feat(modules/vnet): Creation of route tables is optional when using t…

…he `vnet` module (#201)

modules/vnet/README.md

@@ -68,7 +68,7 @@ No modules.
 | <a name="input_location"></a> [location](#input\_location) | Location of the resources that will be deployed. | `string` | n/a | yes |
 | <a name="input_network_security_groups"></a> [network\_security\_groups](#input\_network\_security\_groups) | Map of Network Security Groups to create. The key of each entry acts as the Network Security Group name.<br>List of available attributes of each Network Security Group entry:<br>- `location` : (Optional) Specifies the Azure location where to deploy the resource.<br>- `rules`: (Optional) A list of objects representing a Network Security Rule. The key of each entry acts as the name of the rule and<br>    needs to be unique across all rules in the Network Security Group.<br>    List of attributes available to define a Network Security Rule:<br>    - `priority` : Numeric priority of the rule. The value can be between 100 and 4096 and must be unique for each rule in the collection.<br>    The lower the priority number, the higher the priority of the rule.<br>    - `direction` : The direction specifies if rule will be evaluated on incoming or outgoing traffic. Possible values are `Inbound` and `Outbound`.<br>    - `access` : Specifies whether network traffic is allowed or denied. Possible values are `Allow` and `Deny`.<br>    - `protocol` : Network protocol this rule applies to. Possible values include `Tcp`, `Udp`, `Icmp`, or `*` (which matches all).<br>    - `source_port_range` : List of source ports or port ranges.<br>    - `destination_port_range` : Destination Port or Range. Integer or range between `0` and `65535` or `*` to match any.<br>    - `source_address_prefix` : List of source address prefixes. Tags may not be used.<br>    - `destination_address_prefix` : CIDR or destination IP range or `*` to match any IP.<br><br>Example:<pre>{<br>  "network_security_group_1" = {<br>    location = "Australia Central"<br>    rules = {<br>      "AllOutbound" = {<br>        priority                   = 100<br>        direction                  = "Outbound"<br>        access                     = "Allow"<br>        protocol                   = "Tcp"<br>        source_port_range          = "*"<br>        destination_port_range     = "*"<br>        source_address_prefix      = "*"<br>        destination_address_prefix = "*"<br>      },<br>      "AllowSSH" = {<br>        priority                   = 200<br>        direction                  = "Inbound"<br>        access                     = "Allow"<br>        protocol                   = "Tcp"<br>        source_port_range          = "*"<br>        destination_port_range     = "22"<br>        source_address_prefix      = "*"<br>        destination_address_prefix = "*"<br>      }<br>    }<br>  },<br>  "network_security_group_2" = {<br>    rules = {}<br>  }<br>}</pre> | `any` | n/a | yes |
 | <a name="input_resource_group_name"></a> [resource\_group\_name](#input\_resource\_group\_name) | Name of the Resource Group to use. | `string` | n/a | yes |
-| <a name="input_route_tables"></a> [route\_tables](#input\_route\_tables) | Map of objects describing a Route Table. The key of each entry acts as the Route Table name.<br>List of available attributes of each Route Table entry:<br>- `location` : (Optional) Specifies the Azure location where to deploy the resource.<br>- `routes` : (Optional) Map of routes within the Route Table.<br>  List of available attributes of each route entry:<br>  - `address_prefix` : The destination CIDR to which the route applies, such as `10.1.0.0/16`.<br>  - `next_hop_type` : The type of Azure hop the packet should be sent to.<br>    Possible values are: `VirtualNetworkGateway`, `VnetLocal`, `Internet`, `VirtualAppliance` and `None`.<br>  - `next_hop_in_ip_address` : Contains the IP address packets should be forwarded to. <br>    Next hop values are only allowed in routes where the next hop type is `VirtualAppliance`.<br><br>Example:<pre>{<br>  "route_table_1" = {<br>    routes = {<br>      "route_1" = {<br>        address_prefix = "10.1.0.0/16"<br>        next_hop_type  = "vnetlocal"<br>      },<br>      "route_2" = {<br>        address_prefix = "10.2.0.0/16"<br>        next_hop_type  = "vnetlocal"<br>      },<br>    }<br>  },<br>  "route_table_2" = {<br>    routes = {<br>      "route_3" = {<br>        address_prefix         = "0.0.0.0/0"<br>        next_hop_type          = "VirtualAppliance"<br>        next_hop_in_ip_address = "10.112.0.100"<br>      }<br>    },<br>  },<br>}</pre> | `any` | n/a | yes |
+| <a name="input_route_tables"></a> [route\_tables](#input\_route\_tables) | Map of objects describing a Route Table. The key of each entry acts as the Route Table name.<br>List of available attributes of each Route Table entry:<br>- `location` : (Optional) Specifies the Azure location where to deploy the resource.<br>- `routes` : (Optional) Map of routes within the Route Table.<br>  List of available attributes of each route entry:<br>  - `address_prefix` : The destination CIDR to which the route applies, such as `10.1.0.0/16`.<br>  - `next_hop_type` : The type of Azure hop the packet should be sent to.<br>    Possible values are: `VirtualNetworkGateway`, `VnetLocal`, `Internet`, `VirtualAppliance` and `None`.<br>  - `next_hop_in_ip_address` : Contains the IP address packets should be forwarded to. <br>    Next hop values are only allowed in routes where the next hop type is `VirtualAppliance`.<br><br>Example:<pre>{<br>  "route_table_1" = {<br>    routes = {<br>      "route_1" = {<br>        address_prefix = "10.1.0.0/16"<br>        next_hop_type  = "vnetlocal"<br>      },<br>      "route_2" = {<br>        address_prefix = "10.2.0.0/16"<br>        next_hop_type  = "vnetlocal"<br>      },<br>    }<br>  },<br>  "route_table_2" = {<br>    routes = {<br>      "route_3" = {<br>        address_prefix         = "0.0.0.0/0"<br>        next_hop_type          = "VirtualAppliance"<br>        next_hop_in_ip_address = "10.112.0.100"<br>      }<br>    },<br>  },<br>}</pre> | `map` | `{}` | no |
 | <a name="input_subnets"></a> [subnets](#input\_subnets) | Map of subnet objects to create within a virtual network. The key of each entry acts as the subnet name.<br>List of available attributes of each subnet entry:<br>- `address_prefixes` : The address prefix to use for the subnet.<br>- `network_security_group_id` : The Network Security Group identifier to associate with the subnet.<br>- `route_table_id` : The Route Table identifier to associate with the subnet.<br>- `tags` : (Optional) Map of tags to assign to the resource.<br><br>Example:<pre>{<br>  "management" = {<br>    address_prefixes       = ["10.100.0.0/24"]<br>    network_security_group = "network_security_group_1"<br>    route_table            = "route_table_1"<br>  },<br>  "private" = {<br>    address_prefixes       = ["10.100.1.0/24"]<br>    network_security_group = "network_security_group_2"<br>    route_table            = "route_table_2"<br>  },<br>  "public" = {<br>    address_prefixes       = ["10.100.2.0/24"]<br>    network_security_group = "network_security_group_3"<br>    route_table            = "route_table_3"<br>  },<br>}</pre> | `any` | n/a | yes |
 | <a name="input_tags"></a> [tags](#input\_tags) | Map of tags to assign to all of the created resources. | `map(any)` | `{}` | no |
 | <a name="input_virtual_network_name"></a> [virtual\_network\_name](#input\_virtual\_network\_name) | The name of the Azure Virtual Network. | `string` | n/a | yes |

modules/vnet/variables.tf

@@ -124,6 +124,7 @@ variable "route_tables" {
   }
   ```
   EOF
+  default     = {}
 }
 
 variable "subnets" {