Terraform - Resource not found for variable despite having it declared in the same file

Question

Terraform can't find a resource which is declared in the same file where the reference is.

It seems that this line is causing trouble: role_arn = "${aws_iam_role.newsapi_lambda_codepipeline.arn}". It can't find newsapi_lambda_codepipeline which is declared as resource "aws_iam_role" "newsapi_lambda_codepipeline" { ... }.

This is my main.tf:

resource "aws_s3_bucket" "newsapi_lambda_builds" {
  bucket = "newsapi-lambda-builds"
  acl    = "private"
}

resource "aws_iam_role" "newsapi_lambda_codebuild" {
  name = "newsapi-lambda-codebuild"

  assume_role_policy = <<EOF
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Action": [
        "s3:GetObject",
        "s3:GetObjectVersion",
        "s3:GetBucketVersioning"
      ],
      "Resource": "arn:aws:s3:::newsapi_lambda_builds",
      "Effect": "Allow"
    },
    {
      "Action": [
        "s3:PutObject"
      ],
      "Resource": [
        "arn:aws:s3:::newsapi_lambda_builds"
      ],
      "Effect": "Allow"
    },
    {
      "Action": [
        "lambda:invokefunction",
        "lambda:listfunctions"
      ],
      "Resource": "*",
      "Effect": "Allow"
    },
    {
      "Effect": "Allow",
      "Resource": [
        "*"
      ],
      "Action": [
        "logs:CreateLogGroup",
        "logs:CreateLogStream",
        "logs:PutLogEvents"
      ]
    }
  ]
}
EOF
}
resource "aws_iam_role" "newsapi_lambda_codepipeline" {
  name = "newsapi-lambda-codepipeline"

  assume_role_policy = <<EOF
{
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Service": "codepipeline.amazonaws.com"
      },
      "Action": "sts:AssumeRole"
    },
    {
      "Action": [
        "s3:GetObject",
        "s3:GetObjectVersion",
        "s3:GetBucketVersioning"
      ],
      "Resource": "${aws_s3_bucket.newsapi_lambda_builds.arn}",
      "Resource": "${aws_s3_bucket.newsapi_lambda_builds.arn}/*"
      "Effect": "Allow"
    },
    {
      "Action": [
        "s3:PutObject"
      ],
      "Resource": [
        "arn:aws:s3:::newsapi_lambda_builds"
      ],
      "Effect": "Allow"
    },
    {
      "Effect": "Allow",
      "Action": [
        "codebuild:BatchGetBuilds",
        "codebuild:StartBuild"
      ],
      "Resource": "*"
    }
  ],
  "Version": "2012-10-17"
}
EOF
}


resource "aws_codepipeline" "newsapi_lambda" {
  name     = "newsapi-lambda"
  role_arn = "${aws_iam_role.newsapi_lambda_codepipeline.arn}"

  artifact_store {
    location = "${aws_s3_bucket.newsapi_lambda_builds.bucket}"
    type     = "S3"
  }

  stage {
    name = "Source"

    action {
      name             = "Source"
      category         = "Source"
      owner            = "ThirdParty"
      provider         = "GitHub"
      version          = "1"
      output_artifacts = ["newsapi_lambda"]

      configuration {
        Owner      = "Defozo"
        Repo       = "traceitfor.me_newsapi_lambda"
        Branch     = "master"
      }
    }
  }

  stage {
    name = "Build"

    action {
      name            = "Build"
      category        = "Build"
      owner           = "AWS"
      provider        = "CodeBuild"
      input_artifacts = ["newsapi_lambda"]
      version         = "1"
      role_arn = "${aws_iam_role.newsapi_lambda_codebuild.arn}"

      configuration {
        ProjectName = "newsapi-lambda"
      }
    }
  }
}

After executing terraform apply I get:

Error: Error running plan: 1 error(s) occurred:

* aws_codepipeline.newsapi_lambda: 1 error(s) occurred:

* aws_codepipeline.newsapi_lambda: Resource 'aws_iam_role.newsapi_lambda_codepipeline' not found for variable 'aws_iam_role.newsapi_lambda_codepipeline.arn'

I don't understand why that happens. I have aws_iam_role.newsapi_lambda_codepipeline declared, haven't I?

Answer 1

For those experiencing an issue with aws_ecs_task_definition not finding a variable for the aws_ecs_task_definition.XXX.arn, there's a good chance your JSON came out malformed. Here's what I did to remedy my issue

• Replace your line with task_definition = "[]"
• Run terraform plan

At this point you should get an error. For example, I got

module.tf.aws_ecs_task_definition.sandbox: ECS Task Definition container_definitions is invalid: Error decoding JSON: json: cannot unmarshal string into Go struct field ContainerDefinition.MemoryReservation of type int64

In this case, I had quoted memSize in my template_file and it didn't implicitly convert to int64, hence an error.

I changed "memoryReservation": "${mem_size}" to "memoryReservation": ${mem_size}, removed the task_definition placeholder, and everything went smoothly.