SpringBoot组件Actuator数据源判活源码

背景说明

在生产环境中，需要实时或定期监控服务的可用性。Spring Boot的actuator（健康监控）功能提供了很多监控所需的接口，可以对应用系统进行配置查看、相关功能统计等。

这里针对Actuator组件对数据源[DataSource]判活进行源码阅读简要过程进行记录。

解决方案

组件引入

    org.springframework.boot
    spring-boot-starter-actuator

主类入口

1.X请阅读org.springframework.boot.actuate.health.DataSourceHealthIndicator
2.X 请阅读org.springframework.boot.actuate.jdbc.DataSourceHealthIndicator

核心流程

由于1.X和2.X在核心逻辑上并没有变化，只是对包名做了调整，这里针对2.X进行阅读分析,当我们需要对我们新建的一个模块进行健康监控的话，可以把这些监控信息统一归纳到health节点下，只需要实现HealthIndicator接口即可,当我们调用health端口获取监控状态时health方法会自动执行。

@FunctionalInterface
public interface HealthIndicator {

   /**
    * Return an indication of health.
    * @return the health for
    */
   Health health();

}

HealthIndicator-健康检查指示器

查看源码AbstractHealthIndicator的核心实现

public abstract class AbstractHealthIndicator implements HealthIndicator {
    @Override
    public final Health health() {
        Health.Builder builder = new Health.Builder();
        try {
            doHealthCheck(builder);
        }
        catch (Exception ex) {
            if (this.logger.isWarnEnabled()) {
                String message = this.healthCheckFailedMessage.apply(ex);
                this.logger.warn(StringUtils.hasText(message) ? message : DEFAULT_MESSAGE,
                        ex);
            }
            builder.down(ex);
        }
        return builder.build();
    }
    protected abstract void doHealthCheck(Health.Builder builder) throws Exception;
}

查看DataSourceHealthIndicator的核心实现

public class DataSourceHealthIndicator extends AbstractHealthIndicator implements InitializingBean {
    
    private static final String DEFAULT_QUERY = "SELECT 1";
    
    @Override
    protected void doHealthCheck(Health.Builder builder) throws Exception {
        if (this.dataSource == null) {
            builder.up().withDetail("database", "unknown");
        }
        else {
            doDataSourceHealthCheck(builder);
        }
    }
    private void doDataSourceHealthCheck(Health.Builder builder) throws Exception {
        String product = getProduct();
        builder.up().withDetail("database", product);
        String validationQuery = getValidationQuery(product);
        if (StringUtils.hasText(validationQuery)) {
            // Avoid calling getObject as it breaks MySQL on Java 7
            List