grpc middleware: support to add additional tags to a GRPC ClientHandler

[fho]

I would like to add additional fixed tags per GRPC ClientHandler to spans like "component = grpc".

A way to implement it could be to introduce an additional ClientOption to the grpc package to pass tags when calling NewClientHandler().
Similiar to https://github.com/openzipkin/zipkin-go/blob/master/middleware/http/client.go#L60

[codefromthecrypt]

just to know about existing practice. on the java side we have "parsing callbacks" which allow people to add whatever. doing more generically can prevent whack-a-mole changes later, as we all want the api to be stable as possible. ex https://github.com/openzipkin/brave/blob/master/instrumentation/grpc/src/main/java/brave/grpc/GrpcClientParser.java

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On Mon, Aug 12, 2019 at 6:30 PM José Carlos Chávez ***@***.***> wrote: Yes, exactly that. Up for a PR? — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#143?email_source=notifications&email_token=AAAPVVZNPAYJLGMTSP7Z4JDQEE3TPA5CNFSM4IK7YMDKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOD4CEE2A#issuecomment-520372840>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAAPVVYH7DRNWY6IANYCSC3QEE3TPANCNFSM4IK7YMDA> .

[codefromthecrypt]

also another option. if this is static.. with a span finished handler you can add another tag. ex as long as grpc client adds grpc.method tag you could look for that tag and add your other one. this approach would work for any other tag based on another

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On Mon, Aug 12, 2019, 6:32 PM Adrian Cole ***@***.***> wrote: just to know about existing practice. on the java side we have "parsing callbacks" which allow people to add whatever. doing more generically can prevent whack-a-mole changes later, as we all want the api to be stable as possible. ex https://github.com/openzipkin/brave/blob/master/instrumentation/grpc/src/main/java/brave/grpc/GrpcClientParser.java On Mon, Aug 12, 2019 at 6:30 PM José Carlos Chávez < ***@***.***> wrote: > Yes, exactly that. Up for a PR? > > — > You are receiving this because you are subscribed to this thread. > Reply to this email directly, view it on GitHub > <#143?email_source=notifications&email_token=AAAPVVZNPAYJLGMTSP7Z4JDQEE3TPA5CNFSM4IK7YMDKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOD4CEE2A#issuecomment-520372840>, > or mute the thread > <https://github.com/notifications/unsubscribe-auth/AAAPVVYH7DRNWY6IANYCSC3QEE3TPANCNFSM4IK7YMDA> > . >

[jcchavezs]

I am creating an example on this. Hold on for news.

[jcchavezs]

@fho FYI #177