generate-moved-blocks.py

from Levenshtein import distance
import subprocess
import re
import sys
import pprint

print("Running terraform plan...", file=sys.stderr)


proc = subprocess.run(
    ["terraform", "plan", "-no-color"],
    capture_output=True,
    text=True,
    check=True,
)

print("Parsing output...", file=sys.stderr)

find_modification = re.compile(
    r"(?P<resource>[^ ]+) will be (?P<cord>created|destroyed)")


created = []
destroyed = []

for line in proc.stdout.split("\n"):
    if '#' in line:
        print(f"line: `{line}`", file=sys.stderr)
    m = find_modification.search(line)
    if m:
        if m.group("cord") == "created":
            created.append(m.group("resource"))
        else:
            destroyed.append(m.group("resource"))

print(f"Matched {len(created)} creations and {len(destroyed)} destructions.",
      file=sys.stderr)

print("Computing Levenshtein Distances...", file=sys.stderr)
moved = {}
for d in destroyed:
    others = []
    for c in created:
        others.append((distance(d, c), c))
    others.sort(key=lambda tuple: tuple[0])
    if len(others) > 0:
        moved[d] = others[0][1]


print("Writing moved blocks...", file=sys.stderr)

for d, c in moved.items():
    print(
        f"""
moved {"{"}
  from = {d}
  to = {c}
{"}"}
"""
    )