Go Lang Guide
Published in
6 min readJan 1, 2022
Summary
- Concepts of Go Lang
- Concepts of MicroService
- Application Payment Gateway
- Let’s Code in Go
- References
1. Concepts of Go Lang
Build fast, reliable, and efficient software at scale
- Go is an open-source programming language supported by Google
- Easy to learn and get started with
- Built-in concurrency and a robust standard library
- A growing ecosystem of partners, communities, and tools
How to Download
Docker Official Go Lang
docker pull golang
Start a Go instance in your app
The most straightforward way to use this image is to use a Go container as both the build and runtime environment. In your Dockerfile, writing something along the lines of the following will compile and run your project:
FROM golang:1.17WORKDIR /go/src/app
COPY . .RUN go get -d -v ./...
RUN go install -v ./...CMD ["app"]
You can then build and run the Docker image:
$ docker build -t my-golang-app .
$ docker run -it --rm --name my-running-app my-golang-app2. Concepts of MicroServices
Monolith vs Microservices Architecture
What are microservices?
- Microservices are small, independent, and loosely coupled. A single small team of developers can write and maintain a service.
- Each service is a separate codebase, which can be managed by a small development team.
- Services can be deployed independently. A team can update an existing service without rebuilding and redeploying the entire application.
- Services are responsible for persisting their own data or external state. This differs from the traditional model, where a separate data layer handles data persistence.
- Services communicate with each other by using well-defined APIs. Internal implementation details of each service are hidden from other services.
- Supports polyglot programming. For example, services don’t need to share the same technology stack, libraries, or frameworks.
Microservices Styles?
4. Application Payment Gateway
Components of Application
Components Payment Gateway
- NextJS = Frontend based Java Script
- Nest.JS = Backend, Update DataBase
- Apache Kafka = Massage Process
- Go Lang = MicroService Processing Payment
- Prometheus = Metrics
- Grafana = Dashboard
- Docker = Container
- Kubernetes = Orchestration, Deploy, Production
Domain Driven Design (DDD)
Transaction Processing in GoLang
Application Domain Rules
- A Transaction will have only two states: Approved or Reject
- The Minimum Amount for each transaction is $1.00
- The Maximum Amount for a Transaction to be approved is $1000
- Any Transaction between the amounts of $1 and $1,000 will always be approved
- For a transaction to be approved, the credit card details must be valid.
Use Case: “Process Transaction”
- You will receive the data of a transaction
- Will Create a Transaction
- Will add credit card to this transaction:
1) If the Credit Card is Invalid:
- The transaction data will be inserted into the database with status=rejected containing the error message
- The Transaction will be published on Apache Kafka
2) If the Transaction is NOT Approved:
- The transaction data will be inserted into the database with status=rejected containing the error message
- The Transaction will be published on Apache Kafka
3) If the Transaction is Approved:
- The transaction data will be inserted into the database with status=approved
- The Transaction will be published on Apache Kafka
DDD Adapters
Payment Gateway Adapters
1. Apache Kafka
- Message Consumption
- Message Production
2. Database
- Database Connection
- Inserting the Transaction into the Database
- SQLite / MySQL
- Repository Pattern
3. Presenter
- Will set the default of the message to be sent via Apache Kafka
- Apache Kafka Message Format
Clean Architecture Fundamentals
How would you think your software if…
- Major Changes in Business Rules
- Database Change
- Support Multiples Protocolos: REST, gRPC, Kafka, RabbitMQ, GraphQL
- CLI
Clean Architecture Elements
- Entities → Business Rules
- Use Cases
- Controllers
- Presenters
- Gateways
- DB
- UI
- External Interfaces
4. Let’s Code in Go
Github Repository
- Go Lang Installtion
curl -OL https://golang.org/dl/go1.17.5.linux-amd64.tar.gz
sha256sum go1.17.5.linux-amd64.tar.gz
bd78114b0d441b029c8fe0341f4910370925a4d270a6a590668840675b0c653e go1.17.5.linux-amd64.tar.gz
sudo tar -C /usr/local -xvf go1.17.5.linux-amd64.tar.gz
- sudo nano ~/.profile
- source ~/.profile
- go version
- go version go1.17.5 linux/amd64
Testing Go
- mkdir hello-go
- go mod init your_domain/hello
- hello.go
package main
import “fmt”
func main() {
fmt.Println(“Hello, World!”)
}
go run .
Go Lang with Docker Container
- docker exec -it aluno_app_1 bash
