synapse/contrib/lnav/README.md

lnav config for Synapse logs

lnav is a log-viewing tool. It is particularly useful when you need to interleave multiple log files, or for exploring a large log file with regex filters. The downside is that it is not as ubiquitous as tools like less, grep, etc.

This directory contains an lnav log format definition for Synapse logs as emitted by Synapse with the default logging configuration. It supports lnav 0.10.1 because that's what's packaged by my distribution.

This should allow lnav:

• to interpret timestamps, allowing log interleaving;
• to interpret log severity levels, allowing colouring by log level(!!!);
• to interpret request IDs, allowing you to skip through a specific request; and
• to highlight room, event and user IDs in logs.

See also https://gist.github.com/benje/e2ab750b0a81d11920d83af637d289f7 for a similar example.

Example

Tips

• lnav -i /path/to/synapse/checkout/contrib/lnav/synapse-log-format.json
• lnav my_synapse_log_file or lnav synapse_log_files.*, etc.
• lnav --help for CLI help.

Within lnav itself:

• ? for help within lnav itself.
• q to quit.
• / to search a-la less and vim, then n and N to continue searching down and up.
• Use o and O to skip through logs based on the request ID (POST-1234, or else the value of the request_id_header header). This may get confused if the same request ID is repeated among multiple files or process restarts.
• ???
• Profit