deflock/terraform/modules/alpr_counts/main.tf

resource "aws_iam_role" "lambda_role" {
  name = "lambda_s3_write_role"

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

resource "aws_iam_policy" "lambda_s3_write_policy" {
  name        = "lambda_s3_write_policy"
  description = "Policy for Lambda to write to S3 bucket ${var.deflock_stats_bucket}"

  policy = jsonencode({
    Version = "2012-10-17"
    Statement = [
      {
        Action = [
          "s3:PutObject",
          "s3:PutObjectAcl"
        ]
        Effect   = "Allow"
        Resource = "arn:aws:s3:::${var.deflock_stats_bucket}/${var.output_filename}"
      }
    ]
  })
}

resource "aws_iam_role_policy_attachment" "lambda_s3_write_attachment" {
  role       = aws_iam_role.lambda_role.name
  policy_arn = aws_iam_policy.lambda_s3_write_policy.arn
}

resource "aws_ecr_repository" "lambda_repository" {
  name = "${var.module_name}-lambda"
}

resource "aws_lambda_function" "overpass_lambda" {
  function_name = var.module_name
  role          = aws_iam_role.lambda_role.arn
  package_type  = "Image"
  image_uri     = "${aws_ecr_repository.lambda_repository.repository_url}:latest"
  timeout       = 180
  architectures = ["arm64"]

  environment {
    variables = {
      OUTPUT_BUCKET = var.deflock_stats_bucket
      OUTPUT_KEY    = var.output_filename
    }
  }
}

resource "aws_cloudwatch_event_rule" "lambda_rule" {
  name        = "${var.module_name}_rule"
  description = "Rule to trigger ${var.module_name} lambda"
  schedule_expression = var.rate
}

resource "aws_cloudwatch_event_target" "lambda_target" {
  target_id = "${var.module_name}_target"
  rule      = aws_cloudwatch_event_rule.lambda_rule.name
  arn       = aws_lambda_function.overpass_lambda.arn
}

resource "aws_lambda_permission" "allow_cloudwatch_to_call_lambda" {
  statement_id  = "AllowExecutionFromCloudWatch"
  action        = "lambda:InvokeFunction"
  function_name = aws_lambda_function.overpass_lambda.function_name
  principal     = "events.amazonaws.com"
  source_arn    = aws_cloudwatch_event_rule.lambda_rule.arn
}

resource "aws_cloudwatch_log_group" "lambda_log_group" {
  name              = "/aws/lambda/${var.module_name}"
  retention_in_days = 14
}

resource "aws_iam_policy" "lambda_cloudwatch_logs_policy" {
  name        = "lambda_cloudwatch_logs_policy"
  description = "Policy for Lambda to write logs to CloudWatch"

  policy = jsonencode({
    Version = "2012-10-17",
    Statement = [
      {
        Action = [
          "logs:CreateLogGroup",
          "logs:CreateLogStream",
          "logs:PutLogEvents"
        ]
        Effect   = "Allow"
        Resource = "arn:aws:logs:${var.aws_region}:${var.aws_account_id}:log-group:/aws/lambda/${var.module_name}:*"
      }
    ]
  })
}

resource "aws_iam_role_policy_attachment" "lambda_cloudwatch_logs_attachment" {
  role       = aws_iam_role.lambda_role.name
  policy_arn = aws_iam_policy.lambda_cloudwatch_logs_policy.arn
}

# Alarms for Failure

resource "aws_cloudwatch_metric_alarm" "lambda_error_alarm" {
  alarm_name          = "${var.module_name}_execution_error"
  alarm_description   = "An error has occurred while executing the ${var.module_name} Lambda"
  comparison_operator = "GreaterThanThreshold"
  evaluation_periods  = 1
  metric_name         = "Errors"
  namespace           = "AWS/Lambda"
  period              = 86400 # 1 day
  statistic           = "Sum"
  threshold           = 0
  dimensions = {
    FunctionName = aws_lambda_function.overpass_lambda.function_name
  }

  alarm_actions = [var.sns_topic_arn]
}