Go Micro

Go Micro is a pluggable RPC based microservice library which provides the fundamental building blocks for writing distributed applications. It is part of the Micro toolchain. It supports Proto-RPC and JSON-RPC as the request/response protocol out of the box and defaults to Consul for discovery.

Every aspect of go-micro is pluggable.

An example server can be found in examples/server.

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Features

Feature	Package	Built-in Plugin	Description
Discovery	Registry	consul	A way of locating services to communicate with
Client	Client	rpc	Used to make RPC requests to a service
Codec	Codec	proto,json	Encoding/Decoding handler for requests
Balancer	Selector	random	Service node filter and pool
Server	Server	rpc	Listens and serves RPC requests
Pub/Sub	Broker	http	Publish and Subscribe to events
Transport	Transport	http	Communication mechanism between services

Go Plugins

By default go-micro only provides a single implementation of each interface. Plugins can be found at github.com/micro/go-plugins. Contributions welcome!

Prerequisites

Consul is the default discovery mechanism provided in go-micro. Discovery is however pluggable.

Install Consul

https://www.consul.io/intro/getting-started/install.html

Getting Started

Run Consul

$ consul agent -server -bootstrap-expect 1 -data-dir /tmp/consul

Run Service

$ go run examples/server/main.go --logtostderr
I1108 11:08:19.926071   11358 server.go:96] Starting server go.micro.srv.example id go.micro.srv.example-04de4cf0-8609-11e5-bf3a-68a86d0d36b6
I1108 11:08:19.926407   11358 rpc_server.go:233] Listening on [::]:54080
I1108 11:08:19.926500   11358 http_broker.go:80] Broker Listening on [::]:54081
I1108 11:08:19.926632   11358 rpc_server.go:158] Registering node: go.micro.srv.example-04de4cf0-8609-11e5-bf3a-68a86d0d36b6

Test Service

$ go run examples/client/main.go 
go.micro.srv.example-59b6e0ab-0300-11e5-b696-68a86d0d36b6: Hello John

Writing a service

Create request/response proto

go-micro/examples/server/proto/example/example.proto:

syntax = "proto3";

message Request {
        string name = 1;
}

message Response {
        string msg = 1;
}

Compile proto protoc -I$GOPATH/src --go_out=$GOPATH/src $GOPATH/src/github.com/micro/go-micro/examples/server/proto/example/example.proto

Create request handler

go-micro/examples/server/handler/example.go:

package handler

import (
	log "github.com/golang/glog"
	c "github.com/micro/go-micro/context"
	example "github.com/micro/go-micro/examples/server/proto/example"
	"github.com/micro/go-micro/server"

	"golang.org/x/net/context"
)

type Example struct{}

func (e *Example) Call(ctx context.Context, req *example.Request, rsp *example.Response) error {
	md, _ := c.GetMetadata(ctx)
	log.Infof("Received Example.Call request with metadata: %v", md)
	rsp.Msg = server.Options().Id + ": Hello " + req.Name
	return nil
}

Init server

go-micro/examples/server/main.go:

package main

import (
	log "github.com/golang/glog"
	"github.com/micro/go-micro/cmd"
	"github.com/micro/go-micro/examples/server/handler"
	"github.com/micro/go-micro/server"
)

func main() {
	// optionally setup command line usage
	cmd.Init()

	// Initialise Server
	server.Init(
		server.Name("go.micro.srv.example"),
	)

	// Register Handlers
	server.Handle(
		server.NewHandler(
			new(handler.Example),
		),
	)

	// Run server
	if err := server.Run(); err != nil {
		log.Fatal(err)
	}
}

Run service

$ go run examples/server/main.go --logtostderr
I1108 11:08:19.926071   11358 server.go:96] Starting server go.micro.srv.example id go.micro.srv.example-04de4cf0-8609-11e5-bf3a-68a86d0d36b6
I1108 11:08:19.926407   11358 rpc_server.go:233] Listening on [::]:54080
I1108 11:08:19.926500   11358 http_broker.go:80] Broker Listening on [::]:54081
I1108 11:08:19.926632   11358 rpc_server.go:158] Registering node: go.micro.srv.example-04de4cf0-8609-11e5-bf3a-68a86d0d36b6