There is an ongoing outage on the primary CPAN mirror. It is possible to work around the issue by using MetaCPAN as a mirror.

 / 
App-FargateStack-1.0.50
/ App::ApplicationAutoscaling 
aws application-autoscaling register-scalable-target \
  --service-namespace ecs \
  --scalable-dimension ecs:service:DesiredCount \
  --resource-id service/YOUR_CLUSTER_NAME/YOUR_SERVICE_NAME \
  --min-capacity 1 \
  --max-capacity 10


aws application-autoscaling put-scaling-policy \
  --policy-name "alb-requests-per-minute-policy" \
  --service-namespace ecs \
  --scalable-dimension ecs:service:DesiredCount \
  --resource-id service/YOUR_CLUSTER_NAME/YOUR_SERVICE_NAME \
  --policy-type TargetTrackingScaling \
  --target-tracking-scaling-policy-configuration '{
      "TargetValue": 500.0,
      "PredefinedMetricSpecification": {
        "PredefinedMetricType": "ALBRequestCountPerTarget",
        "ResourceLabel": "YOUR_ALB_AND_TARGET_GROUP_LABEL"
      },
      "ScaleOutCooldown": 60,
      "ScaleInCooldown": 300
    }'