Lambda functions should have X-Ray tracing enabled

Explanation

X-Ray tracing enables end-to-end debugging and analysis of all function activity. This will allow for identifying bottlenecks, slow downs and timeouts.

Possible Impact

WIthout full tracing enabled it is difficult to trace the flow of logs

Suggested Resolution

Enable tracing

Insecure Example

The following example will fail the aws-lambda-enable-tracing check.

resource "aws_iam_role" "iam_for_lambda" {
  name = "iam_for_lambda"

  assume_role_policy = <<EOF
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Action": "sts:AssumeRole",
      "Principal": {
        "Service": "lambda.amazonaws.com"
      },
      "Effect": "Allow",
      "Sid": ""
    }
  ]
}
EOF
}

resource "aws_lambda_function" "bad_example" {
  filename      = "lambda_function_payload.zip"
  function_name = "lambda_function_name"
  role          = aws_iam_role.iam_for_lambda.arn
  handler       = "exports.test"

  # The filebase64sha256() function is available in Terraform 0.11.12 and later
  # For Terraform 0.11.11 and earlier, use the base64sha256() function and the file() function:
  # source_code_hash = "${base64sha256(file("lambda_function_payload.zip"))}"
  source_code_hash = filebase64sha256("lambda_function_payload.zip")

  runtime = "nodejs12.x"

  environment {
    variables = {
      foo = "bar"
    }
  }
  tracing_config {
    mode = ""
  }
}

Secure Example

The following example will pass the aws-lambda-enable-tracing check.

resource "aws_iam_role" "iam_for_lambda" {
  name = "iam_for_lambda"

  assume_role_policy = <<EOF
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Action": "sts:AssumeRole",
      "Principal": {
        "Service": "lambda.amazonaws.com"
      },
      "Effect": "Allow",
      "Sid": ""
    }
  ]
}
EOF
}

resource "aws_lambda_function" "good_example" {
  filename      = "lambda_function_payload.zip"
  function_name = "lambda_function_name"
  role          = aws_iam_role.iam_for_lambda.arn
  handler       = "exports.test"

  # The filebase64sha256() function is available in Terraform 0.11.12 and later
  # For Terraform 0.11.11 and earlier, use the base64sha256() function and the file() function:
  # source_code_hash = "${base64sha256(file("lambda_function_payload.zip"))}"
  source_code_hash = filebase64sha256("lambda_function_payload.zip")

  runtime = "nodejs12.x"

  environment {
    variables = {
      foo = "bar"
    }
  }
  tracing_config {
    mode = "something"
  }
}

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