synapse-old/contrib/lnav/README.md

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# `lnav` config for Synapse logs
[lnav](https://lnav.org/) 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](
https://docs.lnav.org/en/v0.10.1/formats.html#defining-a-new-format
) for Synapse logs as
emitted by Synapse with the default [logging configuration](
https://matrix-org.github.io/synapse/latest/usage/configuration/config_documentation.html#log_config
). 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
[![asciicast](https://asciinema.org/a/556133.svg)](https://asciinema.org/a/556133)
## 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`](
https://matrix-org.github.io/synapse/latest/usage/configuration/config_documentation.html?highlight=request_id_header#listeners
) header). This may get confused if the same request ID is repeated among
multiple files or process restarts.
- ???
- Profit