Creating a Lambda function in AWS - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to specify the runtime environment for the Lambda function.

AWS

lambda_function = aws.lambda_.Function("MyFunction",
    runtime=aws.lambda_.Runtime.[1],
    handler="index.handler",
    code=aws.lambda_.Code.from_asset("./app")
)

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

ANODEJS_14_X

BPYTHON_3_8

CJAVA_11

DGO_1_X

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing a runtime that does not match the code language.

Using an outdated or unsupported runtime.

The runtime specifies the language environment for the Lambda function. Here, NODEJS_14_X is a valid and common runtime.

2fill in blank

medium

Complete the code to set the Lambda function's handler correctly.

AWS

lambda_function = aws.lambda_.Function("MyFunction",
    runtime=aws.lambda_.Runtime.NODEJS_14_X,
    handler="[1]",
    code=aws.lambda_.Code.from_asset("./app")
)

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

Amain.handler

Bapp.main

Chandler.index

Dindex.handler

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping the order of file and function names.

Using a handler name that does not exist in the code.

The handler is the entry point for the Lambda function. It usually follows the format 'file.method'. Here, 'index.handler' means the handler function inside index.js.

3fill in blank

hard

Fix the error in the code by choosing the correct method to load the Lambda function code from a local folder.

AWS

lambda_function = aws.lambda_.Function("MyFunction",
    runtime=aws.lambda_.Runtime.NODEJS_14_X,
    handler="index.handler",
    code=aws.lambda_.Code.[1]("./app")
)

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

Afrom_file

Bfrom_directory

Cfrom_asset

Dfrom_path

Attempts:

3 left

💡 Hint

Common Mistakes

Using non-existent methods like from_file or from_path.

Confusing with other AWS SDK methods.

The correct method to load code from a local folder is 'from_asset'. Other options are invalid and cause errors.

4fill in blank

hard

Fill both blanks to add environment variables to the Lambda function.

AWS

lambda_function = aws.lambda_.Function("MyFunction",
    runtime=aws.lambda_.Runtime.NODEJS_14_X,
    handler="index.handler",
    code=aws.lambda_.Code.from_asset("./app"),
    environment={
        [1],
        [2]
    }
)

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

A"STAGE": "prod"

B"ENV": "dev"

C"DEBUG": "true"

D"VERSION": "1.0"

Attempts:

3 left

💡 Hint

Common Mistakes

Passing environment variables as strings instead of dictionaries.

Using invalid JSON syntax.

The environment property expects a dictionary of key-value pairs. Here, "ENV": "dev" and "DEBUG": "true" are valid key-value pairs.

5fill in blank

hard

Fill all three blanks to create a Lambda function with a timeout, memory size, and description.

AWS

lambda_function = aws.lambda_.Function("MyFunction",
    runtime=aws.lambda_.Runtime.NODEJS_14_X,
    handler="index.handler",
    code=aws.lambda_.Code.from_asset("./app"),
    timeout=[1],
    memory_size=[2],
    description=[3]
)

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

ADuration.seconds(10)

B128

C"My Lambda function for processing"

DDuration.minutes(5)

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect Duration methods or units.

Setting memory size as string instead of number.

Omitting quotes around description string.

The timeout should be set using Duration.minutes(5) for 5 minutes. Memory size is an integer like 128 MB. Description is a string describing the function.

Practice

1. What is the main purpose of an AWS Lambda function?

easy

A. To run code without managing servers

B. To store large amounts of data

C. To create virtual machines

D. To manage user permissions

Solution

1. Step 1: Understand Lambda's role

   AWS Lambda lets you run code without needing to manage servers or infrastructure.

2. Step 2: Compare options

   The incorrect options describe other AWS services such as user permissions (IAM), data storage (S3), and virtual machines (EC2).

3. Final Answer:

   To run code without managing servers -> Option A

4. Quick Check:

   Lambda = serverless code execution [OK]

Hint: Lambda runs code without servers [OK]

Common Mistakes:

• Confusing Lambda with storage services
• Thinking Lambda manages servers
• Mixing Lambda with user management

2. Which of the following is the correct way to specify the handler when creating a Lambda function in AWS?

easy

A. handler.index

B. index.handler

C. lambda.handler

D. handler.lambda

Solution

1. Step 1: Understand handler format

   The handler is specified as filename.functionname. Commonly, the file is index and function is handler.

2. Step 2: Match options

   Only index.handler matches the correct format; others reverse or misuse parts.

3. Final Answer:

   index.handler -> Option B

4. Quick Check:

   Handler = filename.function [OK]

Hint: Handler format is filename.functionname [OK]

Common Mistakes:

• Swapping filename and function name
• Using invalid handler names
• Confusing handler with runtime

3. Given this AWS Lambda function code snippet in Python:

def handler(event, context):
    return event.get('key', 'default')

What will be the output if the event is {}?

medium

A. "default"

B. None

C. Error

D. "key"

Solution

1. Step 1: Analyze the handler function

   The function returns the value of 'key' from event, or 'default' if 'key' is missing.

2. Step 2: Check the event input

   The event is an empty dictionary, so 'key' is not present, so it returns 'default'.

3. Final Answer:

   "default" -> Option A

4. Quick Check:

   Missing key returns default [OK]

Hint: Missing dict key returns default value [OK]

Common Mistakes:

• Assuming missing key returns None
• Expecting an error on missing key
• Confusing key name with value

4. You created a Lambda function but it fails with a permissions error when invoked. What is the most likely cause?

medium

A. The deployment package is too large

B. The handler name is incorrect

C. The runtime is not supported

D. The Lambda execution role lacks necessary permissions

Solution

1. Step 1: Understand permissions in Lambda

   Lambda functions need an IAM role with permissions to run and access resources.

2. Step 2: Identify cause of permissions error

   A permissions error usually means the execution role is missing required permissions.

3. Final Answer:

   The Lambda execution role lacks necessary permissions -> Option D

4. Quick Check:

   Permissions error = missing IAM role rights [OK]

Hint: Check IAM role permissions for Lambda [OK]

Common Mistakes:

• Blaming handler name for permissions error
• Ignoring IAM role setup
• Assuming runtime causes permissions error

5. You want to create a Lambda function that processes images uploaded to an S3 bucket. Which combination of settings is required to ensure the Lambda runs automatically when a new image is uploaded?

hard

A. Set Lambda runtime to Node.js and upload images directly to Lambda

B. Manually invoke Lambda after uploading images to S3

C. Set S3 event trigger on bucket for 'ObjectCreated' and assign Lambda execution role with S3 read permissions

D. Create an EC2 instance to monitor S3 and call Lambda

Solution

1. Step 1: Configure S3 event trigger

   To run Lambda automatically on uploads, configure S3 to trigger Lambda on 'ObjectCreated' events.

2. Step 2: Assign correct IAM role permissions

   Lambda needs an execution role with permissions to read from S3 to process images.

3. Final Answer:

   Set S3 event trigger on bucket for 'ObjectCreated' and assign Lambda execution role with S3 read permissions -> Option C

4. Quick Check:

   S3 trigger + IAM role = automatic Lambda run [OK]

Hint: Use S3 event triggers with proper IAM role [OK]

Common Mistakes:

• Thinking manual invocation is automatic
• Confusing runtime with event triggers
• Using EC2 unnecessarily for Lambda triggers