Functions#

https://www.terraform.io/language/functions

func_name(arg1, arg2, ...)

Common Functions#

  • Numeric: min(42, 13, 7)

  • String: lower(“TEST”)

  • Collection: merge(map1, map2)

  • IP Network: cidrsubnet()

  • File system: file(path)

  • Type Conversion: toset()

Examples#

try terraform functions with terraform console

$ terraform console
> min(12, 23, 1, 30)
1
> lower("TEST")
"test"
>
> var.vpc_cidr_block
tomap({
"private" = "10.1.0.0/16"
"public" = "192.168.0.0/16"
})
> lookup(var.vpc_cidr_block, "public")
"192.168.0.0/16"
> lookup(var.vpc_cidr_block, "public1")
╷
│ Error: Error in function call
│
│   on <console-input> line 1:
│   (source code not available)
│
│ Call to function "lookup" failed: lookup failed to find key "public1".
╵


> lookup(var.vpc_cidr_block, "public1", "unknow")
"unknow"
>
> merge(var.vpc_cidr_block, {"public1": "1.1.1.1/32"})
{
"private" = "10.1.0.0/16"
"public" = "192.168.0.0/16"
"public1" = "1.1.1.1/32"
}

file and templatefile

$ terraform console
> file("${path.module}/main.tf")
<<EOT
# # use count
# resource "aws_vpc" "vpc" {

#   count                = 2
#   cidr_block           = "10.${count.index}.0.0/16"
#   enable_dns_hostnames = var.enable_dns_hostnames
#   tags                 = {
#     Name = "terraform-vpc-${count.index}"
#   }
# }

# # Create a Subnet
# output "vpc_id" {
#   value = aws_vpc.vpc[0].id
# }
resource "aws_vpc" "vpc2" {

for_each             = var.vpc_cidr_block
cidr_block           = each.value
enable_dns_hostnames = var.enable_dns_hostnames
tags = {
    Name = "terraform-vpc-${each.key}"
}

}

EOT
>

> file("${path.module}/test.tpl")
"hello world ${name}"
>

> templatefile("test.tpl", {"name": "terraform"})
"hello world terraform"
>