Spring Boot Actuator dependency on Jackson prevents usage of GSON

[laurikimmel]

According to Spring Boot 1.2.0 release notes all Jackson libraries has to be excluded from the classpath to use GSON for creating JSON output. This is not possible in case application is using spring-boot-starter-actuator.

Excluding jackson-core, jackson-databind and jackson-annotations from spring-boot-starter-actuator will result with BeanCreationException:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'configurationPropertiesReportEndpoint' defined in class path resource [org/springframework/boot/actuate/autoconfigure/EndpointAutoConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.boot.actuate.endpoint.ConfigurationPropertiesReportEndpoint]: Factory method 'configurationPropertiesReportEndpoint' threw exception; nested exception is java.lang.NoClassDefFoundError: com/fasterxml/jackson/databind/AnnotationIntrospector

And the application is not able to start.

It turns out spring-boot-starter-actuator needs all three mentioned Jackson libraries to start properly. Once Jackson libraries are included in the classpath GSON is not used to produce JSON output any more.

[snicoll]

I don't think that's what the release notes is saying. Are you trying to use GSON for everything or your own services only?

[laurikimmel]

Spring Boot 1.2 Release Notes:

It is now possible to use GSON instead of Jackson to create JSON output. If you use GSON you should exclude Jackson libraries from your Maven/Gradle build. Jackson remains the default and recommended choice.

I was investigating how to use GSON for my own services. Release notes where only documentation I was able to find about Spring Boot and GSON support.

[philwebb]

Looks like this one might be a little tricky to fix. The easiest solution for now might be for us to disable that endpoint if Jackson is missing or find some way to allow them to co-exist.

[snicoll]

My point was that the release notes are only about what Boot uses internally. You can still configure and use Gson if that's what you want to do.

[dsyer]

I guess we need a way to tell the autoconfigurers that even if they find Jackson and GSON, we prefer GSON. I think the user can always create converters and assign an order using HttpMessageConverters though, so there isn't anything stopping you from using GSON (hence I don't think this is a bug).

[philwebb]

Reopening to consider comments in commit d718a80

[balajeetm]

Is there a way to use Gson only for specific classes - mainly (JsonElement, JsonObject, JsonArray) and for the rest use Jackson. JsonElement is not a plain pojo, hence jackson has trouble serialising it. Would be good if we can use both or if actuator can work with Gson. How should we go about it?

[philwebb]

@balajeetm This issue has been closed for a while. If you've got additional questions please ask on stackoverflow.com. Thanks!