To pretty-print logs of JSON. Can be used like: `docker-compose logs -f myapp | json_pp_stream.py`. Made a Go version as well: https://github.com/gaqzi/log-viewer/

json_pp_stream.py

#!/usr/bin/env python3
import json
import sys

try:
    from pygments import highlight, lexers, formatters


    def json_formatter(line: str) -> str:
        return highlight(line, lexers.JsonLexer(), formatters.TerminalFormatter())
except ImportError:
    def json_formatter(line: str) -> str:
        return line


def pp_line(line: str) -> str:
    original = line
    prefix = ""

    if line[0] != "{":
        split = line.split(" : ", maxsplit=1)
        if len(split) == 2:
            prefix, line = split

    line = line.lstrip()
    if line[0] != "{":
        return original.rstrip()

    output = []
    indent = "    "
    for line in json.dumps(json.loads(line), indent=4).splitlines():
        output.append(f"{indent}{line}")

    return f"{prefix}\n" + json_formatter('\n'.join(output))


if __name__ == '__main__':
    for line in sys.stdin:
        print(pp_line(line))