Small python script to make terraform plan outputs for terraform helm_release values better readable

terradiff

#!/bin/env python3

#
# TERRADIFF
#
# Small script to convert EOT diffs into single line diffs to make them easier to read
#
# How to use
# terraform plan | terradiff
#

import re
import sys
import difflib
from os import isatty

try:
    from colorama import Fore, Back, Style, init

    init()
except ImportError:  # fallback so that the imported classes always exist
    class ColorFallback():
        __getattr__ = lambda self, name: ''


    Fore = Back = Style = ColorFallback()


def color_diff(diffc):
    for line in diffc:
        if line.startswith('+'):
            yield Fore.GREEN + line + Fore.RESET
        elif line.startswith('-'):
            yield Fore.RED + line + Fore.RESET
        elif line.startswith('^'):
            yield Fore.BLUE + line + Fore.RESET
        else:
            yield line


def strip_ansi_codes(s):
    """
    Remove ANSI color codes from the string.
    """
    return re.sub('\033\\[([0-9]+)(;[0-9]+)*m', '', s)


is_pipe = not isatty(sys.stdin.fileno())

if not is_pipe:
    raise SystemExit("No input available. Please use 'command | terradiff'")

input = sys.stdin.read()

# Colored version
r = r'.\[31m(-).\[0m.\[0m (<<-EOT.*?EOT).*?.\[32m(\+).\[0m.\[0m (<<-EOT.*?EOT)'

for match in re.finditer(r, input, re.S):
    d = difflib.Differ()
    l = match.group(2)
    r = match.group(4)
    lc = strip_ansi_codes(l)
    rc = strip_ansi_codes(r)
    diff = d.compare(lc.splitlines(keepends=True), rc.splitlines(keepends=True))
    input = input.replace(match.group(0), ''.join(color_diff(diff)))

# Raw version
r = r'(-) (\<\<-EOT.*?EOT).*?(\+) (\<\<-EOT.*?EOT)'

for match in re.finditer(r, input, re.S):
    d = difflib.Differ()
    diff = d.compare(match.group(2).splitlines(keepends=True), match.group(4).splitlines(keepends=True))
    input = input.replace(match.group(0), ''.join(diff))

print(input)

Life changer! 🙌

Thanks for this. Made some upgrades for my usecase. I found that this one is pure string diff, In case there are log of changes and movements in yaml file it'll be tough to figureout what's changed and what is not.
Sorting yaml solves this, small snippet attached below to take in yaml string -> convert to dict (dicts are by default sorted) -> convert back to yaml string

def yaml_sort(d):
    try:
        x = yaml.dump(yaml.safe_load(d))
        return x
    except yaml.YAMLError:
        return d

I used it in Jenkins and colorama did not work, so I just replaced Fore.GREEN to ansi codes.
Thanks a lot!

BOLD = '\033[1m'
BLUE = '\033[36;1m'
S_GREEN = '\033[32;1m' # Strong green
RED = '\033[31;1m'
NC = '\033[0m' # No Color

def color_diff(diffc):
    for line in diffc:
        if line.startswith('+'):
            yield S_GREEN + line + NC
        elif line.startswith('-'):
            yield RED + line + NC
        elif line.startswith('^'):
            yield BLUE + line + NC
        else:
            yield line