ECS Flashcards
What is AWS ECS?
“A container managment service that uses Docker containers on a cluster
set up regionally”
What is a image?
“A runable snapshot of an application and it’s environment
A container is made by running an image
point in time capture of code and dependencies”
What is a Dockerfile?
“A static read-only file with executable code containing
system libraries
system tools
other platform settings a software program needs to run on a containerization platform
Images are typically built from a Dockerfile but not exclusivly
A Dockerfile is built to make an image”
What is a Task?
“The instantiation of a task definition within a cluster
You can specify the number of tasks that will fun on your cluster”
What is a task definition?
“A JSON file that defines how to launch a Docker container on an instance(metadata for container)
ref to Image
Environment Variables
Links to other containers
Volume
up to a maximum or ten that form your application
point in time capture of configuration for running an image”
What is the service scheduling feature?
“A feature on the service description level
provides options specifying how or when a task should be placed into a cluster”
What is a Cluster?
A grouping EC2 instances that each run Docker and a Container agent(provided by ECS)
What are the launch types?
“An ECS level setting determining the type of infrastructure on which your tasks and services are hosted
EC2 - instances that you manage
Can use 3rd party security configuration
Can use isolation frameworks
Fargate - a serverless option for Container services”
What is a Container agent?
“A component that runs on each infrastructure resource (Container EC2 instance) within a cluster
It sends information about the resources current running task and resource utilization to the ECS
Container agents are responsible for starting and stopping tasks when requested by the ECS”
Clusters and AZs
Clusters are an EC2 group designation and can span across multiple AZs
EC2 instances accessing ECS service endpoints
“Either:
Create an interface VPC Endpoint for ECS service and attach to VPC subnets route table in which ECS instances are running
or
Create a NAT Gatewat and attach it to VPC subnet’s route table in which ECS insances are running”
What are the parameters specified in task definition?
“The Docker images to use with the container in the task
How much CPU and memory to use with each container
The command the container should run when it is started
launch type
whether containers are linked in a task
data volumes that should be used with the containers in the task
Docker networking mode
(optional)
Environment variables - IAM role - ports”
What is a Service Definition?
“Defines which task definition to use with your service
how many instantiations of that task to run
which load balancers(if any) to associate with your class”
What are common parameters for Service Definitions?
“Cluster on which to run your service
Full ARN of the task definition to run in your service
IAM role that allows ECS to make calls to your load balancer on your behalf”
What is the user data feature?
“Convenience feature for ECS instances that allows perform common automated configuration tasks and even run scripts when the instance boots. eliminating the need to SSH into the instance to set up the Docker Daemon or Container Agent”
