Consul distributed config and service discovery

• Update application configuration without restarting app/pod/instance
• Service discovery

Start consul server

docker build -t consul .
docker run -p 8080:8080 consul

• Access consul web ui http://localhost:8080/ui/
• Login using foo:bar

• Create a key/value

config/application/data

spring:
  datasource:
    driverClassName: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/asicdv?useSSL=false
    username: root
    password: rootchanged

We can use three way to load configuration from consul

• key/value
• yaml
• file - Git

Configure application

• Add additional jars to pom.xml

    <org.springframework.cloud>2.0.0.RELEASE</org.springframework.cloud>

    <dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-consul-config</artifactId>
			<version>${org.springframework.cloud}</version>
		</dependency>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-consul-discovery</artifactId>
			<version>${org.springframework.cloud}</version>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-actuator</artifactId>
		</dependency>

• create bootstrap.yml with following config

spring:
  datasource:
    driverClassName: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/asicdv?useSSL=false
    username: root
    password: root    
  jpa:
    properties:
      hibernate:
        dialect: org.hibernate.dialect.MySQL5InnoDBDialect
    hibernate:
      jpa.generate-ddl: true
      ddl-auto: update
server:
  port: 8081 

• User @RefreshScope annotation to update config on runtime

@SpringBootApplication
@RefreshScope
@EntityScan("com.boot.entity")
public class BootAppApplication {

	
	public static void main(String[] args) {
		SpringApplication.run(BootAppApplication.class, args);
	}

	
	@Bean
    @ConfigurationProperties("spring.datasource")
	@Primary
    public DataSourceProperties dataSourceProperties() {
        return new DataSourceProperties();
    }

    @Bean
    @ConfigurationProperties("spring.datasource")
    @Primary
    public HikariDataSource dataSource(DataSourceProperties properties) {
        return properties.initializeDataSourceBuilder().type(HikariDataSource.class)
                .build();
    }
}

• Start application http://localhost:8081/

• On updating properties on consul, changes will reflect in app without restart