Add new connection parameter tunnelHost to use with tunnel cunnection.

src/main/java/org/opensearch/jdbc/config/ConnectionConfig.java

@@ -46,6 +46,7 @@ public class ConnectionConfig {
     private String trustStoreType;
     private boolean trustSelfSigned;
     private boolean hostnameVerification;
+    private String tunnelHost;
 
     private ConnectionConfig(Builder builder) {
         this.url = builder.getUrl();
@@ -80,6 +81,7 @@ private ConnectionConfig(Builder builder) {
         this.trustSelfSigned = builder.getTrustSelfSignedConnectionProperty().getValue();
 
         this.hostnameVerification = builder.getHostnameVerificationConnectionProperty().getValue();
+        this.tunnelHost = builder.getTunnelHostConnectionProperty().getValue();
     }
 
     public static Builder builder() {
@@ -182,6 +184,10 @@ public boolean hostnameVerification() {
         return hostnameVerification;
     }
 
+    public String tunnelHost() {
+        return tunnelHost;
+    }
+
     @Override
     public String toString() {
         return "ConnectionConfig{" +
@@ -209,6 +215,7 @@ public String toString() {
                 ", trustStoreType='" + trustStoreType + '\'' +
                 ", trustSelfSigned='" + trustSelfSigned + '\'' +
                 ", hostnameVerification='" + hostnameVerification + '\'' +
+                ", tunnelHost='" + tunnelHost + '\'' +
                 '}';
     }
 
@@ -256,6 +263,9 @@ public static class Builder {
         private HostnameVerificationConnectionProperty hostnameVerificationConnectionProperty
                 = new HostnameVerificationConnectionProperty();
 
+        private TunnelHostConnectionProperty tunnelHostConnectionProperty
+                = new TunnelHostConnectionProperty();
+
         ConnectionProperty[] connectionProperties = new ConnectionProperty[]{
                 hostProperty,
                 portProperty,
@@ -278,7 +288,8 @@ public static class Builder {
                 trustStorePasswordConnectionProperty,
                 trustStoreTypeConnectionProperty,
                 trustSelfSignedConnectionProperty,
-                hostnameVerificationConnectionProperty
+                hostnameVerificationConnectionProperty,
+                tunnelHostConnectionProperty
         };
 
         private String url = null;
@@ -385,6 +396,10 @@ public HostnameVerificationConnectionProperty getHostnameVerificationConnectionP
             return hostnameVerificationConnectionProperty;
         }
 
+        public TunnelHostConnectionProperty getTunnelHostConnectionProperty() {
+            return tunnelHostConnectionProperty;
+        }
+
         public Builder setLogWriter(PrintWriter printWriter) {
             this.logWriter = printWriter;
             return this;
@@ -401,8 +416,12 @@ public Builder setUrl(String url) {
 
         public Builder setPropertyMap(Map<String, Object> map) {
             if (map != null) {
-                propertyMap = new HashMap<>();
-                propertyMap.putAll(map);
+                if (propertyMap == null) {
+                    propertyMap = new HashMap<>();
+                }
+                for (Map.Entry<String, Object> pair : map.entrySet()) {
+                    propertyMap.put(pair.getKey().toLowerCase(), pair.getValue());
+                }
             }
             return this;
         }
@@ -422,7 +441,9 @@ public Builder overrideProperties(Map<String, Object> map) {
                 if (overrideMap == null) {
                     overrideMap = new HashMap<>();
                 }
-                this.overrideMap.putAll(map);
+                for (Map.Entry<String, Object> pair : map.entrySet()) {
+                    overrideMap.put(pair.getKey().toLowerCase(), pair.getValue());
+                }
             }
             return this;
         }
@@ -435,7 +456,7 @@ public Builder setProperties(Properties properties) {
 
                 while (enumeration.hasMoreElements()) {
                     String key = (String) enumeration.nextElement();
-                    this.properties.setProperty(key, properties.getProperty(key));
+                    this.properties.setProperty(key.toLowerCase(), properties.getProperty(key));
                 }
             }
             return this;
@@ -544,6 +565,7 @@ private void validateConfig() throws ConnectionPropertyException {
          * @return effective value
          */
         private Object getPropertyValueToSet(String key) {
+            key = key.toLowerCase();
             if (overrideMap != null && overrideMap.containsKey(key)) {
                 return overrideMap.get(key);
             }

src/main/java/org/opensearch/jdbc/config/HostConnectionProperty.java

@@ -6,15 +6,23 @@
 
 package org.opensearch.jdbc.config;
 
+import java.net.URI;
+
 public class HostConnectionProperty extends StringConnectionProperty {
     public static final String KEY = "host";
 
     public HostConnectionProperty() {
         super(KEY);
     }
 
+    @Override
+    protected String parseValue(Object value) throws ConnectionPropertyException {
+        String host = super.parseValue(value);
+        // URI class extracts host from the string. It requires a prefix to be set to parse it properly.
+        return URI.create(host.startsWith("http") ? host : "https://" + host).getAuthority();
+    }
+
     public String getDefault() {
         return "localhost";
     }
-
 }

src/main/java/org/opensearch/jdbc/config/TunnelHostConnectionProperty.java

@@ -0,0 +1,19 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package org.opensearch.jdbc.config;
+
+public class TunnelHostConnectionProperty extends StringConnectionProperty {
+    public static final String KEY = "tunnelHost";
+
+    public TunnelHostConnectionProperty() {
+        super(KEY);
+    }
+
+    public String getDefault() {
+        return null;
+    }
+
+}

src/main/java/org/opensearch/jdbc/internal/util/UrlParser.java

@@ -84,18 +84,18 @@ public static Properties parseProperties(final String inputUrl) throws URISyntax
             String path = uri.getPath();
 
             if (host != null)
-                props.setProperty(HostConnectionProperty.KEY, host);
+                props.setProperty(HostConnectionProperty.KEY.toLowerCase(), host);
 
             if (port != -1)
-                props.setProperty(PortConnectionProperty.KEY, Integer.toString(port));
+                props.setProperty(PortConnectionProperty.KEY.toLowerCase(), Integer.toString(port));
 
             if (path != null && path.length() > 0)
-                props.setProperty(PathConnectionProperty.KEY, path);
+                props.setProperty(PathConnectionProperty.KEY.toLowerCase(), path);
 
             if ("https".equalsIgnoreCase(scheme)) {
-                props.setProperty(UseSSLConnectionProperty.KEY, "true");
+                props.setProperty(UseSSLConnectionProperty.KEY.toLowerCase(), "true");
             } else if ("http".equalsIgnoreCase(scheme)) {
-                props.setProperty(UseSSLConnectionProperty.KEY, "false");
+                props.setProperty(UseSSLConnectionProperty.KEY.toLowerCase(), "false");
             } else {
                 throw new URISyntaxException(inputUrl, "Invalid scheme:"+scheme+". Only http and https are supported.");
             }
@@ -114,7 +114,7 @@ public static Properties parseProperties(final String inputUrl) throws URISyntax
                                         + kv[0]
                                         + ". Expected key=value pairs");
                     } else {
-                        props.setProperty(kv[0], kv[1]);
+                        props.setProperty(kv[0].toLowerCase(), kv[1]);
                     }
                 }
             }

src/main/java/org/opensearch/jdbc/transport/http/ApacheHttpTransport.java

@@ -119,7 +119,8 @@ public ApacheHttpTransport(ConnectionConfig connectionConfig, Logger log, String
                     new AWSRequestSigningApacheInterceptor(
                             "es",
                             signer,
-                            provider));
+                            provider,
+                            connectionConfig.tunnelHost()));
         }
 
         // TODO - can apply settings retry & backoff

src/main/java/org/opensearch/jdbc/transport/http/auth/aws/AWSRequestSigningApacheInterceptor.java

@@ -7,6 +7,7 @@
 package org.opensearch.jdbc.transport.http.auth.aws;
 
 import com.amazonaws.DefaultRequest;
+import com.amazonaws.auth.AWSCredentials;
 import com.amazonaws.auth.AWSCredentialsProvider;
 import com.amazonaws.auth.Signer;
 import com.amazonaws.http.HttpMethodName;
@@ -53,6 +54,12 @@ public class AWSRequestSigningApacheInterceptor implements HttpRequestIntercepto
      */
     private final AWSCredentialsProvider awsCredentialsProvider;
 
+    /**
+     * Hostname of the OpenSearch cluster, required to make a valid AWS signature in case if
+     * proxy/tunnel/gateway used.
+     */
+    private final String host;
+
     /**
      *
      * @param service service that we're connecting to
@@ -61,10 +68,12 @@ public class AWSRequestSigningApacheInterceptor implements HttpRequestIntercepto
      */
     public AWSRequestSigningApacheInterceptor(final String service,
                                               final Signer signer,
-                                              final AWSCredentialsProvider awsCredentialsProvider) {
+                                              final AWSCredentialsProvider awsCredentialsProvider,
+                                              final String host) {
         this.service = service;
         this.signer = signer;
         this.awsCredentialsProvider = awsCredentialsProvider;
+        this.host = host;
     }
 
     /**
@@ -83,9 +92,14 @@ public void process(final HttpRequest request, final HttpContext context)
         // Copy Apache HttpRequest to AWS DefaultRequest
         DefaultRequest<?> signableRequest = new DefaultRequest<>(service);
 
-        HttpHost host = (HttpHost) context.getAttribute(HTTP_TARGET_HOST);
-        if (host != null) {
-            signableRequest.setEndpoint(URI.create(host.toURI()));
+        if (host != null && !host.equals("")) {
+            // override host if given by user (`tunnelHost` connection parameter)
+            signableRequest.setEndpoint(URI.create(host.startsWith("http") ? host : "https://" + host));
+        } else {
+            HttpHost host = (HttpHost) context.getAttribute(HTTP_TARGET_HOST);
+            if (host != null) {
+                signableRequest.setEndpoint(URI.create(host.toURI()));
+            }
         }
         final HttpMethodName httpMethod =
                 HttpMethodName.fromValue(request.getRequestLine().getMethod());
@@ -120,6 +134,7 @@ public void process(final HttpRequest request, final HttpContext context)
                 httpEntityEnclosingRequest.setEntity(basicHttpEntity);
             }
         }
+
     }
 
     /**

src/test/java/org/opensearch/jdbc/test/KeyValuePairs.java

@@ -36,7 +36,7 @@ public StringKvp(String key, String value) {
 
     public static Properties toProperties(final StringKvp... kvps) {
         Properties props = new Properties();
-        Arrays.stream(kvps).forEach(kvp -> props.setProperty(kvp.getKey(), kvp.getValue()));
+        Arrays.stream(kvps).forEach(kvp -> props.setProperty(kvp.getKey().toLowerCase(), kvp.getValue()));
         return props;
     }
 

src/test/java/org/opensearch/jdbc/transport/http/auth/aws/AWSRequestSigningApacheInterceptorTests.java

@@ -97,7 +97,7 @@ private static AWSRequestSigningApacheInterceptor createInterceptor() {
                 new AWSStaticCredentialsProvider(new AnonymousAWSCredentials());
         return new AWSRequestSigningApacheInterceptor("servicename",
                 new AddHeaderSigner("Signature", "wuzzle"),
-                anonymousCredentialsProvider);
+                anonymousCredentialsProvider, null);
 
     }
 }