Services and tasks in AWS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create an AWS S3 bucket using AWS CLI.

AWS

aws s3api create-bucket --bucket [1] --region us-east-1

Drag options to blanks, or click blank then click option'

Acreate-bucket

Bmy-unique-bucket-123

Clist-buckets

Ddelete-bucket

Attempts:

3 left

💡 Hint

Common Mistakes

Using AWS CLI commands like 'list-buckets' instead of a bucket name.

Leaving the bucket name blank.

The --bucket option requires the name of the bucket you want to create.

2fill in blank

medium

Complete the code to start an EC2 instance using AWS CLI.

AWS

aws ec2 start-instances --instance-ids [1]

Drag options to blanks, or click blank then click option'

Ai-1234567890abcdef0

Bstart-instances

Cdescribe-instances

Dstop-instances

Attempts:

3 left

💡 Hint

Common Mistakes

Using command names instead of instance IDs.

Using incorrect instance ID formats.

The --instance-ids option requires the ID of the EC2 instance to start.

3fill in blank

hard

Fix the error in the AWS CLI command to list all running EC2 instances.

AWS

aws ec2 describe-instances --filters Name=instance-state-name,Values=[1]

Drag options to blanks, or click blank then click option'

Astopped

Bterminated

Cpending

Drunning

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'stopped' or 'terminated' which show inactive instances.

Using 'pending' which shows instances starting but not yet running.

The filter value running lists all EC2 instances that are currently running.

4fill in blank

hard

Fill both blanks to create a security group rule allowing inbound HTTP traffic on port 80.

AWS

aws ec2 authorize-security-group-ingress --group-id [1] --protocol [2] --port 80 --cidr 0.0.0.0/0

Drag options to blanks, or click blank then click option'

Asg-0a1b2c3d4e5f6g7h8

Bsg-1234567890abcdef0

Ctcp

Dudp

Attempts:

3 left

💡 Hint

Common Mistakes

Using UDP protocol instead of TCP for HTTP.

Using incorrect security group IDs.

The --group-id specifies the security group ID, and --protocol should be 'tcp' for HTTP traffic.

5fill in blank

hard

Fill all three blanks to create an IAM user, attach a policy, and add the user to a group.

AWS

aws iam create-user --user-name [1]
aws iam attach-user-policy --user-name [2] --policy-arn [3]
aws iam add-user-to-group --user-name [2] --group-name Developers

Drag options to blanks, or click blank then click option'

Anewuser

Carn:aws:iam::aws:policy/AmazonS3ReadOnlyAccess

Darn:aws:iam::aws:policy/AdministratorAccess

Attempts:

3 left

💡 Hint

Common Mistakes

Using different user names in commands.

Attaching the wrong policy ARN.

The user name must be consistent across commands, and the policy ARN specifies the permissions to attach.

Practice

1. What is the main role of a service in AWS when managing your app tasks?

easy

A. To define the resources and containers for the app

B. To keep the app tasks running and replace them if they fail

C. To store data for the app

D. To monitor network traffic

Solution

1. Step 1: Understand what a service does

   A service manages running copies of your app tasks and ensures they stay running.

2. Step 2: Compare with other options

   Defining resources and containers is the task's role, not the service's. Storing data and monitoring traffic are unrelated.

3. Final Answer:

   To keep the app tasks running and replace them if they fail -> Option B

4. Quick Check:

   Service manages tasks = B [OK]

Hint: Services keep tasks running and replace failed ones [OK]

Common Mistakes:

• Confusing service with task definition
• Thinking service stores data
• Assuming service monitors network

2. Which of the following is the correct way to define a task in AWS ECS?

easy

A. A database schema for app data

B. A YAML file listing EC2 instances

C. A JSON file specifying containers, CPU, and memory

D. A script to launch EC2 instances

Solution

1. Step 1: Identify task definition format

   A task in AWS ECS is defined by a JSON file that specifies containers, CPU, and memory requirements.

2. Step 2: Eliminate incorrect options

   YAML listing EC2 instances is not a task definition. Scripts to launch EC2 or database schemas are unrelated.

3. Final Answer:

   A JSON file specifying containers, CPU, and memory -> Option C

4. Quick Check:

   Task definition = JSON file with containers [OK]

Hint: Task definitions use JSON to specify containers and resources [OK]

Common Mistakes:

• Confusing task definition with instance listing
• Using scripts instead of JSON for tasks
• Mixing database schemas with task definitions

3. If you create a service with a desired count of 3 tasks, but one task fails, what will AWS ECS do?

medium

A. Replace the failed task to maintain 3 running tasks

B. Stop all tasks and alert the user

C. Ignore the failure and keep 2 tasks running

D. Scale down the service to 2 tasks

Solution

1. Step 1: Understand service desired count behavior

   The service tries to keep the number of running tasks equal to the desired count.

2. Step 2: What happens on task failure?

   If a task fails, the service replaces it to maintain the desired count of 3 tasks.

3. Final Answer:

   Replace the failed task to maintain 3 running tasks -> Option A

4. Quick Check:

   Service maintains desired count = A [OK]

Hint: Service replaces failed tasks to keep desired count [OK]

Common Mistakes:

• Thinking service stops all tasks on failure
• Assuming service ignores failures
• Believing service scales down automatically

4. You defined a task with 512 MB memory but your service fails to start tasks due to insufficient resources. What is the likely problem?

medium

A. The container image is missing

B. The task definition JSON is invalid

C. The service desired count is set to zero

D. The cluster has no available memory to run the task

Solution

1. Step 1: Analyze the error cause

   Insufficient resources usually mean the cluster lacks enough memory to run the task.

2. Step 2: Check other options

   Invalid JSON or zero desired count would cause different errors. Missing image causes container start failure, not resource error.

3. Final Answer:

   The cluster has no available memory to run the task -> Option D

4. Quick Check:

   Insufficient resources = cluster memory shortage [OK]

Hint: Check cluster memory before blaming task definition [OK]

Common Mistakes:

• Assuming JSON syntax error causes resource failure
• Ignoring cluster resource limits
• Confusing desired count zero with resource shortage

5. You want to run a web app that scales automatically based on CPU usage. Which combination should you use in AWS ECS?

hard

A. Create a service with a task definition and enable auto scaling on the service

B. Create only tasks without a service and manually start more tasks

C. Use EC2 instances without ECS to run containers

D. Create a service but disable task definitions

Solution

1. Step 1: Identify components for scaling

   A service manages tasks and can be configured with auto scaling based on CPU.

2. Step 2: Evaluate other options

   Running tasks without a service lacks auto scaling. Using EC2 alone misses ECS benefits. Disabling task definitions is invalid.

3. Final Answer:

   Create a service with a task definition and enable auto scaling on the service -> Option A

4. Quick Check:

   Service + task + auto scaling = C [OK]

Hint: Use service with auto scaling for CPU-based scaling [OK]

Common Mistakes:

• Skipping service and expecting auto scaling
• Confusing EC2 usage without ECS
• Disabling task definitions breaks deployment