Allow Undertow's options to be configured via the environment

See gh-17356

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/ServerProperties.java

@@ -24,6 +24,7 @@ import java.time.Duration;
 import java.time.temporal.ChronoUnit;
 import java.util.ArrayList;
 import java.util.HashMap;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 
@@ -1119,6 +1120,8 @@ public class ServerProperties {
 
 		private final Accesslog accesslog = new Accesslog();
 
+		private final Options options = new Options();
+
 		public DataSize getMaxHttpPostSize() {
 			return this.maxHttpPostSize;
 		}
@@ -1227,6 +1230,10 @@ public class ServerProperties {
 			return this.accesslog;
 		}
 
+		public Options getOptions() {
+			return this.options;
+		}
+
 		/**
 		 * Undertow access log properties.
 		 */
@@ -1312,6 +1319,22 @@ public class ServerProperties {
 
 		}
 
+		public static class Options {
+
+			private Map<String, String> socket = new LinkedHashMap<>();
+
+			private Map<String, String> server = new LinkedHashMap<>();
+
+			public Map<String, String> getServer() {
+				return this.server;
+			}
+
+			public Map<String, String> getSocket() {
+				return this.socket;
+			}
+
+		}
+
 	}
 
 	/**

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/embedded/UndertowWebServerFactoryCustomizer.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.autoconfigure.web.embedded;
 
+import java.lang.reflect.Field;
+
 import io.undertow.UndertowOptions;
 import org.xnio.Option;
 
@@ -61,6 +63,7 @@ public class UndertowWebServerFactoryCustomizer
 	public void customize(ConfigurableUndertowWebServerFactory factory) {
 		ServerProperties properties = this.serverProperties;
 		ServerProperties.Undertow undertowProperties = properties.getUndertow();
+		ServerProperties.Undertow.Options undertowOptions = undertowProperties.getOptions();
 		ServerProperties.Undertow.Accesslog accesslogProperties = undertowProperties.getAccesslog();
 		PropertyMapper propertyMapper = PropertyMapper.get().alwaysApplyingWhenNonNull();
 		propertyMapper.from(undertowProperties::getBufferSize).whenNonNull().asInt(DataSize::toBytes)
@@ -109,6 +112,12 @@ public class UndertowWebServerFactoryCustomizer
 				.to((alwaysSetKeepAlive) -> customizeServerOption(factory, UndertowOptions.ALWAYS_SET_KEEP_ALIVE,
 						alwaysSetKeepAlive));
 
+		propertyMapper.from(undertowOptions::getServer)
+				.to((server) -> server.forEach((key, value) -> setCustomOption(factory, key, value, "server")));
+
+		propertyMapper.from(undertowOptions::getSocket)
+				.to((socket) -> socket.forEach((key, value) -> setCustomOption(factory, key, value, "socket")));
+
 		factory.addDeploymentInfoCustomizers(
 				(deploymentInfo) -> deploymentInfo.setEagerFilterInit(undertowProperties.isEagerFilterInit()));
 	}
@@ -121,6 +130,10 @@ public class UndertowWebServerFactoryCustomizer
 		factory.addBuilderCustomizers((builder) -> builder.setServerOption(option, value));
 	}
 
+	private <T> void customizeSocketOption(ConfigurableUndertowWebServerFactory factory, Option<T> option, T value) {
+		factory.addBuilderCustomizers((builder) -> builder.setSocketOption(option, value));
+	}
+
 	private boolean getOrDeduceUseForwardHeaders() {
 		if (this.serverProperties.getForwardHeadersStrategy().equals(ServerProperties.ForwardHeadersStrategy.NONE)) {
 			CloudPlatform platform = CloudPlatform.getActive(this.environment);
@@ -129,4 +142,31 @@ public class UndertowWebServerFactoryCustomizer
 		return this.serverProperties.getForwardHeadersStrategy().equals(ServerProperties.ForwardHeadersStrategy.NATIVE);
 	}
 
+	private <T> void setCustomOption(ConfigurableUndertowWebServerFactory factory, String key, String value,
+			String type) {
+		Field[] fields = UndertowOptions.class.getDeclaredFields();
+		for (Field field : fields) {
+			String name = getLetterAndNumber(key);
+			if (getLetterAndNumber(field.getName()).equals(name)) {
+				Option<T> option = (Option<T>) Option.fromString(
+						UndertowOptions.class.getName() + '.' + field.getName(), getClass().getClassLoader());
+				T parsed = option.parseValue(value, getClass().getClassLoader());
+				if (type.equals("server")) {
+					customizeServerOption(factory, option, parsed);
+				}
+				else if (type.equals("socket")) {
+					customizeSocketOption(factory, option, parsed);
+				}
+				return;
+			}
+		}
+	}
+
+	private String getLetterAndNumber(String name) {
+		StringBuilder canonicalName = new StringBuilder(name.length());
+		name.chars().map((c) -> (char) c).filter(Character::isLetterOrDigit).map(Character::toLowerCase)
+				.forEach((c) -> canonicalName.append((char) c));
+		return canonicalName.toString();
+	}
+
 }

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/ServerPropertiesTests.java

@@ -214,6 +214,20 @@ class ServerPropertiesTests {
 		assertThat(this.properties.getJetty().getSelectors()).isEqualTo(10);
 	}
 
+	@Test
+	void testCustomizeUndertowServerOption() {
+		bind("server.undertow.options.server.ALWAYS_SET_KEEP_ALIVE", "true");
+		assertThat(this.properties.getUndertow().getOptions().getServer().containsKey("ALWAYS_SET_KEEP_ALIVE"));
+		assertThat(this.properties.getUndertow().getOptions().getServer().get("ALWAYS_SET_KEEP_ALIVE").equals("true"));
+	}
+
+	@Test
+	void testCustomizeUndertowSocketOption() {
+		bind("server.undertow.options.socket.ALWAYS_SET_KEEP_ALIVE", "true");
+		assertThat(this.properties.getUndertow().getOptions().getSocket().containsKey("ALWAYS_SET_KEEP_ALIVE"));
+		assertThat(this.properties.getUndertow().getOptions().getSocket().get("ALWAYS_SET_KEEP_ALIVE").equals("true"));
+	}
+
 	@Test
 	void testCustomizeJettyAccessLog() {
 		Map<String, String> map = new HashMap<>();

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/embedded/UndertowWebServerFactoryCustomizerTests.java

@@ -155,6 +155,18 @@ class UndertowWebServerFactoryCustomizerTests {
 		assertThat(boundServerOption(UndertowOptions.ALWAYS_SET_KEEP_ALIVE)).isFalse();
 	}
 
+	@Test
+	void customServerOption() {
+		bind("server.undertow.options.server.ALWAYS_SET_KEEP_ALIVE=false");
+		assertThat(boundServerOption(UndertowOptions.ALWAYS_SET_KEEP_ALIVE)).isFalse();
+	}
+
+	@Test
+	void customSocketOption() {
+		bind("server.undertow.options.socket.ALWAYS_SET_KEEP_ALIVE=false");
+		assertThat(boundSocketOption(UndertowOptions.ALWAYS_SET_KEEP_ALIVE)).isFalse();
+	}
+
 	@Test
 	void deduceUseForwardHeaders() {
 		this.environment.setProperty("DYNO", "-");
@@ -186,6 +198,14 @@ class UndertowWebServerFactoryCustomizerTests {
 		return map.get(option);
 	}
 
+	private <T> T boundSocketOption(Option<T> option) {
+		Builder builder = Undertow.builder();
+		ConfigurableUndertowWebServerFactory factory = mockFactory(builder);
+		this.customizer.customize(factory);
+		OptionMap map = ((OptionMap.Builder) ReflectionTestUtils.getField(builder, "socketOptions")).getMap();
+		return map.get(option);
+	}
+
 	private ConfigurableUndertowWebServerFactory mockFactory(Builder builder) {
 		ConfigurableUndertowWebServerFactory factory = mock(ConfigurableUndertowWebServerFactory.class);
 		willAnswer((invocation) -> {