How to correct this error in creating Azure NSG with Terraform?

Question

I am trying to create a NSG in Azure with Terraform.

Terraform Version is v0.15.2 with provider version azurerm v2.61.0

Here's the piece of code in my TF file.

  resource "azurerm_network_security_group" "nsg" {
  name                = "SG"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name


  security_rule = [{
    access                                     = "Allow"
    description                                = "SSH Rule"
    destination_address_prefix                 = "*"
    destination_address_prefixes               = ["*"]
    destination_port_range                     = "*"
    destination_port_ranges                    = ["22"]
    direction                                  = "Inbound"
    name                                       = "SSH Rule"
    priority                                   = 100
    protocol                                   = "Tcp"
    source_address_prefix                      = "*"
    source_address_prefixes                    = ["*"]
    source_port_range                          = "22"
    source_port_ranges                         = ["22"]
    source_application_security_group_ids      = [""]
    destination_application_security_group_ids = [""]

  }]
}

Now when I run terraform plan & terraform apply, I get the expected output as:

* only one of "source_port_range" and "source_port_ranges" can be used per security rule
* only one of "destination_port_range" and "destination_port_ranges" can be used per security rule
* only one of "source_address_prefix" and "source_address_prefixes" can be used per security rule
* only one of "destination_address_prefix" and "destination_address_prefixes" can be used per security rule

Now when I keep only source_port_range, destination_port_range, source_address_prefix, destination_address_prefix fields & run terraform plan again, it gives me following error:

Inappropriate value for attribute "security_rule": element 0: attributes "destination_address_prefixes",
│ "destination_port_ranges", "source_address_prefixes", and "source_port_ranges" are required.

If I add those & remove the earlier ones, I get:

│ Inappropriate value for attribute "security_rule": element 0: attributes "destination_address_prefix", "destination_port_range",  
│ "source_address_prefix", and "source_port_range" are required.

Why is this happening & how to get around with this issue?

Update

Took into consideration the point mentioned in the comment & made few changes to get it working.

Points to note:

• Even when it's mentioned Optional in the doc, Terraform needs all the keys in the security_rule block.
• Also, it doesn't allow Source/destination address_prefixes = ["*"] like this. Source/Destination address_prefix did the job.
• And where values are not mentioned, [] is expected instead of [""]

resource "azurerm_network_security_group" "nsg" {
  name                = "SG"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name


  security_rule = [{
    access                                     = "Allow"
    description                                = "SSH Rule"
    destination_address_prefix                 = "*"
    destination_address_prefixes               = []
    destination_port_range                     = ""
    destination_port_ranges                    = ["22"]
    direction                                  = "Inbound"
    name                                       = "SSH Rule"
    priority                                   = 100
    protocol                                   = "Tcp"
    source_address_prefix                      = "*"
    source_address_prefixes                    = []
    source_port_range                          = "*"
    source_port_ranges                         = []
    source_application_security_group_ids      = []
    destination_application_security_group_ids = []

  }]
}

Answer 1

Can you try this:

  security_rule = [{
    access                                     = "Allow"
    description                                = "SSH Rule"
    destination_address_prefix                 = ""
    destination_address_prefixes               = ["*"]
    destination_port_range                     = ""
    destination_port_ranges                    = ["22"]
    direction                                  = "Inbound"
    name                                       = "SSH Rule"
    priority                                   = 100
    protocol                                   = "Tcp"
    source_address_prefix                      = ""
    source_address_prefixes                    = ["*"]
    source_port_range                          = ""
    source_port_ranges                         = ["22"]
    source_application_security_group_ids      = []
    destination_application_security_group_ids = []

  }]
}

You're defining values in both fields - i.e. Terraform will only accept one of either destination_port_range or destination_port_ranges and not both. Same goes for the other attributes.