The Log Writer plugin or Logger for short, allows the creation of log files to store server events and register the status of each incoming HTTP request. It's designed to work with an in-memory buffer allowing flushing back the data to the file system at certain intervals of time.
To enable the Logger plugin, please follow the steps mentioned on Plugins section. The plugin name is monkey-logger.so, so make sure the plugin entry is Load and the absolute path is correct.
The plugin allows to register events at two scopes:
|global||Defines the general behavior of the Plugin.|
|virtual host||Specific Log rules for the Virtual Host in question|
Is suggested to enabled both:
The Global configuration scope takes place in the main plugin configuration file, it can be found at conf/plugins/logger/logger.conf, it schema contains the [LOGGER] section and allows the following entries:
|FlushTimeout||Set the number of seconds to wait before to flush to disk. Default value is 3 seconds.|
|MasterLog||Specify the log file that will store Server events when working in daemon mode, it must be a path where the server have write access.|
[LOGGER] FlushTimeout 3 MasterLog /home/foo/monkey/logs/master.log
The example above sets that all Log buffers will flush to the filesystem after three seconds and for every Server event, it will be stored on the given path on MasterLog key.
The Virtual Host configuration scope, allow to define where each successful/error request for the given host will be stored. The following configuration takes place inside each Virtual Host file and the schema contains the [LOGGER] section allowing the following entries:
|AccessLog||Define the absolute path where HTTP requests that were successful will be registered.|
|ErrorLog||Define the absolute path where HTTP requests that failed will be registered.|
Note that each given path must be writable by Monkey Server, otherwise the server will start triggering errors at flushing time.
An example of the configuration inside a Virtual Host is as follows:
[LOGGER] AccessLog /home/foo/monkey/logs/access.log ErrorLog /home/foo/monkey/logs/error.log
Every successful request will be registered on the path given for access.log file, for the opposite case, the error.log file will be used. If some key is missing, the event will not be considered by Logger.
In technical terms, for each Virtual Host the Logger plugin creates a buffer based on a Linux Kernel Pipe for each type (access/error), the common buffer size is about 65KB and for each event the running thread dispatch the log entry to the Pipe. On the other side exists a worker thread that consume the Pipes data once it reach the FlushTimeout or a Pipe capacity is near of it 90% of usage, on that moment it flush to disk each log.
For short, it runs in a lock-free mechanism without affect performance.