README.md

Exercise 10 - Blue/Green deployment

The blue-green deployment pattern allows you to test latest application changes on production infrastructure, but without exposing the changes to consumers until your testing is complete. In this section, we'll perform a blue-green deployment with Azure CLI. Although we will go through the deployment steps manually, the Azure CLI commands we'll use can be automated in a CI/CD pipeline.

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We are going to deploy a new release of the "weather-service" microservice that was developed in exercise 7.

Task 1 : Modify the current application

1. Navigate to C:\Users\demouser\weather-service\src\main\java\com\example\demo and open the WeatherController class and modify its getWeatherForCity() method so it always returns sunny weather (this will be an easy-to-spot graphical view of our modifications in the code):

package com.example.demo;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;

@Controller
@RequestMapping(path="/weather")
public class WeatherController {

    private final WeatherRepository weatherRepository;

    public WeatherController(WeatherRepository weatherRepository) {
        this.weatherRepository = weatherRepository;
    }

    @GetMapping("/city")
    public @ResponseBody Weather getWeatherForCity(@RequestParam("name") String cityName) {
        return weatherRepository.findById(cityName).map(weather -> {
            weather.setDescription("It's always sunny on Azure Spring Apps");
            weather.setIcon("weather-sunny");
            return weather;
        }).get();
    }
}

Task 2 : Deploy the new application to a new "green" deployment

1. Navigate to Git Bash and build a new version of the application and deploy it to a new deployment called green:

cd weather-service
./mvnw clean package -DskipTests
az spring app deployment create --name green --app weather-service --runtime-version Java_17 -g spring-apps-workshop-DID -s azure-spring-apps-lab-DID --artifact-path target/demo-0.0.1-SNAPSHOT.jar
cd ..

Note: Replace the DID with value, you can also find it from Environment details page.

2. Once the application is deployed, if you go to https://spring-training.azureedge.net/ you will still have the same data, as the new version of the microservice is now in a staging area and not in production yet.

3. Navigate back to Azure Portal, From the resource group spring-apps-workshop- select the Azure Spring Apps instance named azure-spring-apps-lab-.

4. Click Apps in the Settings section of the navigation pane and select weather-service.

5. Click Deployments under Settings and you should now see green deployment in Staging state.

   

6. You can test the green deployment by invoking the same URL as in exercise 7, but replacing the deployment name default with green:

curl https://***.test.azuremicroservices.io/weather-service/green/weather/city?name=Paris%2C%20France

5. And you should see the result of the recent modification:

   {"city":"Paris, France","description":"It's always sunny on Azure Spring Cloud","icon":"weather-sunny"}

   Note: We're not testing the green deployment through the gateway application. The purpose of a green deployment is to test changes to a microservice before routing production traffic to it. Therefore, if you access weather-service through the public Gateway URL, as you did in exercise 8, you will be routed to the original version of the service.

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