Add Yorc documentation about hostspool placement policies

Author: stefbenoist

documentation/2.1.0/orchestrators/yorc/policies.html

@@ -26,14 +26,21 @@
           <h1 class="pull-left" style="margin-top: 0px;">Applying policies</h1>
           <a class="btn btn-primary pull-right" href="http://prose.io/#alien4cloud/alien4cloud.github.io/edit/sources/documentation/2.1.0/orchestrators/yorc/policies.markdown"><i class="fa fa-pencil-square-o"></i> Edit (pull request)</a>
         </div>
-        <p>Both monitoring policies (HTTP/TCP) and Affinity/Anti-Affinity OpenStack ServerGroup placement policies are natively available with Yorc Server.</p>
+        <p>Yorc provides natively the following policies:</p>
+
+<ul>
+  <li>Monitoring policies (HTTP/TCP).</li>
+  <li>Affinity/Anti-Affinity OpenStack ServerGroup placement policies.</li>
+  <li>Round-robin and bin-packing Hosts Pool placement policies.</li>
+</ul>
 
 <p>Let’s see how we can apply these on apps:</p>
 
 <ul>
   <li><a href="#applying-a-server-group-anti-affinity-placement-policy-on-openstack">Server Group Anti-affinity placement policy on OpenStack</a></li>
   <li><a href="#applying-tcp-monitoring-policy">TCP monitoring policy</a></li>
   <li><a href="#applying-http-monitoring-policy-on-a-web-application">HTTP monitoring policy</a></li>
+  <li><a href="#applying-hosts-pool-placement-policies">Round-robin and bin-packing Hosts pool placement policies</a></li>
 </ul>
 
 <h2 id="applying-a-server-group-anti-affinity-placement-policy-on-openstack">Applying a Server Group Anti affinity placement policy on OpenStack</h2>
@@ -195,6 +202,57 @@ <h3 id="edit-application-topology-2">Edit application topology</h3>
 
 <p>The next step will be to fix this by a self-healing policy !</p>
 
+<h2 id="applying-hosts-pool-placement-policies">Applying Hosts Pool Placement Policies</h2>
+
+<p>On a Hosts Pool location, you can provide hosts as Computes and specify if a host is shareable and so can be used by different applications or different Computes of the same application.</p>
+
+<p>Now, with placement policies applied on an application, you can define how to choose the good host candidate for your Compute.</p>
+
+<p>Two policies are available:</p>
+
+<ul>
+  <li><strong>yorc.policies.hostspool.BinPackingPlacement</strong></li>
+  <li><strong>yorc.policies.hostspool.RoundRobinPlacement</strong></li>
+</ul>
+
+<p><strong>BinPackingPlacement</strong> is the default policy if nothing is specified: It means the host with already the most related allocations will be elect preferentially.</p>
+
+<p>On the contrary, the <strong>round-robin placement</strong> policy allows to choose preferentially the host with the least related allocations.</p>
+
+<h3 id="configure-location-policies-3">Configure location policies</h3>
+
+<p>After configuring your HostsPool location as described previously click on the <img src="../../../../images/2.1.0/yorc/policies-button.png" alt="policies button" height="26px" class="inline" /> button, select <strong>Catalog</strong> and use the search to find <strong>policies.hostspool</strong> as below.</p>
+
+<p><img src="../../../../images/2.1.0/yorc/search-hostspool-policy.png" alt="Search hosts pool policies" /></p>
+
+<p>Next, drag-and-drop the <strong>BinPackingPlacement</strong> and the <strong>RoundRobinPlacement</strong> policies in the <strong>Policies</strong> resources list of your HostsPool location.</p>
+
+<p>You must finally have this configuration:</p>
+
+<p><img src="../../../../images/2.1.0/yorc/hostspool-policy-resource.png" alt="Configure your hosts pool policies" /></p>
+
+<p>Now, your hosts pool location is configured with placement policies !</p>
+
+<h3 id="edit-application-topology-3">Edit application topology</h3>
+
+<p>You can apply a Round-robin placement policy to your application topology by using an abstract policy: the <strong>tosca.policies.Placement</strong>.</p>
+
+<p>This allows to deploy your application on Hosts pool, as well as on GCP, if another specific placement policy is implemented for GCP too.</p>
+
+<p>Select your application and go to the <strong>Topology Editor</strong>. Click on the <img src="../../../../images/2.1.0/yorc/topology-policies-button.png" alt="policies button" height="52px" class="inline" /> button on the vertical blue bar on the left. Click on the <strong>+ Add policies</strong> button, search the abstract policy node <strong>Placement</strong> (tosca.policies.Placement) and drag-and-drop it on the policies list of your topology.</p>
+
+<p>Then you can select the <strong>Targets</strong> of the placement policy, i.e in this case, the node name of the compute on which will be applied the placement policy.</p>
+
+<p><img src="../../../../images/2.1.0/yorc/placement-abstract-topology-editor.png" alt="Add placement policy to your application topology" /></p>
+
+<h3 id="manage-current-deployment">Manage current deployment</h3>
+
+<p>Once you choose the <strong>hosts pool location</strong> for deploying your application, in case of multiple hostspool placement policies, you have to choose the one you want during the <strong>Policies Matching</strong> step.</p>
+
+<p><img src="../../../../images/2.1.0/yorc/hostspool-policies-matching.png" alt="Select your policy during policies matching step" /></p>
+
+<p>That’s it ! you can deploy your application: the Round-robin placement policy will be applied on the 2 instances of the Compute node.</p>
+
         <a class="btn btn-primary pull-right" href="http://prose.io/#alien4cloud/alien4cloud.github.io/edit/sources/documentation/2.1.0/orchestrators/yorc/policies.markdown"><i class="fa fa-pencil-square-o"></i> Edit (pull request)</a>
 	  </div>
     </div>