Fix gRPC and bidirectional examples' code generation instructions

[2rs2ts]

Hello! My teammates and I were trying to get the grpc example to work, and were eventually able to figure out the things that needed to change to make its instructions, which seem to be around six years old, work with modern versions of protoc and the related Golang tooling for it. We decided that not only should we update the .proto file and generated code, we should also make sure that the two separate generated files (since there are two now, rather than one) get committed. In addition to that, we recorded some details in the README about how to find the versions of the software used to generate the code, for newbies to the codebase (like ourselves!) who didn't really know what was assumed about the development environment.

The updates to the client required us to also regenerate the Python plugin code, so we updated that and made sure we spelled out the dependencies that were used for that language. We found that we did have to manually re-insert the copyright notices to the python code, but not the Golang code; if there's an option in the generation command that fixes that, then we'd love to know about it.

We felt that recording the versions of various software dependencies used would not only help orient new users, but it would also make it easier in the future, if protoc or related tools introduce more breaking changes, to figure out what needs to change to make the instructions keep working. This is our first time using both this plugin repo and gRPC in general, and we're not experts with Golang either, so it may read as unnecessarily redundant information to an experienced developer, so we apologize for that. Also, we may not have written idiomatic code, but we're happy to take feedback and make sure it is idiomatic.

While we were at it, we also made the net/rpc example that lived in the grpc example's folder work. Before, it would fail with an error from rpc_server.go saying that it couldn't find the (hardcoded) kv_grpc plugin, which makes sense since the net/rpc plugin doesn't define that for obvious reasons.

And we also updated the bidirectional example since it's similar to the grpc example, plus we tested the other examples to ensure they still work, particularly the negotiated example which re-uses the grpc example's code. They all work on our machine, so hopefully they all work for you too.

Now, probably the most important change here is not to the example, but rather the top-level go.mod dependencies. The thing is, we were struggling to get things to work unless we upgraded the gRPC and protobuf dependencies to match modern guides (such as this one on grpc.io) unless we updated those dependencies. We were really hesitant to proceed until we noticed that the terraform-plugin-go repo uses the same grpc version and even a much more recent protobuf version, and if that repo is supposed to serve as a template or guide for people writing terraform plugins, and it's pretty married to gRPC, then upgrading would probably be fine. Also, our new generation instructions are based not only on those modern guides, but also how that repo generates its code too, so we felt pretty justified in our decisions after that. With that said, we understand that this repo is a dependency for many Hashicorp projects, so we're not sure whether we actually can upgrade those dependencies. Please let us know if we need to find a set of dependencies that will work for all consumers of this project.

At any rate, this fixes #249.

[hashicorp-cla]

All committers have signed the CLA.

[2rs2ts]

Please accept my apologies about the delay in signing the CLA. I did not realize I had not already signed the CLA a long time ago, and I'm checking with my employer's legal department to make sure it's ok for me to sign it.

[2rs2ts]

I got approval to sign from my employer. I am surprised that the bot does not require the commit co-authors to also sign, but I'll ask them to do it too.

Edit: we have all signed the CLA, so we should be good to go.

[heaxo]

Unknown flag: --go-grpc_opt

[2rs2ts]

@heaxo you might have an out of date version of protoc or the golang/grpc plugins for it. While I used slightly newer versions of the libraries from this guide than are printed here (as you can tell from the generated code), I do believe the versions from here will also work: https://grpc.io/docs/languages/go/quickstart/

[2rs2ts]

@tomhjp is my PR obsoleted by #286? I haven't had time to look deeply into it, but I'd be happy to close my PR if you can confirm

[tomhjp]

Hey @2rs2ts - I think you're right that most of this is obsoleted by #286, sorry about that and the delay responding. Comparing against main, it does look like your fix for the net/rpc example within grpc could still be landed, as it still looks broken to me on main. If you did want to land it, you could rebase the PR down to that change, but unfortunately I won't be help land that as I'll be losing write access to this repo later today. Thank you for the PR though! ❤️

[2rs2ts]

It's been too long, and I don't remember a whole lot, but it seems that the new generation process would necessitate me starting from scratch, and I'd have to rewrite the PR summary. At that point, why even bother saving this branch? Hopefully this PR will be of some use to someone who does want to re-update the example for net/rpc. (We were not using it, we just made sure that if we were going to change one thing, we'd keep it all consistent...)