Introduction

This article describes how to build a sample service using Go micro in step by step fashion. Micro addresses the key requirements for building microservice systems. It takes the microservice architecture pattern and transforms it into a set of tools which act as the building blocks for scalable platforms

Installation

Install Go-Micro using the following commands

go get github.com/micro/go-micro

go get github.com/micro/micro

Initialization

A service is created like so using micro.NewService.

 

Go Micro also provides a way to set command line flags using micro.Flags

To parse flags use service.Init. Additionally access flags use the micro.Action option.

Go Micro provides predefined flags which are set and parsed if service.Init is called

Defining the API

We use protobuf files to define the service API interface. This is a very convenient way to st define the API and provide concrete types for both the server and a client.

Here’s an example definition.

Calculate.proto

Here we’re defining a service handler called Calculate handler with the method Multiply which takes the parameter CalculateRequest type and returns CalculateResponse.

To compile proto file

protoc –proto_path=$GOPATH/src:. –micro_out=. –go_out=. Calculate.proto

Generate the API interface

We use protoc, protoc-gen-go and protoc-gen-micro to generate the concrete go implementation for this definition.

go get github.com/golang/protobuf/{proto,protoc-gen-go}

go get github.com/micro/protoc-gen-micro

The types generated can now be imported and used within a handler for a server or the client when making a request.

Here’s part of the generated code.

Implement the handler

The server requires handlers to be registered to serve requests. A handler is an public type with public methods which conform to the signature func(ctx context.Context, req interface{}, rsp interface{}) error.

Here’s an implementation of the handler.

The complete service

main.go

You can run service using  go run main.go and run client using  go run main.go –run_client