Inserting log requests into the application code requires a fair amount of planning and effort. Observation shows that approximately 4 percent of code is dedicated to logging. Consequently, even moderately sized applications will have thousands of logging statements embedded within their code. Given their number, it becomes imperative to manage these log statements without the need to modify them manually.
This page focuses primarily on configuring Log4j through a configuration file. Information on programmatically configuring Log4j can be found at Extending Log4j 2 and Programmatic Log4j Configuration. Note that unlike Log4j 1. Log4j has the ability to automatically configure itself during initialization. When Log4j starts it will locate all the ConfigurationFactory plugins and arrange them in weighted order from highest to lowest. An example application named MyApp that uses log4j can be used to illustrate how this is done.
MyApp begins by importing log4j related classes. It then defines a static logger variable with the name MyApp which happens to be the fully qualified name of the class. Log4j will provide a default configuration if it cannot locate a configuration file. The default configuration, provided in the DefaultConfiguration class, will set up:. As was described previously, Log4j will first attempt to configure itself from configuration files.
A configuration equivalent to the default would look like:. Once the file above is placed into the classpath as log4j2. Changing the root level to trace will result in results similar to:. Simply changing the log level would not accomplish the task. Instead, the solution is to add a new logger definition to the configuration:. With this configuration all log events from com.This ensures that Tomcat's internal logging and any web application logging will remain independent, even if a web application uses Apache Commons Logging.
To configure Tomcat to use an alternative logging framework for its internal logging, follow the instructions provided by the alternative logging framework for redirecting logging for applications that use java. Keep in mind that the alternative logging framework will need to be capable of working in an environment where different loggers with the same name may exist in different class loaders.
The logging frameworks used by different web applications are independent. See class loading for more details. The exception to this rule is java. If it used directly or indirectly by your logging library then elements of it will be shared across web applications because it is loaded by the system class loader.
Apache Tomcat 9
Apache Tomcat has its own implementation of several key elements of java. This implementation is called JULI. The key component there is a custom LogManager implementation, that is aware of different web applications running on Tomcat and their different class loaders.
It supports private per-application logging configurations. It is also notified by Tomcat when a web application is unloaded from memory, so that the references to its classes can be cleared, preventing memory leaks. This java. The Apache Tomcat startup scripts do this for you, but if you are using different tools to run Tomcat such as jsvc, or running Tomcat from within an IDEyou should take care of them by yourself.
More details about java. The calls to javax. Such messages are logged to the category named. This logging is performed according to the Tomcat logging configuration.
You cannot overwrite it in a web application. The Servlets logging API predates the java. As such, it does not offer you much options. It can be noted, though, that in Apache Tomcat implementation the calls to ServletContext. The calls to ServletContext. When running Tomcat on unixes, the console output is usually redirected to the file named catalina. The name is configurable using an environment variable. See the startup scripts. Whatever is written to System. That may include:. When running as a service on Windows, the console output is also caught and redirected, but the file names are different.
The default logging configuration in Apache Tomcat writes the same messages to the console and to a log file. This is great when using Tomcat for development, but usually is not needed in production. Old applications that still use System. If the attribute is set to truethe calls to System.
Notethat the swallowOutput feature is actually a trick, and it has its limitations.A Valve element represents a component that will be inserted into the request processing pipeline for the associated Catalina container EngineHostor Context.
Individual Valves have distinct processing capabilities, and are described individually below. Access logging is performed by valves that implement org. AccessLog interface. The Access Log Valve creates log files in the same format as those created by standard web servers. These logs can later be analyzed by standard log analysis tools to track page hit counts, user session activity, and so on.
This Valve uses self-contained logic to write its log files, which can be automatically rolled over at midnight each day.
The essential requirement for access logging is to handle a large continuous stream of data with low overhead.
This Valve does not use Apache Commons Logging, thus avoiding additional overhead and potentially complex configuration. Some requests may be handled by Tomcat before they are passed to a container.
Where Tomcat cannot identify the Context that would have handled the request, e. Tomcat will use the first AccessLog implementation found to log those requests that are rejected before they are passed to a container. The output file will be placed in the directory given by the directory attribute. The name of the file is composed by concatenation of the configured prefixtimestamp and suffix. The format of the timestamp in the file name can be set using the fileDateFormat attribute.
This timestamp will be omitted if the file rotation is switched off by setting rotatable to false. Warning: If multiple AccessLogValve instances are used, they should be configured to use different output files.Apache Log4j configuration in Java Project
If sendfile is used, the response bytes will be written asynchronously in a separate thread and the access log valve will not know how many bytes were actually written. In this case, the number of bytes that was passed to the sendfile thread for writing will be recorded in the access log valve.
Flag to determine if logging will be buffered. If set to falsethen access logging will be written after each request. Default value: true. Java class name of the implementation to use.
This MUST be set to org. AccessLogValve to use the default access log valve. The same as conditionUnless. This attribute is provided for backwards compatibility. Turns on conditional logging.You probably already have implemented logging in your web applications, and may not see why you should worry about configuring loggers for Tomcat's internals.
However, spending some time familiarizing yourself with the logging options available in Tomcat can save you valuable time if you find yourself dealing with an unexpected issue. Here's a rundown of the most common Tomcat logging frameworks, configurations, and concerns, to help you get started on adding a functional logging system to your administrative toolkit today. Tip: Logging, diagnostics, error-free deployment, and advanced application provisioning can be done for your entire Tomcat infrastructure all in one console.
Try Tcat today! As of Tomcat 5. JCL is a lightweight API for Java applications that allows hierarchical logging to be supported across all log levels, independent of logging implementation. Although all JDKs ship with logging functionality provided by java. To get around this limitation, Tomcat replaces the default LogManager with JULI, a modified implementation with a number of additional features for handling containers. The most notable of JULI's extended functionalities is the ability to set property files on a per-classloader basis.
This feature makes redeployment of web applications significantly less labor-intensive. Here's a look at all the layers at which JULI's logging can be configured, including both layers standard to java. JULI uses similar configuration syntax to that used by java. Very detailed documentation on the default java. Simple examples of the logging. In other words, even though Tomcat is configured to use JULI logging out of the box, if you're at all interested in building a more elegant logging system for your site, you should consider switching to Log4J.
Here's a basic guide to getting Log4J up and running on Tomcat. Now that Tomcat is ready to work with Log4J, download the logger from the project website, and place "log4jx. Just two more steps to go. Since you won't be using logging. Eventually, you'll want to modify this file to take advantage of the many features Log4J will make available to you, but for now you can just use the basic configuration recommended by Apache.
This will generate "tomcat. Log4J uses Engine and Host names enclosed in square brackets to allow very specific levels of logging for different components. Here's an example of this syntax in action provided in the Apache Tomcat documentation:. You can also use this syntax and configuration layout on a per-application basis by including a custom "log4j. Register for free. Home Apache Tomcat resources A simple guide to Tomcat logging. An overview of Tomcat logging As of Tomcat 5.
This allows you to create separate configurations for each of your web applications with lifecycles equivalent to the given application, in addition to your core Tomcat logging configuration.
A list of a logger's handlers can be defined using the property loggerName. The loggerName. By default, this feature is disabled. Logger buffering can be configured on a per-handler basis using the bufferSize property.The Lucee Installer does not come with ability to rotate logs built into it.
Instead, the Lucee installers ship with Tomcat's default logging mechanism, java. This is simple and effective logging that will work in most situations, but if you want more complex features, such as rotation based on date or size, you will need to upgrade Tomcat to use a more advanced logging mechanism, such as Log4j. Download a couple things here, tweak a config file there, and you're all set. The following is intended to be a guide on how to go about downloading and installing log4J on a system that was built using the Lucee Installers.
If you installed Lucee to a different location, you will need to update the example directories to match where you installed Lucee. In the following example, I will be upgrading a Lucee 5 installation on Ubuntu If you're not running this setup or if you're running on Windowsyou may need to interpolate these commands a bit, but the general principals will be the same.
Start out by creating the directories that we'll need for our log4j files. Using this directory as a base, we now need to create our log4j directories:. Now that we have the directories we need, we will want to download and extract the log4j JAR's into the lib directory.
The download page is here. At the time of this writing, the most recent version is 2. There are several formats that we can use for our Log4j2 config file, but for our purposes, we'll be using XML at the moment.
Here is an example XML file that is a good place to get started:. Now that the files and configs are in place, we just need to load the Log4j JAR's at startup.
We can do that by adding the following line to the setenv.
You should see new logs like catalina. Knowledge Base. Page tree. Browse pages. A t tachments 8 Page History. Jira links. Created by Jordan Mlast modified on Oct 25, Create the log4j directories Start out by creating the directories that we'll need for our log4j files. No labels.You must take particular care when using Log4j or any other logging framework within a Java EE web application.
It's important for logging resources to be properly cleaned up database connections closed, files closed, etc. Because of the nature of class loaders within web applications, Log4j resources cannot be cleaned up through normal means.
Log4j must be "started" when the web application deploys and "shut down" when the web application undeploys. How this works varies depending on whether your application is a Servlet 3.
In either case, you'll need to add the log4j-web module to your deployment as detailed in the Maven, Ivy, and Gradle Artifacts manual page. To avoid problems the Log4j shutdown hook will automatically be disabled when the log4j-web jar is included. Log4j allows the configuration file to be specified in web. Log4j will search for configuration files by:. A Servlet 3.
Of course, the application must also be running in a compatible web container. Some examples are: Tomcat 7. Log4j 2 "just works" in Servlet 3. It is capable of automatically starting when the application deploys and shutting down when the application undeploys.
Important Note! For performance reasons, containers often ignore certain JARs known not to contain TLDs or ServletContainerInitializers and do not scan them for web-fragments and initializers. This has been fixed in Tomcat 7. You may need to do something similar on other containers if they skip scanning Log4j JAR files. The Log4j 2 Web JAR file is a web-fragment configured to order before any other web fragments in your application.
These classes properly initialize and deinitialize the Log4j configuration. For some users, automatically starting Log4j is problematic or undesirable.How-to configure Log4j on Tomcat is described in the Tomcat documentationbut the documentation sample configuration is not correct. A big advantage is that if an application uses Log4j then we can configure the logging at a central place for the Tomcat instance.
And another advantage is we can use our knowledge on how to configure Log4j logging and we don't have to learn Tomcat's syntax extensions to the JUL logging configuration.
First we must add same extra JAR files to our Tomcat classpath. And of course we must add the Log4j library to the classpath. These files are not in the normal distribution of Tomcat, but we can download them from the website. On the download page we must select the Browse link.
We place the tomcat-juli. The file tomcat-juli-adapters. Next we download the latest log4j 1. We must unpack the downloaded file to a directory on our computer.
A simple guide to Tomcat logging
Next we copy from the directory with the extracted file we downloaded the file log4j Our classpath is now setup and we can add our Log4j configuration file. First we disable the old Tomcat JUL logging configuration. The name of the file is logging. Tomcat cannot use the file for configuration, but we still have a backup.
With the old configuration out of the way we can create a new Log4j configuration file. If we look at the sample configuration file in the Tomcat documentation we notice the file contains errors. For example the conversionPattern is not configured on the layout property. We can use the following sample Log4j configuration:. We can move the log4j.
Then we must use the system property -Dlog4j. February 9, Configure Log4j on Tomcat.