feat(logging): Add simple support for CoAP request logging (#101)

Add RequestLoggerFilter to provide request logging with customizable log message format.

coap-core/src/main/java/com/mbed/coap/server/filter/RequestLoggerFilter.java

@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2022-2024 java-coap contributors (https://github.com/open-coap/java-coap)
+ * SPDX-License-Identifier: Apache-2.0
+ * 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
+ *
+ * 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 com.mbed.coap.server.filter;
+
+import com.mbed.coap.packet.CoapRequest;
+import com.mbed.coap.packet.CoapResponse;
+import com.mbed.coap.utils.Filter;
+import com.mbed.coap.utils.Service;
+import java.util.concurrent.CompletableFuture;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.slf4j.event.Level;
+import org.slf4j.spi.LoggingEventBuilder;
+
+public class RequestLoggerFilter implements Filter.SimpleFilter<CoapRequest, CoapResponse> {
+    private final LoggingEventBuilder loggingEventBuilder;
+    private final Formatter msgFormatter;
+
+    RequestLoggerFilter(LoggingEventBuilder loggingEventBuilder, Formatter msgFormatter) {
+        this.loggingEventBuilder = loggingEventBuilder;
+        this.msgFormatter = msgFormatter;
+    }
+
+    @Override
+    public CompletableFuture<CoapResponse> apply(CoapRequest req, Service<CoapRequest, CoapResponse> service) {
+        long startTime = System.currentTimeMillis();
+        return service.apply(req).thenApply((resp) -> {
+            long endTime = System.currentTimeMillis();
+            loggingEventBuilder.log(() -> msgFormatter.apply(req, resp, endTime - startTime));
+            return resp;
+        });
+    }
+
+    @FunctionalInterface
+    public interface Formatter {
+        String apply(CoapRequest req, CoapResponse resp, long duration);
+    }
+
+    public static class Builder {
+        public final static Formatter DEFAULT_FORMATTER = (req, resp, duration) -> String.format("[%s] %s -> %s (%dms)", req.getPeerAddress(), req, resp, duration);
+
+        private Logger logger = LoggerFactory.getLogger(RequestLoggerFilter.class);
+        private Level logLevel = Level.INFO;
+        private Formatter msgFormatter = DEFAULT_FORMATTER;
+
+        public Builder logger(Logger logger) {
+            this.logger = logger;
+            return this;
+        }
+
+        public Builder logLevel(Level logLevel) {
+            this.logLevel = logLevel;
+            return this;
+        }
+
+        public Builder msgFormatter(Formatter msgFormatter) {
+            this.msgFormatter = msgFormatter;
+            return this;
+        }
+
+        public RequestLoggerFilter build() {
+            return new RequestLoggerFilter(logger.atLevel(logLevel), msgFormatter);
+        }
+    }
+}

coap-core/src/test/java/com/mbed/coap/server/filter/RequestLoggerFilterTest.java

@@ -0,0 +1,91 @@
+/*
+ * Copyright (C) 2022-2024 java-coap contributors (https://github.com/open-coap/java-coap)
+ * SPDX-License-Identifier: Apache-2.0
+ * 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
+ *
+ * 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 com.mbed.coap.server.filter;
+
+import ch.qos.logback.classic.Level;
+import ch.qos.logback.classic.Logger;
+import ch.qos.logback.classic.spi.ILoggingEvent;
+import ch.qos.logback.core.read.ListAppender;
+import com.mbed.coap.packet.CoapRequest;
+import com.mbed.coap.packet.CoapResponse;
+import com.mbed.coap.utils.Filter;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.slf4j.LoggerFactory;
+
+import java.net.InetSocketAddress;
+import java.util.concurrent.*;
+
+import static com.mbed.coap.packet.CoapRequest.get;
+import static com.mbed.coap.server.filter.RequestLoggerFilter.Builder.DEFAULT_FORMATTER;
+import static com.mbed.coap.utils.CoapRequestBuilderFilter.REQUEST_BUILDER_FILTER;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.slf4j.event.Level.DEBUG;
+
+class RequestLoggerFilterTest {
+    private Logger logger = (Logger) LoggerFactory.getLogger(RequestLoggerFilterTest.class);
+    private RequestLoggerFilter.Builder logFilterBuilder;
+    private ListAppender<ILoggingEvent> listAppender = new ListAppender<>();
+
+    @BeforeEach
+    public void beforeEach() {
+        logFilterBuilder = new RequestLoggerFilter.Builder().logger(logger);
+        logger.addAppender(listAppender);
+        listAppender.list.clear();
+        listAppender.start();
+    }
+
+    @Test
+    void defaultFormatterShouldWork() {
+        String logMsg = DEFAULT_FORMATTER.apply(get("/").address(new InetSocketAddress("1.1.1.1", 31337)).build(), CoapResponse.ok().build(), 123);
+
+        assertEquals("[/1.1.1.1:31337] CoapRequest[GET] -> CoapResponse[205] (123ms)", logMsg);
+    }
+
+    @Test
+    void shouldLogRequestAndResponseWithDefaultMessage() {
+        // given
+        Filter<CoapRequest.Builder, CoapResponse, CoapRequest, CoapResponse> filter = REQUEST_BUILDER_FILTER.andThen(logFilterBuilder.build());
+        filter.apply(
+                get("/"), __ -> CoapResponse.ok().toFuture()
+        ).join();
+
+        // then
+        ILoggingEvent logEvent = listAppender.list.get(0);
+        assertEquals(Level.INFO, logEvent.getLevel());
+        assertTrue(logEvent.getMessage().contains("GET"));
+        assertTrue(logEvent.getMessage().contains("205"));
+    }
+
+
+    @Test
+    void shouldLogRequestAndResponseWithCustomParameters() {
+        // given
+        Filter<CoapRequest.Builder, CoapResponse, CoapRequest, CoapResponse> filter = REQUEST_BUILDER_FILTER.andThen(
+                logFilterBuilder
+                        .msgFormatter((req, resp, __) -> String.format("%s %s -> %s", req.getMethod(), req.options().getUriPath(), resp.getCode().codeToString()))
+                        .logLevel(DEBUG)
+                        .build()
+        );
+        filter.apply(get("/dupa"), __ -> CoapResponse.ok().toFuture()).join();
+
+        // then
+        ILoggingEvent logEvent = listAppender.list.get(0);
+        assertEquals(Level.DEBUG, logEvent.getLevel());
+        assertEquals("GET /dupa -> 205", logEvent.getMessage());
+    }
+}