Go Microservices

Projects Structure

please also read https://github.com/golang-standards/project-layout

Following is the proposed project structure when Back End Engineer team wants to create Golang microservice / application

<root>
  ├── bin
  |   ├── <service_name_executable>
  |   └── ...
  |
  ├── cmd
  |   ├── <service_name>_main.go
  |   └── ...
  |
  ├── deploy
  |   └── <service_name>
  |       ├── deployment.yml
  |       ├── Dockerfile
  |       └── service.yml
  |
  ├── docs
  |
  ├── domain
  │   ├── entity
  │   │   └── <domain_name>.go
  │   ├── valueobject
  │   │   └── <enum_name>.go
  │   ├── repository
  │   │   └── <interface_repository_name>.go
  │   ├── usecase
  │   │   └── <interface_usecase_name>.go
  │   ├── service
  │   │   └── <interface_service_name>.go
  |
  ├── internal
  |   |
  │   ├── mocks
  │   │   ├── <usecase_implementation>Mock.go
  │   │   ├── <service_implementation>Mock.go
  │   │   └── <repo_implementation>Mock.go
  │   ├── config
  │   |   ├── consul-template.config
  │   |   └── <service_name>.ctmpl
  |   |
  │   ├── delivery
  │   │   └── http
  |   |       ├── <domain_name>_init.go
  |   |       ├── <domain_name>_init_test.go
  |   |       ├── <domain_name>_handler.go
  |   |       └── <domain_name>_handler_test.go
  |   |
  |   ├── repository
  |   |   └── <repo_implementation>.go
  |   |
  |   └── usecase
  |       ├── <usecase_name>.go
  |       └── <usecase_name>_test.go
  |
  ├── vendor
  ├── README.txt
  └── MAKEFILE

No	Folder Name	Purpose
1.	bin	Golang executable file per service name
2.	cmd	Golang main program per service name
3.	deploy	Configuration file for deployment per service name
4.	docs	Repository documentation file
5.	domain/*/<domain_name>.go	Golang file that holds definiton for data model, usecase interface, and repository interface for each domain
6a.	internal/config	Functions, configs used by microsevices
6b.	internal/delivery/http	As per port adapter pattern, this the port definition that interfacing with outside world
6c.	internal/repository/<repo_implmentation>.go	Encapsulated Implementation of Repository Interface
6d.	internal/usecase	Golang file that holds business logic implementation
6d.1	internal/mocks	Mock file
7.	vendor	Golang external package dependencies
8.	README.md	Manual handbook to use the service
9.	MAKEFILE	Script definition to build, test, and deploy the application

Prerequisites

1. golang (v1.16.4 or above)
2. postgreSQL database
3. MongoDB database
4. Protobuf Compiler | https://github.com/protocolbuffers/protobuf/releases/tag/v3.17.3 (v3.17.3 or above)
5. Buf | https://docs.buf.build/installation
6. Golang Migrate | https://github.com/golang-migrate/migrate/tree/master/cmd/migrate
7. Mockery | https://github.com/vektra/mockery (v2.10.6 or above)

Installation

1. copy environment -> cp env.example .env
2. sync go modules -> go mod tidy
3. download required modules -> go mod download
4. download GRPC ecosystem modules ->
   go get github.com/grpc-ecosystem/grpc-gateway/v2/protoc-gen-grpc-gateway
go get google.golang.org/protobuf/cmd/protoc-gen-go
go get google.golang.org/grpc/cmd/protoc-gen-go-grpc
5. install GRPC ecosystem modules ->
   go install github.com/grpc-ecosystem/grpc-gateway/v2/protoc-gen-grpc-gateway
go install google.golang.org/protobuf/cmd/protoc-gen-go
go install google.golang.org/grpc/cmd/protoc-gen-go-grpc

Services

Migration Database

1. download and install golang-migrate -> https://github.com/golang-migrate/migrate/tree/master/cmd/migrate
2. migrate up service (eg. service auth) ->
   migrate -source "file://services/auth/migrations/pgsql" -database "postgres://username:pwd@localhost:5432/your_db?sslmode=disable&search_path=auth" up
3. create new migration (if needed) (eg. service auth) ->
   migrate create -ext sql -dir services/auth/migrations/pgsql create_my_table

GRPC Api Gateway

1. run app -> go run services/api/main.go

Service Auth

1. run app -> go run services/auth/main.go
2. test -> go test ./.../auth

Mock

Prerequisites

1. Prerequisites -> https://github.com/vektra/mockery

Generate Mock

1. go to your service directory (eg. auth) ->
   cd services/auth
2. run generate command ->
   mockery --all --case=snake