Grpc-web: undefined: transport.StreamFromContext

[gertcuykens]

% go get -u github.com/improbable-eng/grpc-web/go/grpcwebproxy
# github.com/mwitkow/grpc-proxy/proxy
go/src/github.com/mwitkow/grpc-proxy/proxy/handler.go:63:30: undefined: transport.StreamFromContext
% 

[johanbrandhorst]

This was removed in a recent commit to grpc-go. See https://github.com/grpc/grpc-go/pull/1904#issuecomment-372087340. Apparently this API should not be used by external packages.

[easyCZ]

What is the sequence of steps that results in this problem? When building the project, I cannot reproduce the error outlined here.

[gertcuykens]

Just go get -u github.com/improbable-eng/grpc-web/go/grpcwebproxy I think you have the old grpc-go lib already installed?

[gertcuykens]

Maybe the problem is grpc-go itself and you happen the have the last working version?

% go get -u google.golang.org/grpc
% go get -u github.com/grpc/grpc-go
package github.com/grpc/grpc-go: code in directory /Users/gert/go/src/github.com/grpc/grpc-go expects import "google.golang.org/grpc"
% 

[easyCZ]

Reproduced now. Had to delete my existing grpc-web to trigger it. This is a problem in a downstream dependency. Will investigate.

The dependencies of grpc-web are vendored so we should be able to use them directly without the impact of the grpc change. Cloning the repo directly or using dep should work

[johanbrandhorst]

This is reproducable with a recent version of gRPC, so this repo needs to fix the use of a deprecated function _or_ ensure that gRPC versions are constrained to below 1.11. I'm in favor of the former, if possible.

[johanbrandhorst]

I think if https://github.com/grpc/grpc-go/issues/2016 gets implemented this should be a fairly straightforward fix.

[ravihugo]

Is there a work-around or are we pretty much waiting for grpc-go at this point?

[johanbrandhorst]

Use an older version of gRPC is the workaround.

[johanbrandhorst]

https://github.com/grpc/grpc-go/issues/2016 might mean we can incorporate a fix for this here now.

[jheinnic]

I just bumped into this issue as well this afternoon. I found a quick and dirty work-around that I thought I'd share in case anyone else is sufficiently blocked and/or impatient to make use of such until a genuine fix is incorporated.

After failing to "go get" grpcwebproxy with the transport.StreamFromContext undefined error message, I cd into my GOPATH's staged copy of grpc-go:

cd $GOPATH/src/google.golang.org/grpc

There is a tag for the v1.10.1 release, the last one before this artifact was removed. I first tried simply checking out that tag...

git checkout v1.10.1

...but when I tried "go get" for grpcwebproxy in this state, the build failed with a complaint about that the google repository not being at the HEAD of master. I'm not planning on pushing this staging area back (I hope I wouldn't have sufficient permissions to do so if I tried, but I'm not about to try it and see all the same), so I attempted a soft reset back to master with the content of v1.10.1 still in my workspace, then committed the deltas I'd carried over.

git reset --soft master
git commit -m 'Hack Back to v1.10.1 - DO NOT PUSH'

At this point, I was able to "go get" grpcwebproxy successfully. Go did not seem to care that my staged branch was one commit ahead of origin.

[ryanjaeb]

Using dep works for me. I posted my notes for building a Docker image if anyone is looking for a temporary option that's easy to get running. I haven't used it for anything more than a bit of playing around, so use it at your own risk.

[pieterlouw]

grpc-proxy requires a small change in it's handler.go file to be compatible with the latest grpc-go.(There's also a PR for that).

[proposal]grpc-proxy is a small project and dependency - it might be worthwhile merging it into this project as a sub package, for example: improbable-eng/grpc-web/go/proxy. (this is what I was basically forced to do with caddy-grpc until the PR is merged ).

By doing that you can change the handler.go to be compatible with upstream grpc-go by implementing a change similar to the following: https://github.com/pieterlouw/caddy-grpc/blob/master/proxy/handler.go#L69-72

Also, by adding it to this project then it means this project is not dependent on grpc-proxy what appears to be a stale project at the moment.

[trusktr]

For anyone stumbling here, this commit perfectly describes how to fix undefined: transport.StreamFromContext (or why there's no bin file after go install): https://github.com/jfyne/docker-grpcwebproxy/commit/da712301bde103014e7becbac0fa298384bf622f

For example, I had this problem with http://github.com/improbable-eng/grpc-web, and the following worked:

go get -u github.com/improbable-eng/grpc-web/go/grpcwebproxy
cd $GOPATH/src/github.com/improbable-eng/grpc-web
brew install dep # install golang/dep somehow
dep ensure
go get -u github.com/improbable-eng/grpc-web/go/grpcwebproxy

After that $GOPATH/bin/grpcwebproxy was available.

[johanbrandhorst]

It seems this is no longer a problem with the vendored version of gRPC