WithHealthzEndpoint should answer with application/json Content-Type

[GreyXor]

🐛 Bug Report

WithHealthzEndpoint didn't set Content-Type to anything but text/plain; charset=utf-8. Shouldn't it be application/json?

To Reproduce

1. Enable WithHealthzEndpoint
2. GET to the /healthz endpoint

Expected behavior

Content-Type: application/json
Grpc-Metadata-Content-Type: application/grpc

Actual Behavior

Content-Type: text/plain; charset=utf-8

Your Environment

Go 1.18 with grpc-gateway v2.10.0
Linux 5.17.0-arch1-1 #1 SMP PREEMPT Tue, 22 Mar 2022 23:36:09 +0000 x86_64 GNU/Linux

[johanbrandhorst]

Yeah this definitely seems reasonable. Would you like to contribute this fix?

[johanbrandhorst]

CC @brumhard @antonioiubatti93

[GreyXor]

Yeah this definitely seems reasonable. Would you like to contribute this fix?

Sure, but i don't know where to define headers. I never looked at the code of grpc-gateway. I'll be looking at

[GreyXor]

Since we stay in the WithHealthEndpointAt() method and we use the outgoing marshaler directly in it, we can't take advantage of the Content-Type deduction (except in the errorHandler). In my opinion it is easier in this case to directly add the headers before writing the response writer.

I invite you to review my PR with the proposed changes. I'm listening to your comments