7.4.2.7 Error Logging in JSON Format

This section describes how to configure error logging using the built-in filter, log_filter_internal, and the JSON sink, log_sink_json, to take effect immediately and for subsequent server startups. For general information about configuring error logging, see Section 7.4.2.1, “Error Log Configuration”.

To enable the JSON sink, first load the sink component, then modify the log_error_services value:

INSTALL COMPONENT 'file://component_log_sink_json';
SET PERSIST log_error_services = 'log_filter_internal; log_sink_json';

To set log_error_services to take effect at server startup, use the instructions at Section 7.4.2.1, “Error Log Configuration”. Those instructions apply to other error-logging system variables as well.

It is permitted to name log_sink_json multiple times in the log_error_services value. For example, to write unfiltered events with one instance and filtered events with another instance, you could set log_error_services like this:

SET PERSIST log_error_services = 'log_sink_json; log_filter_internal; log_sink_json';

The JSON sink determines its output destination based on the default error log destination, which is given by the log_error system variable. If log_error names a file, the JSON sink bases output file naming on that file name, plus a numbered .NN.json suffix, with NN starting at 00. For example, if log_error is file_name, successive instances of log_sink_json named in the log_error_services value write to file_name.00.json, file_name.01.json, and so forth.

If log_error is stderr, the JSON sink writes to the console. If log_sink_json is named multiple times in the log_error_services value, they all write to the console, which is likely not useful.