[FEATURE] https connection using Spring Boot SSL Bundle

[aivish]

Is your feature request related to a problem?

When connecting to OpenSearch via https it would be nice to configure in properties which SSL Bundle to use. There already seem to be some properties for this:

opensearch:
  uris: https://opensearch-host:9200
  restclient:
    ssl:
      bundle: example

spring:
  ssl:
    bundle:
      pem:
        example:
          truststore:
            certificate: file:/path/to/opensearch.ca

But unless I'm doing something wrong the bundle is not used, maybe those properties are just there because OpenSearchProperties uses Restclient properties from Elasticsearch.

For this configuration to work I had to create custom RestClientBuilderCustomizer with something like this:

@Override
public void customize(HttpAsyncClientBuilder builder) {
    String sslBundleName = properties.getRestclient().getSsl().getBundle();
    if (StringUtils.hasText(sslBundleName)) {
        SslBundle sslBundle = sslBundles.getBundle(sslBundleName);
        SSLContext sslcontext = sslBundle.createSslContext();
        SslOptions sslOptions = sslBundle.getOptions();

        builder.setSSLContext(sslcontext);
        builder.setSSLStrategy(new SSLIOSessionStrategy(sslcontext, sslOptions.getEnabledProtocols(), sslOptions.getCiphers(), (HostnameVerifier) null));
    }
}

Maybe this should be part of OpenSearchRestClientConfigurations, applied by the DefaultRestClientBuilderCustomizer or set as part of opensearchRestClientBuilder? Elasticsearch autoconfiguration is doing something similar here - https://github.com/spring-projects/spring-boot/blob/v3.4.0/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/elasticsearch/ElasticsearchRestClientConfigurations.java#L97.

What solution would you like?

Configure opensearch.restclient.ssl.bundle without needing to create any additional RestClientBuilderCustomizer's .

What alternatives have you considered?

Create RestClientBuilderCustomizer or add my OpenSearch CA to global trust store (probably would work, but didn't try, don't really want to do that).

Do you have any additional context?

If this makes sense and looks reasonable I can try creating PR for this.