Examples

These examples demonstrate practical, real-world usage patterns for the lambda-function module. Each example is self-contained and ready to run—simply copy the configuration, customize the values for your environment, and apply.

Getting Started

To run any example, follow these steps:

  1. Authenticate with the registry: terraform login registry.patterneddesigns.ca
  2. Initialize the working directory: terraform init
  3. Review the execution plan: terraform plan
  4. Apply the configuration: terraform apply

Usage Examples

Basic Usage

Minimal configuration for a Python Lambda function

module "basic_function" {
  source  = "registry.patterneddesigns.ca/patterneddesigns/lambda-function/aws"
  version = "3.1.0"

  function_name = "hello-world"
  runtime       = "python3.12"
  handler       = "main.handler"
  source_path   = "./src"
}

API Handler

Lambda function optimized for API Gateway integration

module "api_handler" {
  source  = "registry.patterneddesigns.ca/patterneddesigns/lambda-function/aws"
  version = "3.1.0"

  function_name = "api-handler"
  runtime       = "nodejs20.x"
  handler       = "index.handler"
  source_path   = "./dist"

  memory_size = 256
  timeout     = 29  # API Gateway limit

  environment_variables = {
    NODE_ENV     = "production"
    API_VERSION  = "v1"
  }
}

# Grant API Gateway permission to invoke
resource "aws_lambda_permission" "api_gateway" {
  statement_id  = "AllowAPIGateway"
  action        = "lambda:InvokeFunction"
  function_name = module.api_handler.function_name
  principal     = "apigateway.amazonaws.com"
}

VPC-Connected Function

Function with access to private resources (RDS, ElastiCache)

data "aws_vpc" "main" {
  tags = { Name = "main" }
}

data "aws_subnets" "private" {
  filter {
    name   = "vpc-id"
    values = [data.aws_vpc.main.id]
  }
  tags = { Tier = "private" }
}

resource "aws_security_group" "lambda" {
  name_prefix = "lambda-"
  vpc_id      = data.aws_vpc.main.id

  egress {
    from_port   = 0
    to_port     = 0
    protocol    = "-1"
    cidr_blocks = ["0.0.0.0/0"]
  }
}

module "db_processor" {
  source  = "registry.patterneddesigns.ca/patterneddesigns/lambda-function/aws"
  version = "3.1.0"

  function_name = "db-processor"
  runtime       = "python3.12"
  handler       = "main.handler"
  source_path   = "./src"

  memory_size = 512
  timeout     = 300

  vpc_config = {
    subnet_ids         = data.aws_subnets.private.ids
    security_group_ids = [aws_security_group.lambda.id]
  }

  environment_variables = {
    DB_HOST = "db.internal.example.com"
    DB_NAME = "myapp"
  }
}

Event Processor

High-throughput event processing with concurrency controls

module "event_processor" {
  source  = "registry.patterneddesigns.ca/patterneddesigns/lambda-function/aws"
  version = "3.1.0"

  function_name = "event-processor"
  runtime       = "python3.12"
  handler       = "main.handler"
  source_path   = "./src"

  memory_size = 1024
  timeout     = 60

  # Limit concurrent executions to protect downstream services
  reserved_concurrent_executions = 50

  environment_variables = {
    BATCH_SIZE    = "100"
    MAX_RETRIES   = "3"
  }
}

# SQS trigger
resource "aws_lambda_event_source_mapping" "sqs" {
  event_source_arn = aws_sqs_queue.events.arn
  function_name    = module.event_processor.function_arn
  batch_size       = 10
}

Scheduled Function

CloudWatch Events scheduled execution

module "scheduled_task" {
  source  = "registry.patterneddesigns.ca/patterneddesigns/lambda-function/aws"
  version = "3.1.0"

  function_name = "daily-report"
  runtime       = "python3.12"
  handler       = "main.handler"
  source_path   = "./src"

  timeout = 900  # 15 minutes for long-running reports

  environment_variables = {
    REPORT_BUCKET = aws_s3_bucket.reports.id
  }
}

resource "aws_cloudwatch_event_rule" "daily" {
  name                = "daily-report"
  schedule_expression = "cron(0 6 * * ? *)"  # 6 AM UTC daily
}

resource "aws_cloudwatch_event_target" "lambda" {
  rule      = aws_cloudwatch_event_rule.daily.name
  target_id = "DailyReport"
  arn       = module.scheduled_task.function_arn
}

resource "aws_lambda_permission" "events" {
  statement_id  = "AllowCloudWatchEvents"
  action        = "lambda:InvokeFunction"
  function_name = module.scheduled_task.function_name
  principal     = "events.amazonaws.com"
  source_arn    = aws_cloudwatch_event_rule.daily.arn
}

Multiple Environments

Using the same module across environments

locals {
  environments = {
    dev = {
      memory_size = 128
      timeout     = 30
      log_level   = "DEBUG"
    }
    prod = {
      memory_size = 512
      timeout     = 60
      log_level   = "INFO"
    }
  }
}

module "api_function" {
  for_each = local.environments

  source  = "registry.patterneddesigns.ca/patterneddesigns/lambda-function/aws"
  version = "3.1.0"

  function_name = "api-handler-${each.key}"
  runtime       = "python3.12"
  handler       = "main.handler"
  source_path   = "./src"

  memory_size = each.value.memory_size
  timeout     = each.value.timeout

  environment_variables = {
    ENVIRONMENT = each.key
    LOG_LEVEL   = each.value.log_level
  }
}