asg-enforce-launch-configs.sh

#!/bin/bash

while true; do
    echo; 
    as-describe-auto-scaling-groups --show-long | awk '!/batch-/' | tee all-asg-desc
    
    aws autoscaling describe-auto-scaling-groups > all_asgs.json
    cat all_asgs.json | underscore process '
        _.filter(map(data.AutoScalingGroups, function (asg) {
            var dlc = asg.LaunchConfigurationName,
                insNeedReplace = [];
            _.each(asg.Instances, function (ins) {
                if (ins.LaunchConfigurationName != dlc) {
                    insNeedReplace.push(ins);
                }
            })
            return {
                AutoScalingGroupName: asg.AutoScalingGroupName, 
                DesiredCapacity: asg.DesiredCapacity,
                LaunchConfigurationName: dlc,
                InstancesToTerminate: insNeedReplace
            };
        }), function (asg) {
            return asg.InstancesToTerminate.length > 0;
        });
    '

    echo; 
    date;

    cat all-asg-desc | awk 'BEGIN{FS=","}{if ($1 == "AUTO-SCALING-GROUP") { A=$2; C=$3; D=$10; K=0; } if ($1 == "INSTANCE" && $7 != C && K++ < (D>8?4:(D>4?2:1))) print (D>1 ? A"\tterminate-instance\t"$2 : A"\tincrease-capacity\t"(D+1)); }' | tee rolling-tasks

    if [ ! -s rolling-tasks ]; then
        echo '> no more rolling tasks, yay work done.'
        break;
    fi

    cat rolling-tasks | awk '/increase-capacity/{print $1" --desired-capacity "$3}' | xargs -r -L1 -P4 -t as-update-auto-scaling-group

    cat rolling-tasks | awk '/terminate-instance/{print $3" --no-decrement-desired-capacity --force"}' | xargs -r -L1 -P4 -t as-terminate-instance-in-auto-scaling-group

    echo '> sleep 2 min...'
    sleep 120s;

done