I want to create 5 machines (3 frontend, 1 LoadBalncer and 1 db). I want to ensure that all VMs have /etc/hosts entries pointing to each other with the following entries:

vm1 10.0.x.x
vm2 10.0.x.x
vm3 10.0.x.x
vm4 10.0.x.x
vm5 10.0.x.x

And when IPs or hostnames changed, rerunning the terraform should update the /etc/hosts.

Below is snippet of my terraform code:

resource "azurerm_linux_virtual_machine" "frontend_vm" {
  count                 = 3
  name                  = "frontend-vm${count.index + 1}"
  location              = azurerm_resource_group.main.location
  resource_group_name   = azurerm_resource_group.main.name
  size                  = "Standard_B1s"
  admin_username        = "adminuser"
  network_interface_ids = [azurerm_network_interface.frontend_nic[count.index].id]

  admin_password = "Test@1234"
  disable_password_authentication = false

  os_disk {
    caching              = "ReadWrite"
    storage_account_type = "Standard_LRS"
  }

  source_image_reference {
    publisher = "Canonical"
    offer     = "UbuntuServer"
    sku       = "18.04-LTS"
    version   = "latest"
  }
}


resource "azurerm_linux_virtual_machine" "loadbalancer_vm" {
  name                  = "loadbalancer-vm"
  location              = azurerm_resource_group.main.location
  resource_group_name   = azurerm_resource_group.main.name
  size                  = "Standard_B1s"
  admin_username        = "adminuser"
  network_interface_ids = [azurerm_network_interface.loadbalancer_nic.id]

 admin_password = "Test@1234"
 disable_password_authentication = false

  os_disk {
    caching              = "ReadWrite"
    storage_account_type = "Standard_LRS"
  }

  source_image_reference {
    publisher = "Canonical"
    offer     = "UbuntuServer"
    sku       = "18.04-LTS"
    version   = "latest"
  }


}

resource "azurerm_linux_virtual_machine" "database_vm" {
  name                  = "database-vm"
  location              = azurerm_resource_group.main.location
  resource_group_name   = azurerm_resource_group.main.name
  size                  = "Standard_B1s"
  admin_username        = "adminuser"
  network_interface_ids = [azurerm_network_interface.database_nic.id]

 admin_password = "Test@1234"
 disable_password_authentication = false

  os_disk {
    caching              = "ReadWrite"
    storage_account_type = "Standard_LRS"
  }

  source_image_reference {
    publisher = "Canonical"
    offer     = "UbuntuServer"
    sku       = "18.04-LTS"
    version   = "latest"
  }

}

May be we can use remote-exec but I’m not familiar with that. Any help will be highly appreciated.