reset a listener rule and target groups

fix_traffic_shift.py

#!/usr/bin/env python3
"""
Set a listener rule to send 100% of traffic to one target group and
0% to another target group.

Fill in the three values below and run:  python3 set_traffic_weight.py
"""

import boto3

# ---- INPUT: fill these in ----
LISTENER_RULE_ARN = "arn:aws:elasticloadbalancing:REGION:ACCOUNT:listener-rule/app/..."
ACTIVE_TARGET_GROUP_ARN = "arn:aws:elasticloadbalancing:REGION:ACCOUNT:targetgroup/active-tg/..."   # gets 100%
INACTIVE_TARGET_GROUP_ARN = "arn:aws:elasticloadbalancing:REGION:ACCOUNT:targetgroup/inactive-tg/..." # gets 0%
# --------------------------------

client = boto3.client("elbv2")

client.modify_rule(
    RuleArn=LISTENER_RULE_ARN,
    Actions=[
        {
            "Type": "forward",
            "ForwardConfig": {
                "TargetGroups": [
                    {"TargetGroupArn": ACTIVE_TARGET_GROUP_ARN, "Weight": 100},
                    {"TargetGroupArn": INACTIVE_TARGET_GROUP_ARN, "Weight": 0},
                ]
            },
        }
    ],
)

print("Done. 100% -> active TG, 0% -> inactive TG.")