Syslog supplier/source

- Provide TCP/UDP based syslog supplier and then generate apps based on that

applications/source/syslog-source/src/main/resources/META-INF/dataflow-configuration-metadata-whitelist.properties

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+configuration-properties.classes=org.springframework.cloud.fn.supplier.syslog.SyslogSupplierProperties
+

applications/source/syslog-source/src/main/resources/META-INF/dataflow-configuration-metadata.properties

@@ -0,0 +1,2 @@
+configuration-properties.classes=org.springframework.cloud.fn.supplier.syslog.SyslogSupplierProperties
+

applications/source/syslog-source/src/test/java/org/springframework/cloud/stream/app/source/syslog/SyslogSourceTests.java

@@ -0,0 +1,87 @@
+/*
+ * Copyright 2020-2020 the original author or authors.
+ *
+ * Licensed 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
+ *
+ *      https://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.springframework.cloud.stream.app.source.syslog;
+
+import java.net.Socket;
+import java.util.Map;
+
+import javax.net.SocketFactory;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.boot.WebApplicationType;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.builder.SpringApplicationBuilder;
+import org.springframework.cloud.fn.supplier.syslog.SyslogSupplierConfiguration;
+import org.springframework.cloud.stream.binder.test.OutputDestination;
+import org.springframework.cloud.stream.binder.test.TestChannelBinderConfiguration;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.context.annotation.Import;
+import org.springframework.integration.ip.tcp.connection.AbstractServerConnectionFactory;
+import org.springframework.messaging.Message;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class SyslogSourceTests {
+
+	private static final String RFC3164_PACKET = "<157>JUL 26 22:08:35 WEBERN TESTING[70729]: TEST SYSLOG MESSAGE";
+
+	@Test
+	public void testBasicSyslogSourceWithBinder() throws Exception {
+
+		try (ConfigurableApplicationContext context = new SpringApplicationBuilder(
+				TestChannelBinderConfiguration
+						.getCompleteConfiguration(SyslogSourceTestApplication.class))
+				.web(WebApplicationType.NONE)
+				.run("--spring.cloud.function.definition=syslogSupplier", "--syslog.supplier.port=0")) {
+
+			AbstractServerConnectionFactory connectionFactory = context.getBean(AbstractServerConnectionFactory.class);
+
+			sendTcp(RFC3164_PACKET + "\n", connectionFactory);
+
+			OutputDestination target = context.getBean(OutputDestination.class);
+			Message<byte[]> sourceMessage = target.receive(10000);
+			String actual = new String(sourceMessage.getPayload());
+			final Map map = new ObjectMapper().readValue(actual, Map.class);
+			assertThat(map.get("HOST")).isEqualTo("WEBERN");
+		}
+	}
+
+	private void sendTcp(String syslog, AbstractServerConnectionFactory connectionFactory) throws Exception {
+		int port = getPort(connectionFactory);
+		Socket socket = SocketFactory.getDefault().createSocket("localhost", port);
+		socket.getOutputStream().write(syslog.getBytes());
+		socket.close();
+	}
+
+	private int getPort(AbstractServerConnectionFactory connectionFactory) throws Exception {
+		int n = 0;
+		while (n++ < 100 && !connectionFactory.isListening()) {
+			Thread.sleep(100);
+		}
+		assertThat(connectionFactory.isListening()).isTrue();
+		int port = connectionFactory.getPort();
+		assertThat(port > 0).isTrue();
+		return port;
+	}
+
+	@SpringBootApplication
+	@Import(SyslogSupplierConfiguration.class)
+	public static class SyslogSourceTestApplication {
+	}
+}