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Upgrading your project from Go-Micro v2 to Micro v3

Introduction

As part of v3 we’ve simplified the development model and consolidated the micro and go-micro libraries. This means that you, as the developer, only need to worry about leveraging the libraries offered in micro. Users of the now deprecated go-micro framework can follow this guide to upgrade their projects to use Micro v3.

Service

In go-micro, you would create a service by importing github.com/micro/go-micro and using the following syntax:

  srv := micro.NewService(
    micro.Name("go.micro.service.foo")
  )

In Micro V3, we’ve removed namespaces from service names, so the above service would now be named simply foo. We’ve also created a package specifically for services: github.com/micro/micro/v3/service. Dotted service names can still be used, however the full service name will be required when calling the API, such as: “http://localhost:8080/go.micro.service.foo/Bar”, unless the API is configured with the namespace flag.

The above service can now be defined as:

  srv := service.New(
    service.Name("foo")
  )

Packages

In go-micro, modules such as config could only be accessed via the service object, for example srv.Options().Config.Read(). In Micro this has been made easier by providing public functions in each package which can be accessed by importing any package, nested within “github.com/micro/micro/v3/service”. Here is an example of how you can load config in Micro:

package main

import (
  "github.com/micro/micro/v3/service"
  "github.com/micro/micro/v3/service/config"
  "github.com/micro/micro/v3/service/logger"
)

func main() {
  // Create the service
  srv := service.New(
    service.Name("config-example"),
  )

  // Load the config
  val, err := config.Get("mykey")
  if err != nil {
    logger.Fatalf("Could not load mykey: %v", err)
  } else {
    logger.Infof("mykey = %v", val)
  }

  // Run the service
  if err := srv.Run(); err != nil {
    logger.Fatal(err)
  }
}

Other examples of packages which can be imported in this manner are:

• Auth
• Broker
• Client
• Config
• Context
• Errors
• Logger
• Store

Running services

Go Micro services interfaced directly with the underlying infrastructure, meaning they could be run using go run. In Micro V3 this has been abstracted using the micro server. The Micro server provides a level of abstraction to the underlying infrastructure, keeping your services unbound from their dependancies.

In practice, this means you need to be connected to a micro environment when running your services. You can spin up this environment locally using the micro server command, or connect to the free platform provided by M3O using micro env set platform. You can read more about running a service in our getting started guide.

Note: don’t forget to run your micro v3 services using micro run . instead of go run .