Create a script to format JSON logs

Here’s a simple and customizable Python script to format JSON logs for readability. It takes raw JSON log lines (either from a file or standard input), parses them, and prints them in a human-readable format.

python
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import json
import sys
import argparse

def format_json_log_line(line, indent=4):
    try:
        log_entry = json.loads(line)
        formatted = json.dumps(log_entry, indent=indent, ensure_ascii=False)
        return formatted
    except json.JSONDecodeError:
        return f"Invalid JSON: {line.strip()}"

def process_file(file_path, indent=4):
    with open(file_path, 'r', encoding='utf-8') as f:
        for line in f:
            formatted = format_json_log_line(line, indent)
            print(formatted)
            print('-' * 80)  # separator between entries

def process_stdin(indent=4):
    print("Reading from stdin. Press Ctrl+D (Linux/macOS) or Ctrl+Z (Windows) to stop.")
    for line in sys.stdin:
        formatted = format_json_log_line(line, indent)
        print(formatted)
        print('-' * 80)

if __name__ == "__main__":
    parser = argparse.ArgumentParser(description="Format JSON log entries for readability.")
    parser.add_argument('-f', '--file', help="Path to the log file containing JSON lines.")
    parser.add_argument('-i', '--indent', type=int, default=4, help="Number of spaces for indentation.")
    
    args = parser.parse_args()

    if args.file:
        process_file(args.file, args.indent)
    else:
        process_stdin(args.indent)

Features:

• Supports reading from a file or standard input

• Pretty-prints valid JSON with configurable indentation

• Identifies and flags invalid JSON lines

• Adds a visual separator for better readability

Usage:

1. Save it as json_log_formatter.py

2. Run from command line:

bash
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# Format a log file
python json_log_formatter.py --file mylogs.json

# Format with 2-space indentation
python json_log_formatter.py --file mylogs.json --indent 2

# Or use it with piped logs
cat mylogs.json | python json_log_formatter.py

Let me know if you want an extended version with colorized output or filtering.