Customize RestTemplateBuilder

[bedla]

Hi,
I found that it would be handy to customize RestTemplateBuilder created by auto-configuration. It has some useful method that sometimes I want to call. Currently I have to use bean post processor to customize it - I think that it is ugly and error prone.
What do you think about this proposal?
Thx
Ivos

[bedla]

there is lots of java.io.IOException: No space left on device errors in build log. could somebody fix CI?

[bedla]

@wilkinsona sorry for disturbing but I found that you mentioned at comment #22885 (comment) that CI failures are general problem. Mine PR fails at No space left on device as mentioned above... is it same problem and will be fixed?

[philwebb]

@bedla Sorry about the CI failures. We had some issues yesterday.

[philwebb]

Flagging for team attention to see what the rest of the team think about the proposal. I'm a little concerned that the immutable nature of RestTemplateBuilder makes the Customizer slightly unusual. I think most of our existing ones have a void return and expect the customizable thing to be mutable.

Perhaps we need a different name for it. Another option might be have an optional RestTemplateBuilderFactory that's used to create the initial instance.

@bedla out of interest, which RestTemplateBuilder methods do you typically want to customize?

[bedla]

Yep, that name is bit unusal as you mentioned, but I cannot imagine something more suitable.

My usecase is that I wan to use all the stuff (otherwise I have to copy-paste it) from auto-configuration (see RestTemplateAutoConfiguration#restTemplateBuilder method) and mainly call methods setBufferRequestBody, setConnectTimeout and setReadTimeout (sometimes defaultHeader).

I am open to any suggestion.

[snicoll]

Thanks for the PR @bedla and the follow-up. I am personally not super keen on the idea of the customizer. We discussed this at our team meeting a couple of weeks ago and I mentioned a similar pattern we use to further tune message listener container factories.

I've pushed some code that mimics that pattern for RestTemplateBuilder, see snicoll@0d06a84

One downside with this approach is that we expose an additional bean for the purpose of customization. I wish we could provide a more efficient option. Anyway, foo for thoughts @philwebb

[bedla]

@snicoll no problem, I am happy to help. Anyways I have checked commit you mentioned and maybe I am missing something, but I am still unable to customize that builder, right?
Those setBufferRequestBody, setConnectTimeout and setReadTimeout (sometimes defaultHeader) are interesting for me.

[snicoll]

This test showcases that exact use case unless I am missing something: snicoll@0d06a84#diff-cfe5e8d68c724e41762c869df2ddaec6R241

[bedla]

ahh, I see. Thx, Ivos

[snicoll]

@bedla thank you for the suggestion and the PR. We've discussed that at our team meeting and we've decided to give my proposal a go. I am going to close this PR now, please follow-up on #23389