# Terraform Lambda Deployment

## Terraform Lambda Deployment

```hcl
# main.tf
terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
  }
}

provider "aws" {
  region = var.aws_region
}

# Lambda execution role
resource "aws_iam_role" "lambda_role" {
  name = "lambda-execution-role"

  assume_role_policy = jsonencode({
    Version = "2012-10-17"
    Statement = [{
      Action = "sts:AssumeRole"
      Effect = "Allow"
      Principal = {
        Service = "lambda.amazonaws.com"
      }
    }]
  })
}

# CloudWatch Logs policy
resource "aws_iam_role_policy_attachment" "lambda_logs" {
  role       = aws_iam_role.lambda_role.name
  policy_arn = "arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole"
}

# S3 Lambda Layer (dependencies)
resource "aws_lambda_layer_version" "dependencies" {
  filename            = "layer.zip"
  layer_name          = "nodejs-dependencies"
  compatible_runtimes = ["nodejs18.x"]
}

# Lambda function
resource "aws_lambda_function" "api_handler" {
  filename      = "lambda.zip"
  function_name = "api-handler"
  role          = aws_iam_role.lambda_role.arn
  handler       = "index.handler"
  runtime       = "nodejs18.x"
  timeout       = 30
  memory_size   = 256

  layers = [aws_lambda_layer_version.dependencies.arn]

  environment {
    variables = {
      STAGE = "production"
      DB_HOST = var.database_host
    }
  }

  depends_on = [aws_iam_role_policy_attachment.lambda_logs]
}

# API Gateway trigger
resource "aws_lambda_permission" "api_gateway" {
  statement_id  = "AllowAPIGatewayInvoke"
  action        = "lambda:InvokeFunction"
  function_name = aws_lambda_function.api_handler.function_name
  principal     = "apigateway.amazonaws.com"
}

# S3 trigger
resource "aws_lambda_permission" "s3_trigger" {
  statement_id  = "AllowS3Invoke"
  action        = "lambda:InvokeFunction"
  function_name = aws_lambda_function.api_handler.function_name
  principal     = "s3.amazonaws.com"
  source_arn    = aws_s3_bucket.upload_bucket.arn
}

resource "aws_s3_bucket_notification" "bucket_notification" {
  bucket      = aws_s3_bucket.upload_bucket.id
  depends_on  = [aws_lambda_permission.s3_trigger]

  lambda_function {
    lambda_function_arn = aws_lambda_function.api_handler.arn
    events              = ["s3:ObjectCreated:*"]
    filter_prefix       = "uploads/"
    filter_suffix       = ".jpg"
  }
}
```