convert JSON to Key-Value

flatten_json.py

#! /usr/bin/env python3
#
# script to convert JSON documents into plain key-value lines,
# formatted to be piped to zabbix_sender
#
# 20130927, martin.schuette@deck36.de
# 20200409, info@mschuette.name, change to Python 3
#
import json
import sys
import types
import os
import argparse
import re


# some formatting
def format_string(s):
    if s is None:
        return "0"
    elif isinstance(s, str) and " " in s:
        return '"%s"' % ("\\n".join(s.splitlines()),)
    elif isinstance(s, str) and s == "":
        return '""'
    elif isinstance(s, bool) and s:
        return 1
    elif isinstance(s, bool) and not s:
        return 0
    else:
        return s


# recursively flatten the document keys:
def flatten_level(doc):
    # start with some aux. functions:
    def is_leaf(doc):
        return not (isinstance(doc, list) or isinstance(doc, dict))

    def flatten_list(l):
        outlist = []
        for (num, sub) in enumerate(l):
            if is_leaf(sub):
                line = "%s %s" % (num, format_string(sub))
                outlist.append(line)
            else:
                for subitem in flatten_level(sub):
                    line = "%s.%s" % (num, subitem)
                    outlist.append(line)
        return outlist

    def flatten_dict(d):
        outlist = []
        for (key, sub) in list(d.items()):
            if is_leaf(sub):
                line = "%s %s" % (key, format_string(sub))
                outlist.append(line)
            else:
                for subitem in flatten_level(sub):
                    line = "%s.%s" % (key, subitem)
                    outlist.append(line)
        return outlist

    if is_leaf(doc):
        return format_string(doc)
    elif isinstance(doc, list):
        return flatten_list(doc)
    elif isinstance(doc, dict):
        return flatten_dict(doc)


# parse command line arguments:
parser = argparse.ArgumentParser(
    description="flatten a JSON document into key-value lines, suitable for Zabbix"
)
parser.add_argument("-p", "--prefix", help="prefix for zabbix keys")
parser.add_argument(
    "-a", "--attribute", help="attribute for zabbix keys (e.g. key[attribute])"
)
parser.add_argument(
    "-d",
    "--dash",
    help="prepend every line with a dash, useful to pipe data into zabbix_sender",
    action="store_true",
)
parser.add_argument("-f", "--filter", help="field name(s) to filter", action="append")
parser.add_argument(
    "-i", "--infile", help="input file", type=argparse.FileType("r"), default=sys.stdin
)
args = parser.parse_args()

# read JSON:
try:
    doc = json.load(args.infile)
except ValueError:
    # silently fail if input is no valid JSON
    sys.exit(1)

# do work:
l = flatten_level(doc)
# filter output:
if args.filter:
    for f in args.filter:
        l = [x for x in l if not re.search(r"\b" + f, x)]
if args.prefix:
    l = [".".join([args.prefix, x]) for x in l]
if args.attribute:
    l = [x.replace(" ", "[%s] " % (args.attribute,), 1) for x in l]
if args.dash:
    l = ["- " + x for x in l]
print((os.linesep.join(l)))