16. Docker (ECS, ECR, Fargate)

Question 1

What is the ECS “binpack” strategy?

Answer 1

• ECS task placement strategy
• place tasks based on the least available amount of CPU or memory
• This minimizes the number of instance in use (cost savings)
• Tries to maximize EC2 instances in use

Question 2

What is the ECS “spread” strategy?

Answer 2

• place the task evenly based on the specified value

- Example: instanceId, attribute:ecs.availability-zone

Question 3

What is the ECS “distinctInstance” constraint?

Answer 3

• ECS task placement constraint

- place each task on a different container instance

Question 4

What is the ECS “memberOf” constraint?

Answer 4

• ECS task placement constraint
• places task on instances that satisfy an expression
• Uses the Cluster Query Language (advanced)
• Example: only place these types of tasks on t2 instances

Question 5

What is Fargate?

Answer 5

• Serverless ECS (serverless containers / docker)
• no more EC2 to provision!
• AWS provisions containers for us and assigns them ENI

Question 6

What are the 3 ECS “flavors”?

Answer 6

1. ECS Classic
2. Fargate
3. EKS

Question 7

What is an ECS Cluster?

Answer 7

Multiple EC2 instances which will house the docker containers

Question 8

What is an ECS Task Definition?

Answer 8

A JSON file that defines the configuration of (up to 10) containers you want to run

Question 9

What is an ECS Task?

Answer 9

Tasks launch containers defined in the Task Definition.

Tasks do not remain running once their workload is complete.

Question 10

What is an ECS Service?

Answer 10

A Service ensures tasks remain running (e.g. web-apps)

Question 11

What is an ECS Container Agent?

Answer 11

A binary installed on each EC2 instance which monitors, starts, and stops tasks

Question 12

If you want to run a service but it cannot have a cold start, what should you use?

Answer 12

You should use ECS.

Fargate and Lambda both have cold starts

Question 13

What is the maximum memory of a Fargate service?

Answer 13

30 GB

Question 14

What is the maximum memory of a Lambda service?

Answer 14

3GB

Question 15

What is the maximum duration of a Fargate service?

Answer 15

As long as you want

Question 16

What is the maximum duration of a Lambda service?

Answer 16

15 min

Question 17

True or False: You cannot apply an IAM role to a task in Fargate.

Answer 17

False

You CAN apply an IAM role to a task in Fargate (and ECS). You can also apply an IAM role to services.

Question 18

True or False: You can define multiple containers within a task definition.

Answer 18

True

Question 19

The (docker) IMAGES can be provided via where?

Answer 19

ECR or an official docker repository (e.g. Docker Hub)

Question 20

How many essential containers must you have in ECS?

Answer 20

You must have one essential container. If this container fails or stops then all other containers will be stopped.

Question 21

True or False: You cannot apply a Security Group to a task in Fargate.

Answer 21

False

You CAN apply a Security Group to a task in Fargate (and ECS). You can also apply a security group to services.

Question 22

What are the ECS task placement constraints?

Answer 22

distinctInstance and memberOf

Question 23

What are the ECS task placement strategies?

Answer 23

Binpack, Random, Spread