Use jackson-jr where possible

[driverpt]

Is your feature request related to a problem? Please describe.
Coldstarts in Lambda

Describe the solution you'd like
Use of jackson-jr for faster startup time

Describe alternatives you've considered
N/A

Additional context
It's recommended by AWS the usage of jackson-jr where possible in the Documentation

[pankajagrawal16]

Thanks for opening this issue @driverpt. It will definitely be great to use jackson-jr instead. As of now, there will be other libraries which which end up importing jackson anyways, but if powertools itself can stop using it, is something definitely worth evaluating.

[driverpt]

Can't we just include a shaded copy of Jackson JR instead of having External Dependency? Similar to what was already done in AWS SDK for Java V2 ?

[Neuw84]

Hi,
I would like to contribute to the project. Quite good experience with Java and Lambda specifically from my previous role.
Could I work on this?

[jeromevdl]

@Neuw84 Did you have a look at this? I'm interested to know what could be done here. As we already have moving stuff on metrics (#944) and logging (#965), that will cause breaking changes and imply a v2, maybe it's an opportunity to also look at the serialization fwk... But as mentioned by @pankajagrawal16, other libraries are importing jackson, so we would end up with more libraries in the end...

[msailes]

Which other libraries are we thinking off?

The managed runtimes uses Jackson, but they change the package name of it, so I don't think we should consider that.

[jeromevdl]

I thought the log4j json layout library was using jackson, but no. It's worth having a deeper analysis, but maybe I'm wrong... (would be great).

[jeromevdl]

After analysis, several libraries are using jackson-databind:

• aws-java-sdk-core and jmespath-java, both used in x-ray (tracing module)
• aws-embedded-metrics (metrics module)

We could get rid of it and use something else in powertools but it would lead to an additional library then, and bigger jars, bigger cold starts...

[jeromevdl]

wont fix as other libraries are using heavier versions of jackson (see above), and we cannot embark a new library