# Fargate services (always on)

> A container that runs all the time behind a load balancer. Where a Lambda goes once it's busy all day.

- Verdict: Use when it fits
- Vendor: AWS
- Layer: [Compute](https://cloudlesslabs.com/stack/layers/compute/index.md). Job: Steady HTTP core
- Last reviewed: 25 October 2026, by Nicolas Dao (Cloudless Labs, Sydney)
- Web page: https://cloudlesslabs.com/stack/aws-fargate-service/. The whole stack in one file: https://cloudlesslabs.com/stack/brief.md

Lambda is my default, and a Fargate service is where a Lambda goes when it has stopped being spiky. The signal isn't a high reserved concurrency, which costs nothing. It's concurrency that stays high all day: an API that waits on Postgres pays Lambda for every millisecond of that wait, request by request, while one container serves many of them at once.

The numbers are in [Lambda, Fargate or EC2?](https://cloudlesslabs.com/stack/guides/lambda-or-containers/index.md): at 50 requests in flight all day, about $1,883 a month on Lambda against about $437 on Fargate. At 5, the saving doesn't pay for the container. So I move only the steady HTTP core, measured first, and keep events, queues, schedules and spikes on Lambda.

How I'd wire it: ECS Express Mode on Fargate, Arm, one Node.js service, the domain on a Worker or CloudFront in front so the move is an origin change, and a Compute Savings Plan once three months show the floor.

## Use it when

- One HTTP function's concurrency stays at about 10 or more all night, or averages 30% of its daily peak, and its Lambda bill passes about $500 a month.
- The service mostly waits on Postgres or other APIs: one Node.js process serves many requests at once, where Lambda bills each one for its whole wait.
- A hard Lambda limit hits: requests over 15 minutes, long-lived connections, more than 10 GB of memory, or Postgres running out of connections.

## Don't use it when

- Traffic is spiky, with a daily average a tenth of its peak or less: Lambda scales in seconds and costs nothing in between. Sized for a ten-minute peak, a container runs it all day.
- Events, queues and schedules: they stay on Lambda (or a Fargate scheduled task for long jobs).
- The saving would be under about $300 a month: it doesn't pay for owning a load balancer, scaling and deploys.

## Pricing

Per second of vCPU and memory, around the clock. Sydney, Arm: $0.03885 per vCPU-hour and $0.00426 per GB-hour (x86: $0.04856 and $0.00532). A 1 vCPU / 2 GB Arm task is about $34.58 a month. Add the Application Load Balancer ($18.40 a month plus about $5.84 per capacity unit) and $3.65 a month per public IPv4 address: the smallest highly available setup, two small tasks in two zones, is about $73 a month. Compute Savings Plans take 21% (1 year) to 46% (3 years) off Fargate on Arm.

## Gotchas, with fixes

- **Gotcha:** Target-tracking scaling reacts on one-minute metrics with a cooldown, then new tasks must start: a sudden ten-minute peak is mostly over before the capacity arrives.
  **Fix:** Keep the spiky part on Lambda, or use scheduled scaling when the peak's time is known.
- **Gotcha:** Tasks in private subnets need a NAT gateway to reach ECR, Neon or any API: about $43 a month before data, for every zone.
  **Fix:** Run tasks in public subnets with public IPs and a security group that only accepts the load balancer, or add VPC endpoints when they must stay private.
- **Gotcha:** App Runner, the easy way to run a container service, is closed to new customers.
  **Fix:** Use ECS Express Mode: one call creates the Fargate service, the load balancer with TLS, health checks and scaling, at no extra charge.

## Provisioning

Official Pulumi package · Official Terraform provider

aws.ecs.Service, TaskDefinition and an Application Load Balancer in @pulumi/aws (awsx.ecs.FargateService wraps them). ECS Express Mode creates all of it in one call; its Terraform support is official.

## Instead, consider

- [AWS Lambda](https://cloudlesslabs.com/stack/aws-lambda/index.md): Spiky traffic, events, queues, schedules and CPU-heavy work.
- [Lambda Managed Instances](https://cloudlesslabs.com/stack/aws-lambda-managed-instances/index.md): A steady function you want to keep as a Lambda.
- [EC2](https://cloudlesslabs.com/stack/aws-ec2/index.md): GPUs, special instance types or local disks.
- [Fargate scheduled tasks](https://cloudlesslabs.com/stack/aws-fargate-scheduled-tasks/index.md): A long job that runs on a schedule, not a service that answers all day.

## Worked examples

- [Lambda, Fargate or EC2?](https://cloudlesslabs.com/stack/guides/lambda-or-containers/index.md): My Lambda is busy all day, or its reserved concurrency keeps going up. When is it time to move to a container, and where is the line?

## Sources

- [Fargate pricing](https://aws.amazon.com/fargate/pricing/)
- [Elastic Load Balancing pricing](https://aws.amazon.com/elasticloadbalancing/pricing/)
- [ECS Express Mode](https://docs.aws.amazon.com/AmazonECS/latest/developerguide/express-service-overview.html)
- [App Runner availability change](https://docs.aws.amazon.com/apprunner/latest/dg/apprunner-availability-change.html)

## Related

- [Compute](https://cloudlesslabs.com/stack/layers/compute/index.md): every tool in this layer, with its verdict
- [The whole stack in one file](https://cloudlesslabs.com/stack/brief.md): every use case and tool, for questions that span many
- [Map of every Markdown file on cloudlesslabs.com, with what each one answers](https://ask.cloudlesslabs.com)