Initial support for OpenSearch Serverless, based simply on parsing URL

src/sqlodbc/opensearch_communication.cpp

@@ -16,12 +16,18 @@
 #include <aws/core/http/HttpClient.h>
 // clang-format on
 
-#define SQL_ENDPOINT_ERROR_STR "Error"
+static const std::string SQL_ENDPOINT_OPENSEARCH = "/_plugins/_sql";
+static const std::string SQL_ENDPOINT_ELASTICSEARCH = "/_opendistro/_sql";
+static const std::string SQL_ENDPOINT_ERROR = "Error";
+
+static const std::string SERVICE_NAME_DEFAULT = "es";
+static const std::string SERVICE_NAME_SERVERLESS = "aoss";
+
+static const std::string CREDENTIALS_PROFILE = "opensearchodbc";
+static const std::string CREDENTIALS_PROVIDER_ALLOCATION_TAG =
+    "CREDENTIAL_PROVIDER";
 
 static const std::string ctype = "application/json";
-static const std::string ALLOCATION_TAG = "AWS_SIGV4_AUTH";
-static const std::string SERVICE_NAME = "es";
-static const std::string ESODBC_PROFILE_NAME = "opensearchodbc";
 static const std::string ERROR_MSG_PREFIX =
     "[OpenSearch][SQL ODBC Driver][SQL Plugin] ";
 static const std::string JSON_SCHEMA =
@@ -433,7 +439,9 @@ OpenSearchCommunication::IssueRequest(
     }
 
     // Handle authentication
-    if (m_rt_opts.auth.auth_type == AUTHTYPE_BASIC) {
+    std::string& auth_type = m_rt_opts.auth.auth_type;
+
+    if (auth_type == AUTHTYPE_BASIC) {
         std::string userpw_str =
             m_rt_opts.auth.username + ":" + m_rt_opts.auth.password;
         Aws::Utils::Array< unsigned char > userpw_arr(
@@ -442,14 +450,23 @@ OpenSearchCommunication::IssueRequest(
         Aws::String hashed_userpw =
             Aws::Utils::HashingUtils::Base64Encode(userpw_arr);
         request->SetAuthorization("Basic " + hashed_userpw);
-    } else if (m_rt_opts.auth.auth_type == AUTHTYPE_IAM) {
+    }
+
+    // TODO #70: Handle serverless
+    else if (auth_type == AUTHTYPE_IAM) {
         std::shared_ptr< Aws::Auth::ProfileConfigFileAWSCredentialsProvider >
             credential_provider = Aws::MakeShared<
                 Aws::Auth::ProfileConfigFileAWSCredentialsProvider >(
-                ALLOCATION_TAG.c_str(), ESODBC_PROFILE_NAME.c_str());
+                CREDENTIALS_PROVIDER_ALLOCATION_TAG.c_str(),
+                CREDENTIALS_PROFILE.c_str());
+
+        const std::string& service_name =
+            isServerless()
+            ? SERVICE_NAME_SERVERLESS
+            : SERVICE_NAME_DEFAULT;
 
         Aws::Client::AWSAuthV4Signer signer(credential_provider,
-                                            SERVICE_NAME.c_str(),
+                                            service_name.c_str(),
                                             m_rt_opts.auth.region.c_str());
 
         if (m_rt_opts.auth.tunnel_host.length() > 0) {
@@ -548,26 +565,33 @@ bool OpenSearchCommunication::CheckSQLPluginAvailability() {
 }
 
 bool OpenSearchCommunication::EstablishConnection() {
-    // Generate HttpClient Connection class if it does not exist
+
     LogMsg(OPENSEARCH_ALL, "Attempting to establish DB connection.");
+
+    // Generate HttpClient Connection class if it does not exist
     if (!m_http_client) {
         InitializeConnection();
     }
 
-    // check if the endpoint is initialized
+    // Check if the endpoint can be determined.
     if (sql_endpoint.empty()) {
         SetSqlEndpoint();
     }
 
+    if (sql_endpoint == SQL_ENDPOINT_ERROR) {
+        LogMsg(OPENSEARCH_ERROR, m_error_message.c_str());
+        return false;
+    }
+
     // Check whether SQL plugin has been installed and enabled in the
     // OpenSearch server since the SQL plugin is a prerequisite to
     // use this driver.
-    if((sql_endpoint != SQL_ENDPOINT_ERROR_STR) && CheckSQLPluginAvailability()) {
-        return true;
+    if(!CheckSQLPluginAvailability()) {
+        LogMsg(OPENSEARCH_ERROR, m_error_message.c_str());
+        return false;
     }
 
-    LogMsg(OPENSEARCH_ERROR, m_error_message.c_str());
-    return false;
+    return true;
 }
 
 std::vector< std::string > OpenSearchCommunication::GetColumnsWithSelectQuery(
@@ -1048,15 +1072,39 @@ std::string OpenSearchCommunication::GetClusterName() {
 /**
  * @brief Sets URL endpoint for SQL plugin. On failure to
  * determine appropriate endpoint, value is set to SQL_ENDPOINT_ERROR_STR
- * 
+ *
  */
 void OpenSearchCommunication::SetSqlEndpoint() {
+
+    // TODO #70: Support serverless
+    if (isServerless()) {
+        sql_endpoint = SQL_ENDPOINT_OPENSEARCH;
+        return;
+    }
+
     std::string distribution = GetServerDistribution();
     if (distribution.empty()) {
-        sql_endpoint = SQL_ENDPOINT_ERROR_STR;
-    } else if (distribution.compare("opensearch") == 0) {
-        sql_endpoint = "/_plugins/_sql";
+        sql_endpoint = SQL_ENDPOINT_ERROR;
+    } else if (distribution == "opensearch") {
+        sql_endpoint = SQL_ENDPOINT_OPENSEARCH;
     } else {
-        sql_endpoint = "/_opendistro/_sql";
+        sql_endpoint = SQL_ENDPOINT_ELASTICSEARCH;
     }
 }
+
+/**
+ * Returns whether this is connecting to an OpenSearch Serverless cluster.
+ * @see
+ * https://docs.aws.amazon.com/opensearch-service/latest/developerguide/serverless-overview.html
+ */
+bool OpenSearchCommunication::isServerless() {
+
+    // TODO #70: Support serverless
+
+    // Parse the server URL.
+    if(m_rt_opts.conn.server.find("aoss.amazonaws.com") != std::string::npos) {
+        return true;
+    }
+
+    return false;
+}

src/sqlodbc/opensearch_communication.h

@@ -97,6 +97,9 @@ class OpenSearchCommunication {
     std::string m_response_str;
     std::shared_ptr< Aws::Http::HttpClient > m_http_client;
     std::string m_error_message_to_user;
+
+    // TODO #70 - Support serverless
+    bool isServerless();
 };
 
 #endif