Allow https communication per ec2 or s3 service

By default all communication w/ AWS services done by this plugin is sent the clear over `http`, overriding amazons own default of https: http://docs.aws.amazon.com/AWSJavaSDK/latest/javadoc/com/amazonaws/ClientConfiguration.html#getProtocol()

One has to set `cloud.aws.protocol` in `elasticsearch.yml` to force SSL.

    cloud.aws.protocol: https

This is not entirely clear to the average user, and should be added to the documentation on both this project's README.

Closes #101.

README.md

@@ -42,6 +42,23 @@ cloud:
         secret_key: vExyMThREXeRMm/b/LRzEB8jWwvzQeXgjqMX+6br
 ```
 
+### Transport security
+
+By default this plugin uses HTTP for all API calls to AWS endpoints. If you wish to configure HTTPS you can set 
+`cloud.aws.protocol` in the elasticsearch config. You can optionally override this setting per individual service 
+via: `cloud.aws.ec2.protocol` or `cloud.aws.s3.protocol`. 
+
+```
+cloud:
+    aws:
+        protocol: http
+        s3: 
+            protocol: https
+        ec2: 
+            protocol: http
+
+```
+
 ### Region
 
 The `cloud.aws.region` can be set to a region and will automatically use the relevant settings for both `ec2` and `s3`. The available values are:

src/main/java/org/elasticsearch/cloud/aws/AwsEc2Service.java

@@ -61,6 +61,7 @@ public class AwsEc2Service extends AbstractLifecycleComponent<AwsEc2Service> {
 
         ClientConfiguration clientConfiguration = new ClientConfiguration();
         String protocol = componentSettings.get("protocol", "http").toLowerCase();
+        protocol = componentSettings.get("ec2.protocol", protocol).toLowerCase();
         if ("http".equals(protocol)) {
             clientConfiguration.setProtocol(Protocol.HTTP);
         } else if ("https".equals(protocol)) {

src/main/java/org/elasticsearch/cloud/aws/InternalAwsS3Service.java

@@ -89,6 +89,7 @@ public class InternalAwsS3Service extends AbstractLifecycleComponent<AwsS3Servic
 
         ClientConfiguration clientConfiguration = new ClientConfiguration();
         String protocol = componentSettings.get("protocol", "http").toLowerCase();
+        protocol = componentSettings.get("s3.protocol", protocol).toLowerCase();
         if ("http".equals(protocol)) {
             clientConfiguration.setProtocol(Protocol.HTTP);
         } else if ("https".equals(protocol)) {

src/test/java/org/elasticsearch/repositories/s3/S3SnapshotRestoreAbstractTest.java

@@ -55,7 +55,7 @@ import static org.hamcrest.Matchers.*;
  */
 @AwsTest
 @ClusterScope(scope = Scope.SUITE, numDataNodes = 2, numClientNodes = 0, transportClientRatio = 0.0)
-public class S3SnapshotRestoreTest extends AbstractAwsTest {
+abstract public class S3SnapshotRestoreAbstractTest extends AbstractAwsTest {
 
     @Override
     public Settings indexSettings() {

src/test/java/org/elasticsearch/repositories/s3/S3SnapshotRestoreOverHttpTest.java

@@ -0,0 +1,35 @@
+/*
+ * Licensed to Elasticsearch (the "Author") under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. Author licenses this
+ * file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.repositories.s3;
+
+import org.elasticsearch.common.settings.ImmutableSettings;
+import org.elasticsearch.common.settings.Settings;
+
+/**
+ */
+public class S3SnapshotRestoreOverHttpTest extends S3SnapshotRestoreAbstractTest {
+    @Override
+    public Settings nodeSettings(int nodeOrdinal) {
+        ImmutableSettings.Builder settings = ImmutableSettings.builder()
+                .put(super.nodeSettings(nodeOrdinal))
+                .put("cloud.aws.s3.protocol", "http");
+        return settings.build();
+    }
+}

src/test/java/org/elasticsearch/repositories/s3/S3SnapshotRestoreOverHttpsTest.java

@@ -0,0 +1,35 @@
+/*
+ * Licensed to Elasticsearch (the "Author") under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. Author licenses this
+ * file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.repositories.s3;
+
+import org.elasticsearch.common.settings.ImmutableSettings;
+import org.elasticsearch.common.settings.Settings;
+
+/**
+ */
+public class S3SnapshotRestoreOverHttpsTest extends S3SnapshotRestoreAbstractTest {
+    @Override
+    public Settings nodeSettings(int nodeOrdinal) {
+        ImmutableSettings.Builder settings = ImmutableSettings.builder()
+                .put(super.nodeSettings(nodeOrdinal))
+                .put("cloud.aws.s3.protocol", "https");
+        return settings.build();
+    }
+}