Introduction to the sample app

This series of quickstarts uses a sample app composed of two microservices to show how to deploy a .NET Core Steeltoe app to the Azure Spring Cloud service. You'll use Azure Spring Cloud capabilities such as service discovery, config server, logs, metrics, and distributed tracing.

Functional services

The sample app is composed of two microservices:

• The planet-weather-provider service returns weather text in response to an HTTP request that specifies the planet name. For example, it may return "very warm" for planet Mercury. It gets the weather data from the Config server. The Config server gets the weather data from a YAML file in a Git repository, for example:

  MercuryWeather: very warm
  VenusWeather: quite unpleasant
  MarsWeather: very cool
  SaturnWeather: a little bit sandy
  

• The solar-system-weather service returns data for four planets in response to an HTTP request. It gets the data by making four HTTP requests to planet-weather-provider. It uses the Eureka server discovery service to call planet-weather-provider. It returns JSON, for example:

  [{
       "Key": "Mercury",
       "Value": "very warm"
  }, {
       "Key": "Venus",
       "Value": "quite unpleasant"
  }, {
       "Key": "Mars",
       "Value": "very cool"
  }, {
       "Key": "Saturn",
       "Value": "a little bit sandy"
  }]
  

The following diagram illustrates the sample app architecture:

Code repository

The sample app is located in the steeltoe-sample folder of the Azure-Samples/Azure-Spring-Cloud-Samples repository on GitHub.

The instructions in the following quickstarts refer to the source code as needed.

In this quickstart, we use the microservices version of the well-known sample app PetClinic that will show you how to deploy apps to the Azure Spring Cloud service. The Pet Clinic sample demonstrates the microservice architecture pattern and highlights the services breakdown. You will see how services are deployed to Azure with Azure Spring Cloud capabilities, including service discovery, config server, logs, metrics, distributed tracing, and developer-friendly tooling support.

To follow the Azure Spring Cloud deployment examples, you only need the location of the source code, which is provided as needed.

Functional services to be deployed

PetClinic is decomposed into 4 core microservices. All of them are independently deployable applications organized by business domains.

• Customers service: Contains general user input logic and validation including pets and owners information (Name, Address, City, Telephone).
• Visits service: Stores and shows visits information for each pets' comments.
• Vets service: Stores and shows Veterinarians' information, including names and specialties.
• API Gateway: The API Gateway is a single entry point into the system, used to handle requests and route them to an appropriate service or to invoke multiple services, and aggregate the results. The three core services expose an external API to client. In real-world systems, the number of functions can grow very quickly with system complexity. Hundreds of services might be involved in rendering one complex webpage.

Infrastructure services hosted by Azure Spring Cloud

There are several common patterns in distributed systems that support core services. Azure Spring Cloud provides tools that enhance Spring Boot applications to implement the following patterns:

• Config service: Azure Spring Cloud Config is a horizontally scalable centralized configuration service for distributed systems. It uses a pluggable repository that currently supports local storage, Git, and Subversion.
• Service discovery: It allows automatic detection of network locations for service instances, which could have dynamically assigned addresses because of autoscaling, failures, and upgrades.

Database configuration

In its default configuration, Pet Clinic uses an in-memory database (HSQLDB) which is populated at startup with data. A similar setup is provided for MySql if a persistent database configuration is needed. A dependency for Connector/J, the MySQL JDBC driver, is already included in the pom.xml files.

Sample usage of PetClinic

For full implementation details, see our fork of PetClinic. The samples reference the source code as needed.