Spring Boot 揭祕與實戰（九） 應用監控篇 - HTTP 健康監控

Health 信息是從 ApplicationContext 中全部的 HealthIndicator 的 Bean 中收集的， Spring Boot 內置了一些 HealthIndicator。

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內置 HealthIndicator 監控檢測

Name	Description
CassandraHealthIndicator	Checks that a Cassandra database is up.
DiskSpaceHealthIndicator	Checks for low disk space.
DataSourceHealthIndicator	Checks that a connection to DataSource can be obtained.
ElasticsearchHealthIndicator	Checks that an Elasticsearch cluster is up.
JmsHealthIndicator	Checks that a JMS broker is up.
MailHealthIndicator	Checks that a mail server is up.
MongoHealthIndicator	Checks that a Mongo database is up.
RabbitHealthIndicator	Checks that a Rabbit server is up.
RedisHealthIndicator	Checks that a Redis server is up.
SolrHealthIndicator	Checks that a Solr server is up.

咱們，來看下源代碼清單。

可見，Spring Boot 幫忙咱們集成了許多比較常見的健康監控，例如 MySQL、 MongoDB、 Redis、 ElasticSearch、 Solr、 RabbitMQ 等。

自定義 HealthIndicator 監控檢測

通常狀況下，Spring Boot 提供的健康監控沒法知足咱們複雜的業務場景，此時，咱們就須要定製本身的 HealthIndicator， 擴展本身的業務監控。

咱們，實現 HealthIndicator 接口建立一個簡單的檢測器類。它的做用很簡單，只是進行服務狀態監測。此時，經過重寫 health() 方法來實現健康檢查。

@Component
public class CusStatusHealthIndicator implements HealthIndicator {

    @Override
    public Health health() {
        int errorCode = check(); 
        if (errorCode != 0) {
            return Health.down()
                    .withDetail("status", errorCode)
                    .withDetail("message", "服務故障")
                    .build();
        }
        return Health.up().build();
    }

    private int check(){
        // 對監控對象的檢測操做 
        return HttpStatus.NOT_FOUND.value();
    }
}複製代碼

咱們，來看看打印結果。

{
  "status": "DOWN",
  "cusStatus": {
    "status": 404,
    "message": "服務故障"
  }
}複製代碼

此外，咱們還能夠經過繼承 AbstractHealthIndicator 類，建立一個檢測器類。

@Component
public class CusDiskSpaceHealthIndicator extends AbstractHealthIndicator {

    private final FileStore fileStore;
    private final long thresholdBytes;

    @Autowired
    public CusDiskSpaceHealthIndicator(
            @Value("${health.filestore.path:/}") String path,
            @Value("${health.filestore.threshold.bytes:10485760}") long thresholdBytes) 
                    throws IOException {
        fileStore = Files.getFileStore(Paths.get(path));
        this.thresholdBytes = thresholdBytes;
    }

    @Override
    protected void doHealthCheck(Health.Builder builder) throws Exception {
        long diskFreeInBytes = fileStore.getUnallocatedSpace();
        if (diskFreeInBytes >= thresholdBytes) {
            builder.up();
        } else {
            builder.down();
        }

        long totalSpaceInBytes = fileStore.getTotalSpace();
        builder.withDetail("disk.free", diskFreeInBytes);
        builder.withDetail("disk.total", totalSpaceInBytes);
    }
}複製代碼

AbstractHealthIndicator 實現 HealthIndicator 接口，並重寫了 health() 方法來實現健康檢查。所以，咱們只須要重寫 doHealthCheck 方法便可。

通常狀況下，咱們不會直接實現 HealthIndicator 接口，而是繼承 AbstractHealthIndicator 抽象類。由於，咱們只須要重寫 doHealthCheck 方法，並在這個方法中咱們關注於具體的健康檢測的業務邏輯服務。

咱們，來看看打印結果。

{
  "status": "UP",
  "cusDiskSpace": {
    "status": "UP",
    "disk.free": 79479193600,
    "disk.total": 104856547328
  }
}複製代碼

源代碼

相關示例完整代碼： springboot-action

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