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local-app/python-tools/ipam/summarize_ipam.py

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+#!/bin/env python3
+
+import json
+import argparse
+import ipaddress
+import sys
+from datetime import datetime
+
+__version__ = "1.0.0"
+
+def get_args():
+    parser = argparse.ArgumentParser(description="Aggregate IPAM CIDRs into supernets.")
+    parser.add_argument("input_file", help="The JSON file generated by the IPAM exporter")
+    return parser.parse_args()
+
+def summarize_cidrs(input_file):
+    try:
+        with open(input_file, 'r') as f:
+            data = json.load(f)
+    except Exception as e:
+        print(f"Error reading file: {e}")
+        sys.exit(1)
+
+    # Extract CIDRs specifically from VPCs (to avoid subnet overlap issues)
+    # Using a set to handle any potential duplicate CIDR entries
+    vpc_cidrs = {item['ResourceCidr'] for item in data if item['ResourceType'] == 'VPC'}
+
+    if not vpc_cidrs:
+        print("No VPC CIDRs found in the input file.")
+        return
+
+    # Convert strings to IPv4Network objects
+    networks = []
+    for cidr in vpc_cidrs:
+        try:
+            networks.append(ipaddress.ip_network(cidr))
+        except ValueError as e:
+            print(f"Skipping invalid CIDR {cidr}: {e}")
+
+    # The 'collapse_addresses' function does the magic
+    # It returns an iterator of the most collapsed (summarized) networks
+    summarized = list(ipaddress.collapse_addresses(networks))
+
+    # Print results
+    timestamp = datetime.now().strftime("%Y%m%dT%H%M%S")
+    output_filename = f"ipam-summary.{timestamp}.txt"
+
+    with open(output_filename, 'w') as f:
+        f.write(f"# IPAM Aggregation Summary - Generated {timestamp}\n")
+        f.write(f"# Input: {input_file}\n")
+        f.write(f"# Original VPC Count: {len(vpc_cidrs)}\n")
+        f.write(f"# Summarized Block Count: {len(summarized)}\n")
+        f.write("-" * 40 + "\n")
+        for net in summarized:
+            print(net)
+            f.write(f"{net}\n")
+
+    print(f"\nSuccessfully summarized {len(vpc_cidrs)} VPCs into {len(summarized)} blocks.")
+    print(f"Results saved to: {output_filename}")
+
+if __name__ == "__main__":
+    args = get_args()
+    summarize_cidrs(args.input_file)