feat(module/loadbalancer): add session persitance to the available op…

…tions (#195)

modules/loadbalancer/README.md

@@ -94,7 +94,7 @@ No modules.
 | <a name="input_avzones"></a> [avzones](#input\_avzones) | After provider version 3.x you need to specify in which availability zone(s) you want to place IP.<br>ie: for zone-redundant with 3 availability zone in current region value will be:<pre>["1","2","3"]</pre> | `list(string)` | `[]` | no |
 | <a name="input_backend_name"></a> [backend\_name](#input\_backend\_name) | The name of the backend pool to create. If an empty name is provided, it will be auto-generated.<br>All the frontends of the load balancer always use the same single backend. | `string` | `""` | no |
 | <a name="input_enable_zones"></a> [enable\_zones](#input\_enable\_zones) | If false, all the subnet-associated frontends and also all created Public IP addresses default to not to use Availability Zones (the `No-Zone` setting). It is intended for the regions that do not yet support Availability Zones. | `bool` | `true` | no |
-| <a name="input_frontend_ips"></a> [frontend\_ips](#input\_frontend\_ips) | A map of objects describing LB frontend IP configurations. Used for both public or private load balancers. <br>Keys of the map are the names of the created load balancers.<br><br>Public LB<br><br>- `create_public_ip` : Optional. Set to `true` to create a public IP.<br>- `public_ip_name` : Ignored if `create_public_ip` is `true`. The existing public IP resource name to use.<br>- `public_ip_resource_group` : Ignored if `create_public_ip` is `true` or if `public_ip_name` is null. The name of the resource group which holds `public_ip_name`.<br><br>Example<pre>frontend_ips = {<br>  pip_existing = {<br>    create_public_ip         = false<br>    public_ip_name           = "my_ip"<br>    public_ip_resource_group = "my_rg_name"<br>    rules = {<br>      HTTP = {<br>        port         = 80<br>        protocol     = "Tcp"<br>      }<br>    }<br>  }<br>}</pre>Private LB<br><br>- `subnet_id` : Identifier of an existing subnet.<br>- `private_ip_address_allocation` : Type of private allocation: `Static` or `Dynamic`.<br>- `private_ip_address` : If `Static`, the private IP address.<br><br>Example<pre>frontend_ips = {<br>  internal_fe = {<br>    subnet_id                     = azurerm_subnet.this.id<br>    private_ip_address_allocation = "Static"<br>    private_ip_address            = "192.168.0.10"<br>    rules = {<br>      HA_PORTS = {<br>        port         = 0<br>        protocol     = "All"<br>      }<br>    }<br>  }<br>}</pre>Zone usage<br><br>You can specifies a list of Availability Zones in which the IP Address for this Load Balancer should be located.<br><br>- `zones` : Specify in which zones you want to create frontend IP address. Pass list with zone coverage, ie: `["1","2","3"]`<br><br>Example<pre>frontend_ips = {<br>  internal = {<br>    subnet_id                     = azurerm_subnet.this.id<br>    private_ip_address_allocation = "Static"<br>    private_ip_address            = "192.168.0.10"<br>    zones                         = ["1","2","3"]<br>  }<br>}</pre> | `any` | n/a | yes |
+| <a name="input_frontend_ips"></a> [frontend\_ips](#input\_frontend\_ips) | A map of objects describing LB frontend IP configurations. Used for both public or private load balancers. <br>Keys of the map are the names of the created load balancers.<br><br>Public LB<br><br>- `create_public_ip` : Optional. Set to `true` to create a public IP.<br>- `public_ip_name` : Ignored if `create_public_ip` is `true`. The existing public IP resource name to use.<br>- `public_ip_resource_group` : Ignored if `create_public_ip` is `true` or if `public_ip_name` is null. The name of the resource group which holds `public_ip_name`.<br><br>Example<pre>frontend_ips = {<br>  pip_existing = {<br>    create_public_ip         = false<br>    public_ip_name           = "my_ip"<br>    public_ip_resource_group = "my_rg_name"<br>    rules = {<br>      HTTP = {<br>        port         = 80<br>        protocol     = "Tcp"<br>      }<br>    }<br>  }<br>}</pre>Private LB<br><br>- `subnet_id` : Identifier of an existing subnet.<br>- `private_ip_address_allocation` : Type of private allocation: `Static` or `Dynamic`.<br>- `private_ip_address` : If `Static`, the private IP address.<br><br>Example<pre>frontend_ips = {<br>  internal_fe = {<br>    subnet_id                     = azurerm_subnet.this.id<br>    private_ip_address_allocation = "Static"<br>    private_ip_address            = "192.168.0.10"<br>    rules = {<br>      HA_PORTS = {<br>        port         = 0<br>        protocol     = "All"<br>      }<br>    }<br>  }<br>}</pre>Zone usage<br><br>You can specifies a list of Availability Zones in which the IP Address for this Load Balancer should be located.<br><br>- `zones` : Specify in which zones you want to create frontend IP address. Pass list with zone coverage, ie: `["1","2","3"]`<br><br>Example<pre>frontend_ips = {<br>  internal = {<br>    subnet_id                     = azurerm_subnet.this.id<br>    private_ip_address_allocation = "Static"<br>    private_ip_address            = "192.168.0.10"<br>    zones                         = ["1","2","3"]<br>  }<br>}</pre>Session persistence/Load distribution<br><br>By default the Load Balancer uses a 5 tuple hash to map traffic to available servers. This can be controlled using `session_persistence` property defined inside a role. Available values are:<br><br>- `Default` : this is the 5 tuple hash - this method is also used when no property is defined<br>- `SourceIP` : a 2 tuple hash is used<br>- `SourceIPProtocol` : a 3 tuple hash is used<br><br>Example<pre>frontend_ips = {<br>    rule_1 = {<br>      create_public_ip = true<br>      rules = {<br>        HTTP = {<br>          port     = 80<br>          protocol = "Tcp"<br>          session_persistence = "SourceIP"<br>        }<br>      }<br>    }<br>  }</pre> | `any` | n/a | yes |
 | <a name="input_location"></a> [location](#input\_location) | Region to deploy load balancer and dependencies. | `string` | n/a | yes |
 | <a name="input_name"></a> [name](#input\_name) | The name of the load balancer. | `string` | n/a | yes |
 | <a name="input_network_security_allow_source_ips"></a> [network\_security\_allow\_source\_ips](#input\_network\_security\_allow\_source\_ips) | List of IP CIDR ranges (such as `["192.168.0.0/16"]` or `["*"]`) from which the inbound traffic to all frontends should be allowed.<br>If it's empty, user is responsible for configuring a Network Security Group separately, possibly using the `frontend_combined_rules` output.<br>The list cannot include Azure tags like "Internet" or "Sql.EastUS". | `list(string)` | `[]` | no |

modules/loadbalancer/main.tf

@@ -140,6 +140,7 @@ resource "azurerm_lb_rule" "lb_rules" {
   frontend_port                  = each.value.rule.port
   enable_floating_ip             = true
   disable_outbound_snat          = local.disable_outbound_snat
+  load_distribution              = try(each.value.rule.session_persistence, null)
 }
 
 resource "azurerm_lb_outbound_rule" "outb_rules" {

modules/loadbalancer/variables.tf

@@ -69,6 +69,31 @@ variable "frontend_ips" {
     }
   }
   ```
+
+  Session persistence/Load distribution
+
+  By default the Load Balancer uses a 5 tuple hash to map traffic to available servers. This can be controlled using `session_persistence` property defined inside a role. Available values are:
+
+  - `Default` : this is the 5 tuple hash - this method is also used when no property is defined
+  - `SourceIP` : a 2 tuple hash is used
+  - `SourceIPProtocol` : a 3 tuple hash is used
+
+  Example
+
+  ```
+    frontend_ips = {
+      rule_1 = {
+        create_public_ip = true
+        rules = {
+          HTTP = {
+            port     = 80
+            protocol = "Tcp"
+            session_persistence = "SourceIP"
+          }
+        }
+      }
+    }
+  ```
   EOF
 }
 variable "outbound_rules" {