AWS-ECS

🔴 ECS ==> 
    It's a managed container orchestration service offered by Amazon Web Services (AWS) that helps you deploy, run, and scale containerized applications.
    ECS automates the deployment, scaling, and management of containerized applications across a cluster of EC2 instances or AWS Fargate.

🔴 Core Components ==>

    🔘ECS Cluster ==> 
      The central unit that groups resources and orchestrates container tasks. It doesn't directly run containers but manages their deployment, scaling, and networking.

      Optional Compute Resources:
       o EC2 Instances: You can configure your cluster to use EC2 instances as compute resources to run container tasks. ECS can launch and manage these 
         instances, or you can bring your own existing EC2 instances into the cluster.
       o AWS Fargate: A serverless compute engine for containers. With Fargate, ECS provisions, scales, and manages the underlying compute resources, 
         eliminating the need to manage EC2 instances yourself.

    🔘Task Definition ==> 
      A blueprint that defines how container tasks should be run. It includes details like:
      Container Image: The Docker image to be used for the task.
      CPU and Memory Requirements: Hardware resource allocation for the container.
      Environment Variables: Key-value pairs to configure the container environment.
      Ports: Network ports exposed by the container.
      Volumes: Data volumes to be mounted with the container.
      Security Considerations: Security policies applied to the container.

    🔘Task ==> 
      A single execution of a task definition. It represents a running instance of your containerized application. Tasks have a lifecycle that can be running, 
      pending, or stopped. ECS manages the lifecycle of tasks, ensuring they are healthy and restarting them if they fail.

    🔘Service ==>
      A persistent entity that represents the desired state for your application. It references a task definition and specifies:
      Desired Task Count: The number of tasks you want to run concurrently for your application.
      Scheduling and Placement Strategies: How tasks are scheduled and placed on compute resources within the cluster.
      Load Balancing: Integration with load balancers to distribute traffic across healthy tasks.
      Service Discovery: Mechanisms for tasks to discover and communicate with each other.
      Auto Scaling: Rules to automatically scale the number of tasks up or down


   🔘ECS Agent ==> 
      A software agent that runs on each EC2 instance in an ECS cluster. It communicates with the ECS service to receive task definitions, download container images, 
      and start and manage container tasks on the instance. (Not applicable to Fargate)

🔴 How They Work Together:

    You create a task definition that specifies your container image and configuration.
    You create a service that references the task definition and defines the desired number of tasks to run concurrently.
    You deploy the service to an ECS cluster.
    The ECS service makes requests to the ECS cluster.
    The ECS cluster interacts with the ECS agents running on EC2 instances (if applicable) or provisions resources on Fargate.
    ECS agents or Fargate pull the container image from the container registry (e.g., Amazon ECR) and start running container tasks based on the task definition.
    ECS manages the lifecycle of tasks, ensuring they are healthy, restarting them if they fail, and scaling the service up or down based on your service definition.