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Deploying Docker Containers on AWS ECS Fargate

This documentation provides a step-by-step guide on how to create a task definition, service, attach it to an Application Load Balancer (ALB) in order publish it to the internet.

Table of Contents​

  1. Prerequisites
  2. Create a Task Definition
  3. Create an ECS Service
  4. Fix Your Health Checks
  5. Check Your Application

Overview​

Here is a diagram explaining the architecture we will be following:

You can see our docker containers are pulled into AWS through the task definition and turned into a service. For the users to reach our services, we need to simply add a new target group to our existing load balancer.

Prerequisites​

Before proceeding with these steps, make sure you have the following:

  • An AWS account with necessary permissions to create ECS resources, add target groups, and modify load balancers.
  • Have created a docker container from our previous guide, and have it published on DockerHub.

Create a Task Definition​

  1. In AWS, Navigate to Amazon Elastic Container Service > Task definition > Create new task definition
  2. Task name: choose something descriptive like: metadata-api-task or population-dash-task
  3. Container: Create a container definition
    1. Container name: ex. metadata-api-container
    2. Image URI: your DockerHub image URI ex. gbadsinformatics/meta-api:latest
    3. Port mapping: add your exposed ports here, ex. TCP on port 80 (http)\ Make sure you use http; our load balancer will add https later for you.
    4. Environment Variables: these are the variables referenced in docker containers. For dashboards, we use DASH_BASE_URL to set the URL path for the dashboard like /dashboards/population. These variables need to be referenced in your code. It will not automatically work. Other applications we have use environment variables to pass in secret credentials.
  4. Configure environment: resources
    1. Change the resources: Usually each container we set to 1 vCPU and 2 GiB of memory
    2. Task role: set to ecsTaskExecutionRole
    3. Keep storage and logging as default
  5. Finally review & create your task definition.

Create an ECS Service​

  1. Go back to the cluster and click create a new service.
  2. Deployment Configuration:
    1. Make sure you have a service selected.
    2. Select Family and choose your new task definition.
    3. Service name: ex metadata-api-service
  3. Networking:
    1. Make sure the default VPC is selected, and all 3 subnets are selected.
    2. Choose security group
      • remove default
      • add GBADs-Dashboard-LB-SecurityGroup (Despite the name, this is used for all containers, not just dashboards)
  4. Load Balancing:
    1. Select Use an existing load balancer
    2. Choose Dashboards-ALB (This is used for all containers, not just dashboards)
    3. Select Use an existing listener
    4. Choose 443: HTTPS - This is where https is added for you
    5. Select Create a new target group
    6. Target group name: something like metadata-api-target-group
    7. Path pattern: Change this to your applications base URL but add a '*'. \ Ex /dashboards/population*, this forwards all traffic with this pattern to our new container.
    8. Evaluation order: scroll through the existing rules and select the next number in order.\ Sometimes we have applications with overlapping patterns like /dashboards/population and /dashboards/population-v2. It is important here that the longest URL gets prioritized in the evaluation order (longer URL needs a lower number). You may need to shift around some rules to make space.
    9. Health Check Path: this path is used to check the status of your application. This usually is the base URL of your application, or the docs site of an API. Like /dashboards/population or /api/docs
    10. Click create.

Fix Your Health Checks​

Before checking your service, we need to make a change to our new target group to accept more HTTP return codes.

  1. Go to EC2 > Target Groups > your-new-target-group > Health Checks > Edit
  2. Open Advanced health check settings
  3. Change success codes to 200-399
  4. Save changes

Check Your Application​

You can now go to www.gbadske.org/[your base URL here] like, www.gbadske.org/dashboards/population to check your application status.