missing required module 'CgRPC'

[alqa-dash]

Hi!

I want to clarify CgRPC integration process for myself. I looked through threads here and didn't find anything useful.

I get whole SwiftGRPC project into my workspace and configure headers and Linked Frameworks. This way everything is fine.

But in my case I have to create framework which uses SwiftGRPC as a dependency framework and share it with another team. To use that custom framework they must add custom framework to Linked Framework as well as SwiftGRPC, BoringSSL, CgRPC, SwiftProtobuf. It would be ok but this is not the end of story. Additionally they should configure Header Search Paths for CgRPC include folder and copy frameworks in Build Phases. Huh.. Now it should work. Without these steps they got "missing required module 'CgRPC'" and so on.

My question: is it possible to avoid configuring Header Search Paths and (perhaps) copying frameworks?

[JonasVautherin]

I am wondering the same thing, I believe. So if I understand correctly, you are trying the "manual integration", right?

I personally build manually in command line, with something like:

1. Clone the git repo
2. Run make && make project
3. Run something like xcodebuild -target BoringSSL -target SwiftGRPC -target SwiftProtobuf -target CgRPC ...

I end up with all four frameworks, but when I include them, CgRPC is not recognized as a module (same as you, I believe).

My solution is to create a Modules/ and Headers/ directory inside the built CgRPC.framework, copy cgrpc.h into Headers/ and create the following modulemap in Modules/ (notice the framework keyword):

framework module CgRPC {
    header "cgrpc.h"
    export *
}

I believe that I am doing manually what you do from Xcode (i.e. configuring Header Search Paths etc).

@MrMage: Would you have a comment on that? I must say I am not familiar with Xcode projects, so I mainly solved my issue through trial-and-error. So I'd like to have your opinion about what you think is happening and if that could be solved upstream.

Note that integrating through Cocoapods works flawlessly.

[MrMage]

No idea about this, sorry. What is the error when the header is not included? In theory, https://github.com/grpc/grpc-swift/blob/master/Sources/CgRPC/include/module.modulemap should take care of this, but maybe it's missing something. Also, could you check in the Xcode build output whether it uses https://github.com/grpc/grpc-swift/blob/master/Sources/CgRPC/include/module.modulemap or auto-generates a custom module map? Took me a while to get this right for https://github.com/MrMage/zstd/blob/swift-master/lib/include/module.modulemap, for example.

[alqa-dash]

@JonasVautherin, thank you for you suggestion. I'm going to test it soon.

@MrMage, If header is not included the error is ":0: error: missing required module 'CgRPC'". Unfortunately, Xcode build output does not have anything about modulemap at all.

[MrMage]

@alqa-dash where does that error come up? For now, it would probably make more sense to try Jonas's suggestions first, though.

[alqa-dash]

@MrMage this error appears just right when compilation starts. I will try Jonas's advice.

I have one more question, sorry for offtopic: how can I implement grpc upload in background mode in case grpc is implemented in framework (not the application code)? E.g. customer has to upload large file and don't want to wait for its completion with application on screen?

[MrMage]

Unfortunately I have no experience with the that. Given that SwiftGRPC does not use NSURLSession, SwiftGRPC background downloads might not be right now; i.e. you might need to ask iOS to create a background task for you. But those tasks are limited to 10 minutes I think.

This should get better once there is a SwiftNIO+Network.framework-based variant of SwiftGRPC, but that's still a while out.

[alqa-dash]

Ok, I think, I can manage background mode. But there is another issue (or may be I don't know how to cook it). When I enable network throttling and set bad connection settings and try to send file, I see that couple of packets have been transmitted successfully but then I got "[TCP Previous segment not captured] and that's it. Client stops sending anything. Is it possible to address this issue?

[MrMage]

No idea. It doesn't belong in this thread, either, I think. You might want to create a simple test case with the Objective-C GRPC client library and compare results. If that one fails as well, it might make sense to ask on the gRPC-Core mailing list instead.

…

On 24. Jul 2018, at 16:05, alqa-dash ***@***.***> wrote: Ok, I think, I can manage background mode. But there is another issue (or may be I don't know how to cook it). When I enable network throttling and set bad connection settings and try to send file, I see that couple of packets have been transmitted successfully but then I got "[TCP Previous segment not captured] and that's it. Client stops sending anything. Is it possible to address this issue? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub, or mute the thread.

[allezxandre]

I'm having the same issue about CgRPC being a 'missing required module'. Any guidance?

I know absolutely nothing about Clang, so I just looked up the documentation and I'm probably wrong, but shouldn't
https://github.com/grpc/grpc-swift/blob/master/Sources/CgRPC/include/module.modulemap include the framework keyword?

[JonasVautherin]

@allezxandre: I don't know if it should or not, but my fix is to add it, as explained in this comment above :-). And I still have to answer @MrMage questions from here, but haven't taken the time yet. Feel free to have a look!

[JonasVautherin]

So just for the record, here is how I build grpc for iOS manually (tag 0.4.2, for some reason). I have this script for people who don't use Cocoapods, but Carthage support (#282, #284) will make it easier to build grpc for iOS.

Note lines 31-40, where I fix this very issue manually. I am trying to understand how that can be fixed properly in the build system.

[JonasVautherin]

@MrMage: Some more feedback. So I build CgRPC.framework, and I get the following:

CgRPC.framework/
    ├── CgRPC
    └── Info.plist

Which results in the following build error (camera.grpc.swift is generated with protoc):

/camera.grpc.swift:25:8: Missing required module 'CgRPC'

When I copy module.modulemap into CgRPC.framework/Modules:

CgRPC.framework/
    ├── CgRPC
    ├── Info.plist
    └── Modules
        └── module.modulemap

I get:

CgRPC.framework/Modules/module.modulemap:2:12: error: header 'cgrpc.h' not found
error: could not build Objective-C module 'CgRPC'

If I now copy cgrpc.h into CgRPC.framework/Headers:

CgRPC.framework/
    ├── CgRPC
    ├── Headers
    │   └── cgrpc.h
    ├── Info.plist
    └── Modules
        └── module.modulemap

I get the exact same error as above, just as if the module.modulemap had no effect at all.

And finally, if I add the framework keyword into module.modulemap, as suggested in my fix above and also by @allezxandre, the build succeeds.

So it seems like all three changes are needed:

1. Copy cgrpc.h into CgRPC.framework/Headers
2. Copy module.modulemap into CgRPC.framework/Modules
3. Add the framework keyword to module.modulemap

One more interesting thing: if I add the framework keyword directly into Sources/CgRPC/include/module.modulemap and try to build CgRPC.framework, it fails because... header 'cgrpc.h' not found (whereas in the current master it builds, but fails when linking the framework in another project).