zalando
Spring boot 4 migration
Description
This pull request completes the Spring Boot 4 and Spring 7 migration for the Logbook project, bringing the entire codebase to the latest Spring ecosystem versions.
This is a BREAKING CHANGE because Logbook from this version will only support java 17 and higher. With this, support of spring boot 2.x will be discontinued.
Motivation and Context
Spring Boot 4.0.0 was released on 20.11.2025. This PR is aimed to allow Logbook clients to effortlessly migrate to the new Spring versions.
This PR is done based on https://github.com/zalando/logbook/pull/2146 (all the credits go to @bcaillard) Linked issues: https://github.com/zalando/logbook/issues/2177,
Types of changes
- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [X] Breaking change (fix or feature that would cause existing functionality to change)
Checklist:
- [X] My change requires a change to the documentation.
- [X] I have updated the documentation accordingly.
- [X] I have added tests to cover my changes.
- [X] All commits are signed
Is it possible to use Jackson 3 as Spring migration guide recommends. com.fasterxml.jackson.databind.ObjectMapper does not exist in Jackson 3, so the LogbookAutoConfiguration is not migrated properly.
That's a fair callout. We'd like to keep the compatibility with Jackson 2 as well. Would need to experiment a bit to understand how to make it work for both types of clients, as even Spring Boot 4 will keep the support with Jackson 2. I may open a separate PR for this piece
Do you have any planned release date for spring boot 4 compatibility? Migrating to spring boot 4 fails due to logbook deprecated api usage (org.springframework.boot.autoconfigure.web.reactive.function.client.ReactorNettyHttpClientMapper). Waiting for you guys for spring migration :)
We still have a couple of things to figure out, but I think we could do an RC release this week arleady with this PR, and we'll do another RC with jackson related fixes (and then more depending on how many issues we'll find on the way before we do the actual 4.0).