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jl — JSON Logs

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jl is a development tool for working with structured JSON logging.

Modern applications quite often use structured logging instead of simple log messages. This is preferable for computer systems but not for humans. jl will help development by translating structured message into old-fashioned log lines.

Examples

A code snippets says more than a thousand words:

$ myprogram
{"message": "Hello, world!!", "severity": "info"}
{"message": "skipping file", "severity": "warn", "file": "empty.txt"}

$ myprogram | jl
   INFO: Hello, world!!
WARNING: skipping file [file=empty.txt]

(more examples)

Installation

macOS:

$ brew install koenbollen/public/jl
$ echo '{"msg": "It works!"}' | jl
It works!

Linux:

$ curl -LO https://github.com/koenbollen/jl/releases/download/v1.4.0/jl_linux_amd64
$ sudo install jl_linux_amd64 /usr/bin/jl && rm jl_linux_amd64
$ echo '{"msg": "It works!"}' | jl
It works!

Others:

Alternatively you can fetch a binary from the latest release or install the latest development version from source: go install github.com/koenbollen/jl@latest (requires Go 1.17+).

Usage

Usage:
  jl [options] [FILE...]

Options:
  -h, --help    Show this screen.
  --version     Show version.

Output Options:
  --color           Force colorized output
  --no-color        Don't colorize output
  --skip-prefix     Skip printing truncated bytes before the JSON
  --skip-suffix     Skip printing truncated bytes after the JSON

Formatting Options:
  --skip-fields     Don't output misc json keys as fields
  --max-field-length <int> Any field, exceeding the given length (including field name) will be ommitted from output. Use 0 to remove the length limit [default: 30]
  --include-fields <fields>, -f <fields> Always include these json keys as fields, no matter the length (comma separated list)
  --exclude-fields <fields> Always exclude these json keys (comma separated list)

You can add any option to the JL_OPTS environment variable, ex:
  export JL_OPTS="--no-color"

Compatibility

jl tries to dynamically parse the lines to support as many well known formats as possible.

Is jl not compatible with your structured logging? Please let me know by creating an issue.