Is running Fargate and API Gateway without a load balancer in the production environment a bad idea?

No, AWS API Gateway does not automatically spread traffic across multiple Fargate tasks. It only routes traffic to one target. To distribute traffic across multiple tasks, you need to use a load balancer, such as an Application Load Balancer or a Network Load Balancer, in front of the tasks.

Running Fargate and API Gateway without a load balancer in a production environment can have potential drawbacks and risks. Without a load balancer, your service may not have automatic failover, scaling, or management of incoming traffic. It can also increase the risk of downtime and decreased performance during traffic spikes. It is recommended to use a load balancer in a production environment to ensure high availability, scalability, and to offload the management of incoming traffic.