Greengrass china endpoint (#162)

* Temporary fix for connection with greengrass china endpoint

* replace '-' with '.'

* Compile errors, refactor

* add override to allow unique endpoint to be used

* add javadoc comments and remove region parameter

Co-authored-by: Bret Ambrose <[email protected]>

Author: jmklix

sdk/src/main/java/software/amazon/awssdk/iot/discovery/DiscoveryClient.java

@@ -106,8 +106,13 @@ public void onResponseComplete(HttpStream httpStream, int errorCode) {
     }
 
     private static String getHostname(final DiscoveryClientConfig config) {
-        return String.format("greengrass-ats.iot.%s.%s",
-            config.getRegion(), AWS_DOMAIN_SUFFIX_MAP.getOrDefault(config.getRegion(), AWS_DOMAIN_DEFAULT));
+        //allow greengrass server endpoint to be manualy set for unique endpoints
+        if (config.getGGServerName().equals("")) {
+            return String.format("greengrass-ats.iot.%s.%s",
+                config.getRegion(), AWS_DOMAIN_SUFFIX_MAP.getOrDefault(config.getRegion(), AWS_DOMAIN_DEFAULT));
+        } else {
+            return String.format(config.getGGServerName());
+        }
     }
 
     @Override

sdk/src/main/java/software/amazon/awssdk/iot/discovery/DiscoveryClientConfig.java

@@ -16,8 +16,10 @@ public class DiscoveryClientConfig implements AutoCloseable {
     final private String region;
     final private int maxConnections;
     final private HttpProxyOptions proxyOptions;
+    final private String ggServerName;
 
     /**
+     * Constructor for DiscoveryClientConfig creates the correct endpoint if not in a special region
      *
      * @param bootstrap client bootstrap to use to establish network connections
      * @param tlsContextOptions tls configuration for client network connections.  For greengrass discovery, the
@@ -41,6 +43,35 @@ public DiscoveryClientConfig(
         this.region = region;
         this.maxConnections = maxConnections;
         this.proxyOptions = proxyOptions;
+        this.ggServerName = "";
+    }
+
+    /**
+     * Default Constructor for DiscoveryClientConfig that allows the specification of a specific ggServerName to use in special regions
+     * 
+     * @param bootstrap client bootstrap to use to establish network connections
+     * @param tlsContextOptions tls configuration for client network connections.  For greengrass discovery, the
+     *                          tls context must be initialized with the certificate and private key of the
+     *                          device/thing that is querying greengrass core availability.
+     * @param socketOptions socket configuration for client network connections
+     * @param maxConnections maximum concurrent http connections within the client
+     * @param proxyOptions proxy configuration for client network connections
+     * @param ggServerName full endpoint to use when connecting in special regions
+     */
+    public DiscoveryClientConfig(
+            final ClientBootstrap bootstrap,
+            final TlsContextOptions tlsContextOptions,
+            final SocketOptions socketOptions,
+            final int maxConnections,
+            final HttpProxyOptions proxyOptions,
+            final String ggServerName) {
+        this.bootstrap = bootstrap;
+        this.tlsContext = new TlsContext(tlsContextOptions);
+        this.socketOptions = socketOptions;
+        this.region = "";
+        this.maxConnections = maxConnections;
+        this.proxyOptions = proxyOptions;
+        this.ggServerName = ggServerName;
     }
 
     /**
@@ -85,6 +116,10 @@ public HttpProxyOptions getProxyOptions() {
         return proxyOptions;
     }
 
+    public String getGGServerName() {
+        return ggServerName;
+    }
+
     @Override
     public void close() {
         if(tlsContext != null) {