Automatically add scheme to discovery.ec2.endpoint

CHANGELOG.md

@@ -172,6 +172,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Improve boolean parsing performance ([#11308](https://github.com/opensearch-project/OpenSearch/pull/11308))
 - Interpret byte array as primitive using VarHandles ([#11362](https://github.com/opensearch-project/OpenSearch/pull/11362))
 - Change error message when per shard document limit is breached ([#11312](https://github.com/opensearch-project/OpenSearch/pull/11312))
+- Automatically add scheme to discovery.ec2.endpoint ([#11512](https://github.com/opensearch-project/OpenSearch/pull/11512))
 - Restore support for Java 8 for RestClient ([#11562](https://github.com/opensearch-project/OpenSearch/pull/11562))
 
 ### Deprecated

plugins/discovery-ec2/src/main/java/org/opensearch/discovery/ec2/AwsEc2ServiceImpl.java

@@ -99,7 +99,7 @@ protected Ec2Client buildClient(
 
         if (Strings.hasText(endpoint)) {
             logger.debug("using explicit ec2 endpoint [{}]", endpoint);
-            builder.endpointOverride(URI.create(endpoint));
+            builder.endpointOverride(URI.create(getFullEndpoint(endpoint)));
         }
 
         if (Strings.hasText(region)) {
@@ -110,6 +110,19 @@ protected Ec2Client buildClient(
         return SocketAccess.doPrivileged(builder::build);
     }
 
+    protected String getFullEndpoint(String endpoint) {
+        if (!Strings.hasText(endpoint)) {
+            return null;
+        }
+        if (endpoint.startsWith("http")) {
+            return endpoint;
+        }
+
+        // if no scheme is provided, default to https
+        logger.debug("no scheme found in endpoint [{}], defaulting to https", endpoint);
+        return "https://" + endpoint;
+    }
+
     static ProxyConfiguration buildProxyConfiguration(Logger logger, Ec2ClientSettings clientSettings) {
         if (Strings.hasText(clientSettings.proxyHost)) {
             try {

plugins/discovery-ec2/src/test/java/org/opensearch/discovery/ec2/AwsEc2ServiceImplTests.java

@@ -202,4 +202,26 @@ public void testAWSConfigurationWithAwsSettings() {
         assertTrue(clientOverrideConfiguration.retryPolicy().isPresent());
         assertThat(clientOverrideConfiguration.retryPolicy().get().numRetries(), is(10));
     }
+
+    public void testGetFullEndpointWithScheme() {
+        final Settings settings = Settings.builder().put("discovery.ec2.endpoint", "http://ec2.us-west-2.amazonaws.com").build();
+        Ec2ClientSettings clientSettings = Ec2ClientSettings.getClientSettings(settings);
+
+        AwsEc2ServiceImpl awsEc2ServiceImpl = new AwsEc2ServiceImpl();
+
+        String endpoint = awsEc2ServiceImpl.getFullEndpoint(clientSettings.endpoint);
+        assertEquals("http://ec2.us-west-2.amazonaws.com", endpoint);
+    }
+
+    public void testGetFullEndpointWithoutScheme() {
+        final Settings settings = Settings.builder().put("discovery.ec2.endpoint", "ec2.us-west-2.amazonaws.com").build();
+        Ec2ClientSettings clientSettings = Ec2ClientSettings.getClientSettings(settings);
+
+        AwsEc2ServiceImpl awsEc2ServiceImpl = new AwsEc2ServiceImpl();
+
+        String endpoint = awsEc2ServiceImpl.getFullEndpoint(clientSettings.endpoint);
+        assertEquals("https://ec2.us-west-2.amazonaws.com", endpoint);
+
+        assertNull(awsEc2ServiceImpl.getFullEndpoint(""));
+    }
 }