use MongoDB in our infrastructure, we would like to explore alternatives to that, for example an object storage.
If something like this was ever considered or explored, we would be interested in feedback or opinions on that idea.

Otherwise we will most likely just try it out... as a drop-in replacement the effort looked reasonable (after only a quick glance at the code).
If it works well and we are happy with that we would then probably look into adding it as an configurable feature

[smarsching]

If the implementation is pluggable, an obvious alternative to both MongoDB and an object storage would be use of the local filesystem. This could significantly simplify deployments where there only is a single server anyway, as it would completely remove the necessity of deploying a separate service. I think that, once the code is made pluggable, writing an implementation that is backed by the local filesystem should be trivial.

[georgweiss]

While the Spring CrudRepository is agnostic with respect to the underlying storage implementation, the Olog service would need some refactoring to handle alternative CrudRepository implementations over SPI.