Copy certain context keys into the HTTP responses

[ivantopo]

There is a common request for adding the trace and span ids on the HTTP responses from an instrumented service (see https://github.com/kamon-io/kamon-play/issues/16 for example). This is a common enough request that we should add it, but we need to figure out what's the cleanest way to do it.

Since #552 we will have an abstraction for instrumenting HTTP servers so, my proposal would be to add some special configuration there so that we can say "write the key span into the response, using the XXXX entry writer". This needs some more thought, looking forward for comments.

[codefromthecrypt]

works for http. I think Amazon write back the sampled status on a root span in some of their instrumentation. I wouldn't recommend putting input headers like B3 in the response as that has caused confusion in the past. Also it will lead to propagation lock in as only reason someone would put a response header is a user to access it. there is a long issue in the B3 repo about this. anyway was thinking about requiring the user to provide their own name when they want. interesting that you commonly get requests about span ID. I haven't noticed this as much as trace ID.

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On Fri, 12 Oct 2018, 21:34 Ivan Topolnjak, ***@***.***> wrote: There is a common request for adding the trace and span ids on the HTTP responses from an instrumented service (see kamon-io/kamon-play#16 <https://github.com/kamon-io/kamon-play/issues/16> for example). This is a common enough request that we should add it, but we need to figure out what's the cleanest way to do it. Since #552 <#552> we will have an abstraction for instrumenting HTTP servers so, my proposal would be to add some special configuration there so that we can say "write the key span into the response, using the XXXX entry writer". This needs some more thought, looking forward for comments. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#558>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAD61_5bTYFt3pm2i4Iuzqy4AOVYQvLRks5ukJplgaJpZM4XZfGo> .

[ivantopo]

Thanks for the feedback, @adriancole. We finally got to implement this, it was a rather quick thing to do!

[jtjeferreira]

this means kamon-io/kamon-play#29 is fixed?