Cross-Cluster Search & Replication

# Remote cluster bağlantısı
curl -X PUT "http://localhost:9200/_cluster/settings" -H "Content-Type: application/json" -d'
{
  "persistent": {
    "cluster.remote.eu_cluster.seeds": ["eu-node1:9300", "eu-node2:9300"],
    "cluster.remote.us_cluster.seeds": ["us-node1:9300"]
  }
}'

# Cross-cluster search
curl -X GET "http://localhost:9200/local_index,eu_cluster:products,us_cluster:products/_search" -H "Content-Type: application/json" -d'
{
  "query": { "match": { "name": "Nike" } }
}'

# Cross-cluster replication (CCR) - follower index
curl -X PUT "http://localhost:9200/products-replica/_ccr/follow" -H "Content-Type: application/json" -d'
{
  "remote_cluster": "eu_cluster",
  "leader_index": "products"
}'

public class CrossClusterService
{
    private readonly ElasticsearchClient _client;

    public CrossClusterService(ElasticsearchClient client) => _client = client;

    // Cross-cluster search: query multiple clusters
    public async Task<List<Product>> GlobalSearchAsync(string query)
    {
        var response = await _client.SearchAsync<Product>(s => s
            .Index("local_products,eu_cluster:products,us_cluster:products")
            .Query(q => q.MultiMatch(mm => mm
                .Query(query)
                .Fields(new[] { "name^3", "description" })
                .Type(TextQueryType.BestFields)
                .Fuzziness(new Fuzziness("AUTO"))))
            .Size(20));
        return response.Documents.ToList();
    }

    // Check remote cluster connectivity
    public async Task<Dictionary<string, bool>> CheckRemoteClustersAsync()
    {
        var response = await _client.Cluster.RemoteInfoAsync();
        var result = new Dictionary<string, bool>();
        if (response.IsValidResponse)
        {
            foreach (var (name, info) in response)
                result[name] = info.Connected;
        }
        return result;
    }
}