Zipkin 2.12.6

Zipkin 2.12.6 migrates to the Armeria http engine. We also move to Distroless to use JRE 11 in our docker images.

Interest in Armeria 3 years ago originated at LINE, a long time supporter of Zipkin. This was around its competency in http/2 and asynchronous i/o. Back then, we were shifting towards a more modular server so that they could create their own. Over time, interest and our use case for Armeria grown. Notably, @ewhauser has led an interest in a gRPC endpoint for zipkin. Typically, people present different listen ports for gRPC, but Armeria allows the same engine to be used for both usual web requests and also gRPC. Moreover, now more than ever LINE, the team behind Armeria are involved deeply in our community, as are former LINE engineers like @anuraaga. So, we had a match of both supply and demand for the technology.

End users will see no difference in Zipkin after we replaced the http engine. Observant administrators will notice some of the console lines being a bit different. The whole experience has been drop-in thanks to spring boot integration efforts led by @anuraaga @trustin and @hyangtack. For those interested in the technology for their own apps, please check out Armeria's example repository.

There's more to making things like http/2 work well than the server framework code. For example, there is nuance around OpenSSL which isn't solved well until newer runtimes. For a long time, we used alpine JRE 1.8 because some users were, justifiably or not, very concerned about the size of our docker image. As years passed, we kept hitting fragile setup concerns around OpenSSL. This would play out as bad releases of stackdriver integration, as that used gRPC. As we owe more service to users than perceptions around dist sizes, we decided it appropriate to move a larger, but still slim distroless JRE 11 image.

The MVP of all of this is @anuraaga, the same person who made an armeria zipkin server at LINE 3 years ago, who today backfilled functionality where needed, and addressed the docker side of things. Now, you can use this more advanced technology without thinking. Thank you, Rag!