What's
cloud-native?

There is no cloud.
It's just someone else's computers.

Cloud native Technologies
empower to build and run
scalable applications
in modern, dynamic environments.Cloud Native Computing Foundation

The 12-Factor-App and Beyond

Getting Started

Project Overview

Player vs. Computer API Calls

>_ Demo

Split into Session

• Go Session
• Spring Session

Go Session

Prerequisites Go Session

First Steps in Go

1. Get up and running
2. Complete REST API
3. Make Cloud Native or add your Features

Go Cloud Native Path

Cheatsheet Middleware for Logging and Recovery

                  r := chi.NewRouter()
                  r.Use(middleware.Logger)
                  r.Use(middleware.Recoverer)
                

• What does the recovery middleware do?
• Bonus: How can you set a request timeout using middleware?

Cheatsheet Configure Port
from Environment Variable

                  func main() {
                    http.ListenAndServe(fmt.Sprintf(":%v", os.Getenv("PORT")), r)
                  }
                

Using envconfig

                  // Application Configuration
                  type Config struct {
                    Port string `envconfig:"PORT" default:"8080"`
                  }
                  
                  func main() {
                    http.ListenAndServe(fmt.Sprintf(":%v", c.Port), r)
                  }     
                

Cheatsheet Handle Errors properly

Using the Standard Library

                  if err != nil {
                    http.Error(w, "Oops, that went wrong!", http.StatusInternalServerError)
                    return
                  }
                

Using Problem for HTTP APIs

                  if err != nil {
                    problem.New(
                    problem.Wrap(err), 
                    problem.Status(http.StatusInternalServerError)
                    ).WriteTo(w)
                    return
                  }        

Cheatsheet Run in Container

                    # 1. RPS Builder
                    FROM golang as builder
                    WORKDIR /app
                    ADD . /app
                    RUN CGO_ENABLED=0 go build -ldflags="-w -s" -o build/rps .
                    
                    # 2. RPS Container
                    FROM gcr.io/distroless/static
                    COPY --from=builder /app/build/rps /usr/bin/
                    EXPOSE 8080
                    ENTRYPOINT ["/usr/bin/rps"]
                  

Cheatsheet Add a Health Check

                    // Register Health Check
                    h, _ := health.New(health.WithChecks(
                    health.Config{
                      Name:      "db",
                      Timeout:   time.Second * 2,
                      SkipOnErr: false,
                      Check: healthPgx.New(healthPgx.Config{
                        DSN: config.Db,
                      }),
                    },
                    ))
                    
                    // Register Health Check Handler Function
                    r.Get("/health", h.HandlerFunc)
                  

Cheatsheet Use PostgreSQL for Storage

• SQL Tutorial with Go
• PostgreSQL Driver PGX
• Sample application offer

Cheatsheet Cloud Deployment

                    services:
                    - type: web
                    name: backend-go
                    env: go
                    plan: free
                    rootDir: backend-go
                    buildCommand: go build -o rps .
                    startCommand: ./rps
                  

Cheatsheet OpenTelemetry

Spring Session

Prerequisites Spring Session

First Steps Spring Session

1. Run local Frontend together with example backend
   https://backend-spring.onrender.com/api/v1
2. Build and Run Spring Backend
3. Implement REST API
4. Make Cloud Native or add further Features

Spring Cloud Native Path

Cheatsheet Error Handling

• Use JSON Problem Details (RFC 7807)
• Create a Http Error Handler

Cheatsheet Run in Container

• Spring Official Guide
• Baeldung: Dockerizing a Spring Boot Application