ECS with ALB integration in AWS - Step-by-Step Execution

Process Flow - ECS with ALB integration

Create ECS Cluster

↓

Define Task with Container

↓

Create ALB (Application Load Balancer)

↓

Create Target Group for ALB

↓

Configure ALB Listener to Forward to Target Group

↓

Create ECS Service with ALB Integration

↓

ECS Service Registers Tasks to Target Group

↓

ALB Routes Incoming Traffic to ECS Tasks

↓

Users Access Service via ALB

This flow shows how ECS tasks are connected to an Application Load Balancer to route user traffic to running containers.

Execution Sample

AWS

1. Create ECS Cluster
2. Define Task with container image and port
3. Create ALB and Target Group
4. Set ALB Listener to forward to Target Group
5. Create ECS Service linked to ALB Target Group

This sequence sets up ECS with ALB to route traffic to container tasks.

Process Table

Step	Action	Resource Created/Updated	State Change	Result
1	Create ECS Cluster	ECS Cluster	Cluster active	Ready to run tasks
2	Define Task Definition	Task Definition	Task registered	Container image and port set
3	Create ALB	Application Load Balancer	ALB active	Listening for traffic
4	Create Target Group	Target Group	Target group active	Ready to register targets
5	Configure ALB Listener	ALB Listener	Listener active	Forwards to Target Group
6	Create ECS Service with ALB integration	ECS Service	Service active	Tasks launched and registered to Target Group
7	Tasks register to Target Group	Target Group	Targets healthy	Ready to receive traffic
8	ALB routes traffic	ALB	Traffic forwarded	Users access containers via ALB
9	Exit	N/A	N/A	Setup complete, service accessible

💡 All resources created and ECS tasks registered to ALB target group; traffic routing active

Status Tracker

Resource	Initial	After Creation	After Configuration	Final State
ECS Cluster	None	Created	Active	Active
Task Definition	None	Defined	Registered	Registered
ALB	None	Created	Listener Configured	Active with Listener
Target Group	None	Created	Targets Registered	Healthy Targets
ECS Service	None	Created	Tasks Running	Active with Tasks
Tasks	None	Launched	Registered to Target Group	Healthy and Serving

Key Moments - 3 Insights

Why do ECS tasks need to register with the ALB target group?

Because the ALB uses the target group to know where to send incoming traffic. Without registration, the ALB cannot route requests to the running containers. See execution_table step 7.

What happens if the ALB listener is not configured to forward to the target group?

The ALB will not know where to send traffic, so requests will fail. Listener configuration is essential to connect ALB to ECS tasks. See execution_table step 5.

Can ECS tasks run without an ALB?

Yes, but without an ALB, you must manage task IPs and ports manually. ALB simplifies routing and load balancing. This is why ALB integration is common. See overall concept_flow.

Visual Quiz - 3 Questions

Look at the execution_table at step 6. What is the state of the ECS Service after creation?

A Service active with tasks launched and registered

B Service created but no tasks running

C Service inactive

D Service deleted

💡 Hint

Refer to execution_table row with Step 6 under 'State Change' and 'Result'

At which step does the ALB start forwarding traffic to ECS tasks?

A Step 4

B Step 8

C Step 5

D Step 2

💡 Hint

Check execution_table for when traffic forwarding is active

If the target group is not healthy, what will happen to user traffic?

A Traffic will be routed normally

B ALB will create new tasks automatically

C Traffic will fail to reach ECS tasks

D ECS service will stop

💡 Hint

See variable_tracker row for Target Group final state and execution_table step 7

Concept Snapshot

ECS with ALB integration:
- Create ECS Cluster and Task Definition
- Create ALB and Target Group
- Configure ALB Listener to forward to Target Group
- Create ECS Service linked to ALB Target Group
- ECS tasks register to Target Group
- ALB routes user traffic to running containers

Full Transcript

This visual execution shows how to connect AWS ECS with an Application Load Balancer (ALB). First, an ECS cluster is created to run containers. Then, a task definition specifies the container image and port. An ALB is created to handle incoming traffic. A target group is made for the ALB to send traffic to ECS tasks. The ALB listener is configured to forward requests to this target group. An ECS service is created that launches tasks and registers them with the target group. Once tasks are healthy and registered, the ALB routes user traffic to these containers. This setup allows users to access containerized applications through the ALB, which balances load and manages traffic routing automatically.