[EIS] Validate EIS Gateway URL if set

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/services/elastic/ElasticInferenceServiceSettings.java

@@ -7,14 +7,65 @@
 
 package org.elasticsearch.xpack.inference.services.elastic;
 
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
 import org.elasticsearch.common.settings.Setting;
 import org.elasticsearch.common.settings.Settings;
 
+import java.net.URI;
+import java.net.URISyntaxException;
 import java.util.List;
+import java.util.Objects;
+import java.util.Set;
 
+/**
+ * Class encapsulating any global setting for the EIS integration.
+ */
 public class ElasticInferenceServiceSettings {
 
-    static final Setting<String> EIS_GATEWAY_URL = Setting.simpleString("xpack.inference.eis.gateway.url", Setting.Property.NodeScope);
+    public static final Setting<String> EIS_GATEWAY_URL = Setting.simpleString(
+        "xpack.inference.eis.gateway.url",
+        new EisGatewayURLValidator(),
+        Setting.Property.NodeScope
+    );
+
+    private static final Logger log = LogManager.getLogger(ElasticInferenceServiceSettings.class);
+
+    /**
+     * Class to validate the EIS Gateway url set via `xpack.inference.eis.gateway.url`.
+     */
+    public static class EisGatewayURLValidator implements Setting.Validator<String> {
+
+        private static final Set<String> VALID_EIS_GATEWAY_SCHEMES = Set.of("http", "https");
+
+        @Override
+        public void validate(String value) {
+            if (Objects.isNull(value) || value.isEmpty()) {
+                // No validation needed, if eis-gateway URL is not set
+                log.debug("eis-gateway url not set. Skipping validation");
+                return;
+            }
+
+            try {
+                var uri = new URI(value);
+                var scheme = uri.getScheme();
+
+                if (scheme == null || VALID_EIS_GATEWAY_SCHEMES.contains(scheme) == false) {
+                    throw new IllegalArgumentException(
+                        "["
+                            + scheme
+                            + "] is not a valid URI scheme for the setting ["
+                            + ElasticInferenceServiceSettings.EIS_GATEWAY_URL.getKey()
+                            + "]. Use one of ["
+                            + String.join(",", VALID_EIS_GATEWAY_SCHEMES)
+                            + "]"
+                    );
+                }
+            } catch (URISyntaxException e) {
+                throw new IllegalArgumentException("[" + e.getInput() + "] is not a valid URI", e);
+            }
+        }
+    }
 
     // Adjust this variable to be volatile, if the setting can be updated at some point in time
     private final String eisGatewayUrl;

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/services/elastic/ElasticInferenceServiceSparseEmbeddingsModel.java

@@ -108,6 +108,12 @@ private URI createUri() throws URISyntaxException {
             default -> throw new IllegalArgumentException("Unsupported model for EIS [" + modelId + "]");
         }
 
-        return new URI(elasticInferenceServiceComponents().eisGatewayUrl() + "/sparse-text-embedding/" + modelIdUriPath);
+        var uriString = elasticInferenceServiceComponents().eisGatewayUrl() + "/sparse-text-embedding/" + modelIdUriPath;
+
+        // We perform the same validation here as when reading the setting to make sure that our extended URI is still valid
+        // This method throws, if the URI is invalid
+        new ElasticInferenceServiceSettings.EisGatewayURLValidator().validate(uriString);
+
+        return new URI(uriString);
     }
 }

x-pack/plugin/inference/src/test/java/org/elasticsearch/xpack/inference/services/elastic/ElasticInferenceServiceSettingsTests.java

@@ -0,0 +1,64 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+package org.elasticsearch.xpack.inference.services.elastic;
+
+import org.elasticsearch.test.ESTestCase;
+
+public class ElasticInferenceServiceSettingsTests extends ESTestCase {
+
+    public void testEisGatewayURLValidator_Validate_ThrowError_OnMissingURIScheme() {
+        expectThrows(
+            IllegalArgumentException.class,
+            () -> new ElasticInferenceServiceSettings.EisGatewayURLValidator().validate("www.missing-scheme-gateway-url.com")
+        );
+    }
+
+    public void testEisGatewayURLValidator_Validate_ThrowError_OnWrongURIScheme() {
+        expectThrows(
+            IllegalArgumentException.class,
+            () -> new ElasticInferenceServiceSettings.EisGatewayURLValidator().validate("file://www.missing-scheme-gateway-url.com")
+        );
+    }
+
+    public void testEisGatewayURLValidator_Validate_DoesNotThrowError_ForHTTP() {
+        var scheme = "http";
+
+        try {
+            new ElasticInferenceServiceSettings.EisGatewayURLValidator().validate(scheme + "://www.valid-gateway-url.com");
+        } catch (Exception e) {
+            fail(e, "Should not throw exception for " + "[" + scheme + "]");
+        }
+    }
+
+    public void testEisGatewayURLValidator_Validate_DoesNotThrowError_ForHTTPS() {
+        var scheme = "https";
+
+        try {
+            new ElasticInferenceServiceSettings.EisGatewayURLValidator().validate(scheme + "://www.valid-gateway-url.com");
+        } catch (Exception e) {
+            fail(e, "Should not throw exception for " + "[" + scheme + "]");
+        }
+    }
+
+    public void testEisGatewayURLValidator_Validate_DoesNotThrowError_IfURLNull() {
+        try {
+            new ElasticInferenceServiceSettings.EisGatewayURLValidator().validate(null);
+        } catch (Exception e) {
+            fail(e, "Should not throw exception for, if eis-gateway URL is null");
+        }
+    }
+
+    public void testEisGatewayURLValidator_Validate_DoesNotThrowError_IfURLEmpty() {
+        try {
+            new ElasticInferenceServiceSettings.EisGatewayURLValidator().validate("");
+        } catch (Exception e) {
+            fail(e, "Should not throw exception for, if eis-gateway URL is empty");
+        }
+    }
+
+}

x-pack/plugin/inference/src/test/java/org/elasticsearch/xpack/inference/services/elastic/ElasticInferenceServiceSparseEmbeddingsModelTests.java

@@ -15,6 +15,34 @@
 
 public class ElasticInferenceServiceSparseEmbeddingsModelTests extends ESTestCase {
 
+    public void testCreateURI_ThrowError_OnMissingURIScheme() {
+        expectThrows(IllegalArgumentException.class, () -> createModel("www.missing-scheme-gateway-url.com"));
+    }
+
+    public void testCreateURI_ThrowError_OnWrongURIScheme() {
+        expectThrows(IllegalArgumentException.class, () -> createModel("file://www.missing-scheme-gateway-url.com"));
+    }
+
+    public void testCreateURI_DoesNotThrowError_ForHTTP() {
+        var scheme = "http";
+
+        try {
+            createModel(scheme + "://www.valid-gateway-url.com");
+        } catch (Exception e) {
+            fail(e, "Should not throw exception for " + "[" + scheme + "]");
+        }
+    }
+
+    public void testCreateURI_DoesNotThrowError_ForHTTPS() {
+        var scheme = "https";
+
+        try {
+            createModel(scheme + "://www.valid-gateway-url.com");
+        } catch (Exception e) {
+            fail(e, "Should not throw exception for " + "[" + scheme + "]");
+        }
+    }
+
     public static ElasticInferenceServiceSparseEmbeddingsModel createModel(String url) {
         return createModel(url, null);
     }

x-pack/plugin/inference/src/test/java/org/elasticsearch/xpack/inference/services/elastic/ElasticInferenceServiceTests.java

@@ -492,7 +492,7 @@ private ElasticInferenceService createServiceWithMockSender() {
         return new ElasticInferenceService(
             mock(HttpRequestSender.Factory.class),
             createWithEmptySettings(threadPool),
-            new ElasticInferenceServiceComponents(null)
+            new ElasticInferenceServiceComponents("http://valid-eis-gateway-url.com")
         );
     }
 }