Loading a CSV file into terraform

2 min read

Sometimes if you have some externally managed data it can come handy to be able to import it into terraform as a CSV file instead of having to manually enter all the date. To do so we can use the csvdecode() function

10/08/2021

terraform: Using for_each over tuples

2 min read

Let's imagine we have the following data structure:

locals {
  queries = [
    {
      query  = "SELECT version()"
      engine = "postgresql"
    },
    {
      query  = "SELECT * FROM v$version"
      engine = "oracle"
    },
    (...)
  ]
}

If we want to use just some of the items on a resource we can use for_each through the resulting array of filtering the objects using a for:

for_each = [ for item in local.queries: item if item.engine == "postgresql" ]

22/06/2021

terraform: create an array of resources using for_each

3 min read

If we need to create multiple resources of the same kind based on a set of objects, we can use the for_each keyword for creating them.

08/06/2021

terraform: Using dynamic blocks to conditionally set a block on a resource

2 min read

In the same way we can conditionally include a resource, we can also use for_each to conditionally include a nested block using terraform's dynamic blocks

For example, if we want to add a variable that controls whether we should set this value:

resource "helm_release" "spinnaker" {
  name  = "spinnaker"

  (...)

  set {
    name = "halyard.additionalScripts.data.enable_mptv2"
    type = "string"
    value = <<-EOF
      #!/bin/sh
      cat $0
      echo "custom mptv2"
      $HAL_COMMAND config features edit --managed-pipeline-templates-v2-ui true
    EOF
  }
}

28/05/2021

Terraform dynamic blocks

3 min read

When we have a resource that can have multiple nested blocks to be configured we can use dynamic blocks to configure it dynamically. A perfect example is a SecurityGroup that can have multiple ingress and egress rules to be able to allow traffic. Let's use the following aws_security_group resource definition as a starting point:

resource "aws_security_group" "demo_sg" {
  name = "demo_sg"
  description = "pet2cattle demo SG with dynamic blocks"
  vpc_id = aws_vpc.main.id

  ingress {
    from_port        = 443
    to_port          = 443
    protocol         = "tcp"
    cidr_blocks      = [aws_vpc.main.cidr_block]
  }

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

27/05/2021