krapslog

Visualize a log file with sparklines

When troubleshooting a problem with a production service, I often need to get the general shape of a log file. Are there any spikes? Was the load higher during the incident than it was beforehand? Does anything else stand out? Without tooling to help you, a large log file is little more than a blob of data. This tool is designed to quickly surface key features of the log — and then get out of your way.

Installing

Homebrew

brew install acj/taps/krapslog

From source

cargo install krapslog

Usage

$ krapslog --help
Visualize log files using sparklines

Usage: krapslog [OPTIONS] [FILE]

Arguments:
  [FILE]  Log file to analyze

Options:
  -F, --format <FORMAT>            Timestamp format to match [default: %d/%b/%Y:%H:%M:%S%.f]
  -m, --markers <MARKERS>          Number of time markers to display [default: 0]
  -h, --height <HEIGHT>            Height (in lines) of the displayed sparkline [default: 1]
  -c, --concurrency <CONCURRENCY>  Number of threads to use when processing large files (defaults to number of CPU cores) [default: 8]
  -h, --help                       Print help
  -V, --version                    Print version

Examples

Get the basic shape:

$ krapslog /var/log/haproxy.log 
▂▂▂▂▂▁▂▁▁▁▁▂▁▁▁▁▂▂▂▁▁▁▁▁▁▁▁▁▂▂▂▂▂▂▂▂▂▃▂▂▂▃▂▂▂▂▃▃▃▃▃▄▅▅▅▄▅▃▄▃▄▄▅▅▆▇▆▆▆▆▆▆▆▆▇▇▇▇██

Add points in time:

$ krapslog --markers 10 /var/log/haproxy.log
                                                             Sat Nov 23 14:15:56
                                                    Sat Nov 23 13:22:29        |
                                           Sat Nov 23 12:29:01        |        |
                                  Sat Nov 23 11:35:33        |        |        |
                          Sat Nov 23 10:48:02       |        |        |        |
                                            |       |        |        |        |
▂▂▂▂▂▁▂▁▁▁▁▂▁▁▁▁▂▂▂▁▁▁▁▁▁▁▁▁▂▂▂▂▂▂▂▂▂▃▂▂▂▃▂▂▂▂▃▃▃▃▃▄▅▅▅▄▅▃▄▃▄▄▅▅▆▇▆▆▆▆▆▆▆▆▇▇▇▇██
|        |        |       |        |
|        |        |       |        Sat Nov 23 09:54:34
|        |        |       Sat Nov 23 09:01:07
|        |        Sat Nov 23 08:13:36
|        Sat Nov 23 07:20:08
Sat Nov 23 06:26:40

Increase the display resolution:

$ krapslog --height 5 /var/log/haproxy.log
                                                                                        ▁           ▁  ▁▃▃██
                                                                                    ▁ ▁▅█▃▅▂▂▄▃▃▅▅▇▆█▇██████
                                                                     ▁▆▅▇▅▃▆▇  ▁ ▁▁▄█▇██████████████████████
                                            ▁▁ ▁▂ ▅▂  ▂▃▂▁ ▃▁ ▂▂▅▅▂▄▅████████▇▆█▅███████████████████████████
▇▇▇▆▇▇▅▅▆▅▅▄▃▄▄▇▄▆▃▅▄▅▅▆▅▅▃▁▁▃▃▄▄▄▃▄▅▅▆█▅▅▇▅██▇██████▇████▇█████████████████████████████████████████████████

Integrate with other tools:

$ zcat /var/log/haproxy.log.1.gz | grep -v "unimportant.html" | krapslog
▂▁▂▁▂▁▂▂▂▁▃▁▁▁▁▁▁▁▁▁▁▁▂▂▁▁▂▃▂▂▃▁▂▁▂▂▂▂▁▂▁▂▄▂▂▂▂▂▂▂▃▂▂▂▂▄▃▃▄▃▃▃▃▄▄▄▄▄▃▄▄▅▄▃▄▄▅▅▅▅

Custom date formats

By default, krapslog assumes that log timestamps are in the Common Log Format (CLF), which looks like this: "02/Jan/2006:15:04:05.000" (timezone offset is ignored). However, you can use the format parameter to find timestamps in other formats. The parameter value must use a format that's recognized by strftime.

For example, if your log contains dates that look like "Jan 1, 2020 15:04:05", you can run krapslog as follows:

krapslog --format "%b %d, %Y %H:%M:%S" ...

Currently supported specifiers

Specifier	Meaning
%Y	The full proleptic Gregorian year, zero-padded to 4 digits.
%C	The proleptic Gregorian year divided by 100, zero-padded to 2 digits.
%y	The proleptic Gregorian year modulo 100, zero-padded to 2 digits.
%m	Month number (01--12), zero-padded to 2 digits.
%b	Abbreviated month name. Always 3 letters.
%B	Full month name. Also accepts corresponding abbreviation in parsing.
%h	Same as %b.
%d	Day number (01--31), zero-padded to 2 digits.
%H	Hour number (00--23), zero-padded to 2 digits.
%M	Minute number (00--59), zero-padded to 2 digits.
%S	Second number (00--60), zero-padded to 2 digits.
%.f	Similar to .%f but left-aligned. These all consume the leading dot.
%s	UNIX timestamp. Seconds since 1970-01-01 00:00 UTC.

Contributing

Please be kind. We're all trying to do our best.

If you find a bug, please open an issue. (Or, better, submit a pull request that fixes it!)

If you'd like see a new feature or would like to add one yourself, please open an issue so that we can discuss it.