Changing logging settings

Standard logging settings work very well for general usage.

Changing the log level can be useful for checking for bugs or understanding malfunctions due to bad configuration or strange plugin behavior. A verbose log can be used from the Elasticsearch community to solve such problems.

If you need to debug your Elasticsearch server or change how the logging works (that is, remoting send events), you need to change the log4j2.properties file.

Getting ready

You need a working Elasticsearch installation, as we described in the Downloading and installing Elasticsearch recipe, and a simple text editor to change configuration files.

How to do it…

In the config directory in your Elasticsearch install directory, there is a log4j2.properties file that controls the working settings.

The steps that are required for changing the logging settings are as follows:

1. To emit every kind of logging Elasticsearch could produce, you can change the current root level logging, which is as follows:

rootLogger.level = info

2. This needs to be changed to the following:

rootLogger.level = debug

3. Now, if you start Elasticsearch from the command line (with bin/elasticsearch -f), you should see a lot of information, like the following, which is not always useful (except to debug unexpected issues):

How it works…

The Elasticsearch logging system is based on the log4j library (http://logging.apache.org/log4j/).

Log4j is a powerful library  that's used to manage logging. Covering all of its functionalities is outside the scope of this book; if a user needs advanced usage, there are a lot of books and articles on the internet about it.