gRPC [Golang] Master Class: Build Modern API & Microservices | Udemy

Overview

This repo has been created during doing this gRPC course on Udemy.

The greet and blog app I did together with the instructor.
The calculator app I did mostly on my own. (Of course at the end I checked the solution and fixed mine if it was needed).
In Section 9 - Advanced features there are errors, deadlines/timeouts, SSL and reflection that I did along with the instructor and affected calculator as well as greet.

After the course I added:

• Example interceptor to the greet server ()
• Example tests to the greet app
• Bit of extra information about how to use Evans CLI / grpcURL with (m)TLS

Changes compared to the course

• Instead of using --go_opt=modules=github.com/Akos-T/grpc-go-course I'm using --go_opt=paths=source_relative. Same for --go-grpc_opt.
• Instead of using a makefile, I'm using Buf CLI and go generate.

Prerequisites

• Install Buf if you don't have it yet
  • If you use homebrew, run brew install bufbuild/buf/buf
  • If you don't use homebrew, please see here how to install Buf
• Install protoc for Go
  • go install google.golang.org/protobuf/cmd/protoc-gen-go@v1.28
  • go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@v1.2
  • Run export PATH="$PATH:$(go env GOPATH)/bin"
    • To make this permanent, you should add this to your terminal profile, e.g.: .zshrc and restrart the terminal or run source ~/.zshrc
  • Details can be found here
• Alternatively, the Buf config can be changed to use remote plugins in which case you don't have to install protoc locally. See the docs here.

How to build the apps (greet / calculator)

1. This is only needed for greet: In the ssl folder, run ssl.sh to generate your self-signed certificates for TLS in greet
2. Navigate to the project folder (greet or calculator)
3. Run go generate
4. Start the server:
   1. In case of greet: ./bin/greet/server
   2. In case of calculator: ./bin/server
5. Start the client:
   1. In case of greet: ./bin/greet/client
   2. In case of calculator: ./bin/client

How to build the blog app

1. Navigate to the blog folder
2. Run go generate
3. Run docker compose up
4. In another terminal navigate to the blog folder and run ./bin/server
5. In another terminal navigate to the blog folder and run ./bin/client

How to run the greet tests

1. Navigate to the greet folder
2. Run go test ./server

How to run Evans CLI/REPL or grpcURL with (m)TLS (Greet app)

1. Run the server (for steps, see the How to build the apps section above)
2. Install Evans CLI if haven't already: https://github.com/ktr0731/evans?tab=readme-ov-file#installation
3. Run evans --tls --host localhost -p 5051 --cacert "../ssl/ca.crt" -r repl
4. Use Evans REPL however you want to. E.g.:

   show package
   package <<package name>>
   show service
   service <<service name>>
   call <<RPC name>>
   

Documentation: https://github.com/ktr0731/evans?tab=readme-ov-file#usage-repl

Alternatively it is possible to use grpcURL, for example:

# With mTLS
grpcurl -cacert "../ssl/ca.crt" -d '{"first_name":"Maynard"}' localhost:5051 greet.GreetService.Greet

# With TLS, but we don't check the server's certificate (no mTLS)
grpcurl -insecure -d '{"first_name":"Maynard"}' localhost:5051 greet.GreetService.Greet

# Without TLS - If TLS is turned on in the server, this will timeout
grpcurl -plaintext -d '{"first_name":"Maynard"}' localhost:5051 greet.GreetService.Greet

Response in each case:

{
  "result": "Hello Maynard"
}

Certification - 2023-10-22

• Udemy: https://www.udemy.com/certificate/UC-f25db073-5270-4204-98df-5e2fe9913c55/
• LinkedIn Post: https://www.linkedin.com/feed/update/urn:li:activity:7121857412495532032/

Useful links

• https://www.udemy.com/course/grpc-golang/
• https://grpc.io/docs/languages/go/quickstart/
• https://buf.build/docs/installation
• https://github.com/Clement-Jean/grpc-go-course/blob/master/ssl/ssl.sh
• https://github.com/ktr0731/evans
• https://github.com/fullstorydev/grpcurl