SimpleReactiveElasticsearchRepository] Constructor threw exception

这个错误的原因可能有好几个，你可以做如下检查：如果你想找一个直接可用的例子话，你可以使用最近我搭建的这一个：emo-springboot-elasticsearch

1. ElasticSearch的版本比较新，需要SSL链接

在连接elastic search的时候，需要增加sslContext，

你需要先复制ES的证书出来，如果你的ES也是docker搭建的，可以直接通过下面的命令复制出来http_ca.crt 并且放入你的项目中

docker cp es01:/usr/share/elasticsearch/config/certs/http_ca.crt .

然后在代码中，加载这个ca.crt到sslContext中，关键代码就是.usingSsl(getSslContext(), (hostname, session) -> true) 这一行。

, (hostname, session) -> true 这个是可选参数，如果你的代码和ES在同一台电脑，那么不配置这个也可以，如果是不同电脑，那么需要这个参数申明不校验ES的证书。

package run.runnable.demospringbootelasticsearch.config;

import lombok.SneakyThrows;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.Environment;
import org.springframework.core.io.Resource;
import org.springframework.data.elasticsearch.client.ClientConfiguration;
import org.springframework.data.elasticsearch.client.elc.ReactiveElasticsearchConfiguration;

import javax.net.ssl.SSLContext;
import javax.net.ssl.TrustManagerFactory;
import java.io.IOException;
import java.security.KeyManagementException;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.cert.Certificate;
import java.security.cert.CertificateException;
import java.security.cert.CertificateFactory;
import java.time.Duration;

/**
 * @author Asher
 * on 2023/7/25
 */
@Configuration
public class ElasticSearchConfig extends ReactiveElasticsearchConfiguration {

    @Value("${spring.profiles.active}")
    public String env;

    @Value("${elastic.username}")
    public String esUsername;

    @Value("${elastic.password}")
    public String esPassword;

    @Value("${elastic.hostAndPort}")
    public String esHostAndPort;

    @Value("classpath:elastic-search/http_ca.crt")
    private Resource elasticCert;

    @Autowired
    private Environment environment;

    @SneakyThrows
    @Override
    public ClientConfiguration clientConfiguration() {
        return ClientConfiguration.builder()
                .connectedTo(esHostAndPort)
								//指定sslContext, 接受elastic search的证书
                .usingSsl(getSslContext(), (hostname, session) -> true)
                .withConnectTimeout(Duration.ofSeconds(5))
                .withSocketTimeout(Duration.ofSeconds(30))
                .withBasicAuth(esUsername, esPassword)
                .build();
    }

    /**
     * getSslContext
     * @return
     * @throws CertificateException
     * @throws IOException
     * @throws KeyStoreException
     * @throws NoSuchAlgorithmException
     * @throws KeyManagementException
     */
    private SSLContext getSslContext()
            throws CertificateException, IOException, KeyStoreException, NoSuchAlgorithmException, KeyManagementException {

        Certificate ca = CertificateFactory.getInstance("X.509")
                .generateCertificate(elasticCert.getInputStream());

        // Create a KeyStore containing our trusted CAs
        String keyStoreType = KeyStore.getDefaultType();
        KeyStore keyStore = KeyStore.getInstance(keyStoreType);
        keyStore.load(null, null);
        keyStore.setCertificateEntry("ca", ca);

        // Create a TrustManager that trusts the CAs in our KeyStore
        String tmfAlgorithm = TrustManagerFactory.getDefaultAlgorithm();
        TrustManagerFactory tmf = TrustManagerFactory.getInstance(tmfAlgorithm);
        tmf.init(keyStore);

        // Create an SSLContext that uses our TrustManager
        SSLContext context = SSLContext.getInstance("TLS");
        context.init(null, tmf.getTrustManagers(), null);
        return context;
    }
}