[transitive dependency] netty update from vertx 5.0.8 includes a hidden breaking change

[Fabilin]

Version

5.0.8

Context

Not exactly an issue with Vert.x itself, but the update from 5.0.7 to 5.0.8 includes a netty update to 4.2.x which has a binary incompatibility with previous versions that may otherwise exist in a project (in our case, because of AWS SDK). More specifically, io.netty:netty-codec:4.1.x was split into many artifacts in version 4.2.0, which can lead to build tools like Maven and Gradle loading the artifacts for both versions at the same time.

In our project, this resulted in a rather hard to diagnose issue with the two versions of netty existing simultaneously causing runtime errors that end up swallowed by netty/vertx.

It could therefore save developers some time to amend the changelog and/or the wiki page for the 5.0.8 update to make a note of this possible breaking change.

Steps to reproduce

No response

Do you have a reproducer?

No response

[vietj]

can you point out which breaking change in Netty it was ?

[Fabilin]

In our case our issue was specifically caused by this change:

The netty-codec module has been split into a number of different sub-modules, which the netty-codec module then depends on. In other words, netty-codec is now multiple jar files instead of one.

https://github.com/netty/netty/wiki/Netty-4.2-Migration-Guide

Edit: I reckon it may be enough for Vert.x to mention the Netty update, highlight the potential transitive dependency incompatibility if other dependencies pull netty-codec, and link to the above migration guide for further information

[vietj]

you mentioned 5.0.7 to 5.0.8 , what specifically changed in the upgrade for Netty ?

[Fabilin]

Not sure I understand the question, but unless I am mistaken it was version 5.0.8 of vertx which contained the update of netty to version 4.2, which in turn caused transitive dependency clash with netty-codec:4.1.+ and the split modules netty-codec-*:4.2.+