Duplicate golang.org/x/net/trace when importing api

[jasonmf]

Describe the bug
I pull down the latest version and compile my tool which imports vault/api. My tool now immediately fails when invoked, even just using -h (from std flags):

panic: /debug/requests is already registered. You may have two independent copies of golang.org/x/net/trace in your binary, trying to maintain separate state. This may involve a vendored copy of golang.org/x/net/trace.

goroutine 1 [running]:
golang.org/x/net/trace.init.0()
        /home/me/go/src/golang.org/x/net/trace/trace.go:123 +0x1cf

I ran git bisect on the vault source and got:

170521481d58961761bfd6877221b005cf0f4c7e is the first bad commit
commit 170521481d58961761bfd6877221b005cf0f4c7e
Author: Jeff Mitchell <[email protected]>
Date:   Fri Apr 12 17:54:35 2019 -0400

    Create sdk/ and api/ submodules (#6583)

To Reproduce
Repro code (saved as /tmp/v.go):

import (
        "log"

        _ "github.com/hashicorp/vault/api"
        _ "golang.org/x/net/trace"
)

func main() {
        log.Print("Hello world!")
}

For each round of git bisect:

go run /tmp/v.go && git bisect good || git bisect bad

Output of git bisect log:

git bisect start
# good: [b5455293d4a5cc1164caf98f573d78a00cda8a72] Update deps (#6580)
git bisect good b5455293d4a5cc1164caf98f573d78a00cda8a72
# bad: [3acee2608f04e799354dc044b2b9b0e27b74ddfa] azurekeyvault doc fixed typos (#6663)
git bisect bad 3acee2608f04e799354dc044b2b9b0e27b74ddfa
# bad: [94132fd6f7e24596c8287b1ad7d9086494aaf4ed] changelog++
git bisect bad 94132fd6f7e24596c8287b1ad7d9086494aaf4ed
# bad: [1d5aeccb60aa4e2fb53145d9ce5b5eca13a4b6a2] Update protobufs, sdk changes
git bisect bad 1d5aeccb60aa4e2fb53145d9ce5b5eca13a4b6a2
# good: [797edb77545c5adfec0976a7d0c9ccb06bf48f02] dont test files in CI
git bisect good 797edb77545c5adfec0976a7d0c9ccb06bf48f02
# bad: [6388efd4f08f948249d0e4d3f905c003b75d5be8] Move useragent to sdk
git bisect bad 6388efd4f08f948249d0e4d3f905c003b75d5be8
# bad: [a4205149116d8db70eff3a315b1585d767c4da77] Update API go mod with sdk tag
git bisect bad a4205149116d8db70eff3a315b1585d767c4da77
# good: [451f2a6f36f7d14b14a218b63e90d2f2c603a9fe] Update JWT docs for bound_claims improvements (#6559)
git bisect good 451f2a6f36f7d14b14a218b63e90d2f2c603a9fe
# bad: [170521481d58961761bfd6877221b005cf0f4c7e] Create sdk/ and api/ submodules (#6583)
git bisect bad 170521481d58961761bfd6877221b005cf0f4c7e
# first bad commit: [170521481d58961761bfd6877221b005cf0f4c7e] Create sdk/ and api/ submodules (#6583)

Expected behavior
Importing both golang.org/x/net/trace and github.com/hashicorp/vault/api shouldn't cause a panic.

Environment:

• go version go1.12.1 linux/amd64
• Linux myhost 4.14.97-74.72.amzn1.x86_64 Initial Website Import #1 SMP Tue Feb 5 20:59:30 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

[ghost]

Thanks for pointing this out.
api/v1.0.2 removes a transient dependency on golang.org/x/net/trace

$ cat v.go

package main

import (
  "log"

  _ "github.com/hashicorp/vault/api"
  _ "golang.org/x/net/trace"
)

func main() {
        log.Print("Hello world!")
}

$ cat go.mod

module example.com/test

go 1.12

require (
	github.com/hashicorp/vault/api v1.0.2
	golang.org/x/net v0.0.0-20190503192946-f4e77d36d62c
)

$ go run v.go
2019/05/08 17:24:51 Hello world!

We found that the dependency on golang.org/x/net/trace was introduced by an (unneeded) dependency on google.golang.org/grpc. Since grpc is a widely used package, it might be worthwhile raising an issue with the trace package on the panic that you were seeing which is ultimately coming from here: https://github.com/golang/net/blob/master/trace/trace.go#L123