flog

README

flog

Filter logs on their serverity, with automatic detection of log formats

Sample usage

Sample Go app using sirupsen/logrus

$ go run main.go
TRAC[0000] A walrus appears                              animal=walrus
DEBU[0000] A walrus appears                              animal=walrus
INFO[0000] A walrus appears                              animal=walrus
WARN[0000] A walrus appears                              animal=walrus
ERRO[0000] A walrus appears                              animal=walrus
FATA[0000] A walrus appears                              animal=walrus

$ go run main.go | flog -s warn
flog: Omitted 1 Trace, 1 Debug, 1 Information.
WARN[0000] A walrus appears                              animal=walrus
ERRO[0000] A walrus appears                              animal=walrus
FATA[0000] A walrus appears                              animal=walrus

Sample .NET app using Microsoft.Extensions.Logging.Console

Yes, this includes multiline logs, such as those pesky .NET logs:

$ dotnet run
trac: Program[0]
      Sample log
dbug: Program[0]
      Sample log
info: Program[0]
      Sample log
warn: Program[0]
      Sample log
fail: Program[0]
      Sample log

$ dotnet run | flog -s warn
flog: Omitted 1 Trace, 1 Debug, 1 Information.
warn: Program[0]
      Sample log
fail: Program[0]
      Sample log

Command-line interface

$ flog --help
Usage: flog [<paths> ...]

Use flog to filter logs on their serverity (even multiline logs), with automatic detection of log
formats.

flog Copyright (C) 2021 Kalle Jillheden

    License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>
    This program comes with ABSOLUTELY NO WARRANTY; for details run 'flog --license-w'.
    This is free software, and you are welcome to redistribute it
    under certain conditions; run 'flog --license-c' for details.

Arguments:
  [<paths> ...]    File(s) to read logs from. Uses STDIN if unspecified

Flags:
  -h, --help                     Show context-sensitive help.
  -s, --min=info                 Omit logs below specified severity (exclusive)
  -S, --max=none                 Omit logs above specified severity (exclusive)
  -t, --since=STRING             Omit logs timestamped before a specific time (or relative time period
                                 ago) [Not yet implemented]
  -t, --before=STRING            Omit logs timestamped after a specific time (or relative time period
                                 ago) [Not yet implemented]
  -e, --exclude=EXCLUDE,...      Omit logs of specified severity (can be specified multiple times)
  -i, --include=INCLUDE,...      Omit logs of severity not specified with this flag (can be specified
                                 multiple times)
  -q, --quiet                    Omit the 'omitted logs' messages. Shorthand for --verbose=0.
  -v, --verbose=1                Enable verbose output (can be specified up to 2 times, ex: --verbose=2
                                 or -vv)
      --version                  Show the version of the program and then exit.
      --completions-install      Install shell completions
      --completions-uninstall    Uninstall shell completions
      --license-c                Show the programs license conditions and then exit. (Warn: a lot of
                                 text)
      --license-w                Show the programs warranty and then exit.

Severities:
  Undefined      0, n, nil, null, none, unde, undefined
  Unknown        1, ?, u, ukwn, unkn, unknown
  Trace          2, t, tra, trac, trce, trace
  Debug          3, d, deb, debu, debg, dbug, debug
  Information    4, i, inf, info, information
  Warning        5, w, wrn, warn, warning
  Error          6, e, err, erro, errr, error
  Critical       7, c, crt, crit, critical
  Fatal          8, f, fata, fatl, fatal
  Panic          9, p, pan, pnc, pani, panic

Installation

1. Head over to the latest release https://github.com/jilleJr/flog/releases/latest

2. Down in the "Assets", find the one that matches your OS and architecture, and download it.

3. Save it to a location you have added to your $PATH, for example ~/.local/bin

4. Make sure to just rename it to flog (or flog.exe for Windows users).

5. Done!

If your OS or architecture is missing from the list, then create an issue on it and I'll make sure to build it to your architecture when I release a new build.

Main use case

Searching through logs in Kubernetes. For example, to find any error logs in Kubernetes logs you'd usually have to use grep with some extreamly high context so that you get a glimpse of what the error was about.

With flog you can just run:

$ kubectl logs name-of-my-pod | flog -s err

And there you have it.

Building from source

1. Install Go

2. Run the following (outside of a Go project) to build the latest release

   The -u flag updates the package if you've already the package installed.

   $ go get -u github.com/jilleJr/flog
   

   Or if you want to build the latest unreleased version from the main branch then clone the repo and run go install or make install: (No sudo is required)

   $ git clone https://github.com/jilleJr/flog
   $ cd flog
   $ make install
   

Releasing

1. Install Go & Make

2. Run the following to generate the executables into the bin/ directory

   $ make release
   

3. Update the date in CHANGELOG.md, for example changing

   diff --git a/CHANGELOG.md b/CHANGELOG.md
   index 9622e17..18ce396 100644
   --- a/CHANGELOG.md
   +++ b/CHANGELOG.md
   @@ -6,7 +6,7 @@ This project tries to use [SemVer 2.0.0](https://semver.org)
        Remember to update the version.go file whenever you add a new version.
    -->
   
   -## v0.3.0 (WIP)
   +## v0.3.0 (2020-02-13)
   
    - Added debug logging, enabled by specifying `-vv` or `--verbose=2`. (#13)
   
   

4. Create a Git tag

   $ git tag v0.3.0 -m "flog v0.3.0"
   
   $ git push --follow-tags
   

5. Create a GitHub release of the Git tag and upload the binaries to that release

License

All code in this repository is licensed under GNU GPLv3. Full license can be found inside the LICENSE file.