Support named (non-default) Backend Address Pools for Load Balancers (c…

…loudfoundry#644)

Note: The new, optional `load_balancer/backend_pool_name` sub-property is an optional key of each LB Hash config (whether specifying an Array of LBs or a single LB).

Note: This maintains/restores functional symmetry between the LB and AGW configs (although the symmetric LB functionality was not an explicitly requested part of the feature enhancements for cloudfoundry#644, adding the feature only for AGWs would break functional symmetry).

---

SQUASHED COMMIT HISTORY:

issue-644: named-pool-LB: Added a new, optional `load_balancer/backend_pool_name` sub-property for the `load_balancer` config.
Note: The new sub-property is an optional key of each LB Hash config, whether specifying an Array of LBs or a single LB.

src/bosh_azure_cpi/lib/cloud/azure/models/config.rb

@@ -2,14 +2,16 @@
 
 module Bosh::AzureCloud
   class LoadBalancerConfig
-    attr_reader :name, :resource_group_name
-    def initialize(resource_group_name, name)
+    attr_reader :name, :resource_group_name, :backend_pool_name
+
+    def initialize(resource_group_name, name, backend_pool_name = nil)
       @resource_group_name = resource_group_name
       @name = name
+      @backend_pool_name = backend_pool_name
     end
 
     def to_s
-      "name: #{@name}, resource_group_name: #{@resource_group_name}"
+      "name: #{@name}, resource_group_name: #{@resource_group_name}, backend_pool_name: #{@backend_pool_name}"
     end
   end
 

src/bosh_azure_cpi/lib/cloud/azure/models/vm_cloud_props.rb

@@ -115,14 +115,17 @@ def _parse_load_balancer_config(vm_properties, global_azure_config)
         if lbc.is_a?(Hash)
           load_balancer_names = lbc[NAME_KEY]
           resource_group_name = lbc[RESOURCE_GROUP_NAME_KEY]
+          backend_pool_name = lbc[BACKEND_POOL_NAME_KEY]
         else
           load_balancer_names = lbc
           resource_group_name = nil
+          backend_pool_name = nil
         end
         String(load_balancer_names).split(',').map do |load_balancer_name|
           Bosh::AzureCloud::LoadBalancerConfig.new(
             resource_group_name || global_azure_config.resource_group_name,
-            load_balancer_name
+            load_balancer_name,
+            backend_pool_name
           )
         end
       end

src/bosh_azure_cpi/lib/cloud/azure/vms/vm_manager_network.rb

@@ -94,9 +94,24 @@ def _get_load_balancers(vm_props)
       load_balancers = nil
       load_balancer_configs = vm_props.load_balancers
       unless load_balancer_configs.nil?
+        # NOTE: The following block gets the Azure API info for each Bosh AGW config (from the vm_type config).
         load_balancers = load_balancer_configs.map do |load_balancer_config|
           load_balancer = @azure_client.get_load_balancer_by_name(load_balancer_config.resource_group_name, load_balancer_config.name)
           cloud_error("Cannot find the load balancer '#{load_balancer_config.name}'") if load_balancer.nil?
+
+          if load_balancer_config.backend_pool_name
+            # NOTE: This is the only place where we simultaneously have both the Bosh LB config (from the vm_type) AND the Azure LB info (from the Azure API).
+            # Since the `AzureClient.create_network_interface` method only uses the first backend pool,
+            # and since there is not a 1-to-1 mapping between the vm_type LB configs and LBs (despite the config property name, each vm_type LB config actually represents a single LB Backend Pool, not a whole LB),
+            # we can therefore remove all pools EXCEPT the specified pool.
+            # To handle multiple pools of a single LB, you should use 1 vm_type LB Hash (with LB name + backend_pool_name) per pool.
+            pools = load_balancer[:backend_address_pools]
+            pools = [pools] unless pools.is_a?(Array)
+            pool = pools.find { |p| Hash(p)[:name] == load_balancer_config.backend_pool_name }
+            cloud_error("'#{load_balancer_config.name}' does not have a backend_pool named '#{load_balancer_config.backend_pool_name}': #{load_balancer}") if pool.nil?
+
+            load_balancer[:backend_address_pools] = [pool]
+          end
           load_balancer
         end
       end

src/bosh_azure_cpi/spec/unit/azure_client/create_network_interface_spec.rb

@@ -363,6 +363,36 @@
             azure_client.create_network_interface(resource_group, nic_params)
           end.not_to raise_error
         end
+
+        context 'with multiple backend pools' do
+          # TODO: issue-644: multi-BEPool-LB: add unit tests for multi-pool LBs
+          it 'should create a network interface without error'
+
+          context 'when backend_pool_name is specified' do
+            # TODO: issue-644: multi-BEPool-LB: add unit tests for named-pool LBs
+            it 'should use the specified backend_pool'
+          end
+
+          context 'when an invalid backend_pool_name is specified' do
+            # TODO: issue-644: multi-BEPool-LB: add unit tests for named-pool LBs
+            it 'should raise an error'
+          end
+        end
+      end
+
+      context 'with multiple load balancers' do # rubocop:disable RSpec/RepeatedExampleGroupBody
+        # TODO: issue-644: multi-LB: add unit tests for multi-LBs
+        it 'should create a network interface without error'
+
+        context 'with multiple backend pools' do
+          # TODO: issue-644: multi-BEPool-LB: add unit tests for multi-pool LBs
+          it 'should create a network interface without error'
+
+          context 'when backend_pool_name is specified' do
+            # TODO: issue-644: multi-BEPool-LB: add unit tests for named-pool LBs
+            it 'should use the specified backend_pool'
+          end
+        end
       end
 
       context 'with application security groups' do
@@ -556,7 +586,7 @@
         end
       end
 
-      context 'with multiple application gateways' do
+      context 'with multiple application gateways' do # rubocop:disable RSpec/RepeatedExampleGroupBody
         # TODO: issue-644: multi-AGW: add unit tests for multi-AGWs
         it 'should create a network interface without error'
 

src/bosh_azure_cpi/spec/unit/models/load_balancer_config_spec.rb

@@ -7,11 +7,12 @@
     context 'when called' do
       let(:name) { 'fake_name' }
       let(:resource_group_name) { 'fake_rg' }
-      let(:lb_string) { "name: #{name}, resource_group_name: #{resource_group_name}" }
-      let(:load_balancer_config) { Bosh::AzureCloud::LoadBalancerConfig.new(resource_group_name, name) }
+      let(:backend_pool_name) { 'fake_pool' }
+      let(:expected_string) { "name: #{name}, resource_group_name: #{resource_group_name}, backend_pool_name: #{backend_pool_name}" }
+      let(:load_balancer_config) { Bosh::AzureCloud::LoadBalancerConfig.new(resource_group_name, name, backend_pool_name) }
 
       it 'should return the correct string' do
-        expect(load_balancer_config.to_s).to eq(lb_string)
+        expect(load_balancer_config.to_s).to eq(expected_string)
       end
     end
   end

src/bosh_azure_cpi/spec/unit/vm_manager/create/dynamic_public_ip_spec.rb

@@ -76,6 +76,33 @@
             expect(vm_params[:name]).to eq(vm_name)
           end
 
+          context 'with single load_balancer' do
+            context 'when load_balancer has multiple backend pools' do
+              # TODO: issue-644: multi-BEPool-LB: add unit tests for multi-pool LBs
+              it 'adds the public IP to the default pool'
+
+              context 'when backend_pool_name is specified' do
+                # TODO: issue-644: multi-BEPool-LB: add unit tests for named-pool LBs
+                it 'adds the public IP to the specified pool'
+              end
+
+              context 'when an invalid backend_pool_name is specified' do
+                # TODO: issue-644: multi-BEPool-LB: add unit tests for named-pool LBs
+                it 'should raise an error'
+              end
+            end
+          end
+
+          context 'with multiple load_balancers' do
+            # TODO: issue-644: multi-LB: add unit tests for multi-LBs
+            it 'adds the public IP to each load_balancer'
+
+            context 'when backend_pool_name is specified' do
+              # TODO: issue-644: multi-BEPool-LB: add unit tests for named-pool LBs
+              it 'adds the public IP to the specified pool of each load_balancer'
+            end
+          end
+
           context 'with single application_gateway' do
             context 'when application_gateway has multiple backend pools' do
               # TODO: issue-644: multi-BEPool-AGW: add unit tests for multi-pool AGWs

src/bosh_azure_cpi/spec/unit/vm_manager/create/shared_stuff.rb

@@ -111,7 +111,15 @@
   end
   let(:load_balancer) do
     {
-      name: 'fake-lb-name'
+      name: 'fake-lb-name',
+      backend_address_pools: [
+        {
+          name: 'fake-pool-name',
+          id: 'fake-pool-id',
+          provisioning_state: 'fake-pool-state',
+          backend_ip_configurations: []
+        }
+      ]
     }
   end
   let(:application_gateway) do