AWS Lambda: Create a Function from CLI

Creating Lambda Functions from the CLI

The aws lambda create-function command deploys a new Lambda function with a specified runtime, handler, IAM role, and code package.

Basic Function Creation

aws lambda create-function \
  --function-name my-api-handler \
  --runtime nodejs20.x \
  --handler index.handler \
  --role arn:aws:iam::123456789012:role/lambda-exec-role \
  --zip-file fileb://function.zip

Note: Use fileb:// (binary file) for zip archives, not file:// (text file).

With Memory and Timeout

aws lambda create-function \
  --function-name data-processor \
  --runtime python3.12 \
  --handler app.lambda_handler \
  --role arn:aws:iam::123456789012:role/lambda-exec-role \
  --zip-file fileb://deployment.zip \
  --timeout 300 \
  --memory-size 512

Key Parameters

Flag	Default	Range	Notes
--timeout	3 seconds	1-900	Maximum execution time
--memory-size	128 MB	128-10240	Also scales CPU proportionally
--runtime	—	See list	nodejs20.x, python3.12, java21, etc.
--handler	—	—	Entry point: filename.function_name

With Environment Variables

aws lambda create-function \
  --function-name my-function \
  --runtime python3.12 \
  --handler app.handler \
  --role arn:aws:iam::123456789012:role/lambda-role \
  --zip-file fileb://function.zip \
  --environment "Variables={DB_HOST=mydb.cluster.rds.amazonaws.com,LOG_LEVEL=info}"

With VPC Configuration

aws lambda create-function \
  --function-name vpc-function \
  --runtime nodejs20.x \
  --handler index.handler \
  --role arn:aws:iam::123456789012:role/lambda-vpc-role \
  --zip-file fileb://function.zip \
  --vpc-config SubnetIds=subnet-abc123,subnet-def456,SecurityGroupIds=sg-abc123

Deployment Workflow

1. Write your function code
2. Create the IAM execution role with necessary permissions
3. Package the code: zip -r function.zip .
4. Run create-function
5. Test with aws lambda invoke