Adding new example - upgrade ubuntu VM kernel

* Fixed some nits in README.rst

Change-Id: I6cc75ee033733c48745b935885c00918487435a2

examples/v2/openstack/README.rst

@@ -1,5 +1,5 @@
 ================================================
-OpenStack actions examples (based on v3 API/DSL)
+OpenStack actions examples (based on v2 API/DSL)
 ================================================
 
 These examples demonstrate how to use OpenStack Mistral actions in Mistral
@@ -92,3 +92,46 @@ To run the example:
 5. See the result of the workflow (virtual machine identifier)::
 
         mistral execution-get-output <execution_id>
+
+Update kernel
+-------------
+
+Workflow ``update_kernel`` located in file ``update_kernel.yaml`` demonstrates
+how to do some job on each VM in a tenant, particularly, how to upgrade VM kernel.
+Workflow can take either an array of **vm_ids** or all VMs in a tenant. Note that
+this workflow requires gateway VM with assigned floating IP which should be able to
+access to guest network in a tenant.
+
+**NOTE**: The workflow uses *std.ssh_proxied* action which requires existing private key
+file at executor host in **<home-user-directory>/.ssh/<private_key_filename>**
+**NOTE**: This upgrade kernel command works only for Ubuntu.
+
+To run the example:
+
+1. Load workflow from ``update_kernel.yaml``::
+
+        mistral workflow-create update_kernel.yaml
+
+2. Create ``input.json`` file containing workflow input parameters as follows::
+
+        {
+            "private_key_filename": "my_key.pem",
+            "gateway_host": "172.16.111.16",
+        }
+
+or::
+
+        {
+            "private_key_filename": "my_key.pem",
+            "gateway_host": "172.16.111.16",
+            "vm_ids": ["5486c382-fce3-4bde-abb3-51273a98c006", "7485f786-bcd1-8def-fed7-25637a89e600"]
+        }
+
+3. Start workflow::
+
+        mistral execution-create upgrade_kernel_on_vms input.json
+
+4. Using execution id from the previous step wait for completion (workflow ``SUCCESS`` state)::
+
+        mistral execution-get <execution_id>
+

examples/v2/openstack/update_kernel.yaml

@@ -0,0 +1,42 @@
+---
+version: '2.0'
+
+upgrade_kernel_on_vms:
+  input:
+    - private_key_filename
+    - gateway_host
+    - vm_ids: null
+    - username: ubuntu
+
+  tasks:
+    schedule_upgrade:
+      on-success:
+        - get_hosts: <% $.vm_ids != null %>
+        - get_vms: <% $.vm_ids = null %>
+
+    get_vms:
+      action: nova.servers_list
+      publish:
+        vm_ids: <% task(get_vms).result.id %>
+      keep-result: false
+      on-success:
+        - get_hosts
+
+    get_hosts:
+      with-items: id in <% $.vm_ids %>
+      action: nova.servers_get server=<% $.id %>
+      publish:
+        hosts: <% task(get_hosts).result.select({ip => $.addresses.get($.addresses.keys().first()).where($.get("OS-EXT-IPS:type") = fixed).first().addr}).ip %>
+      keep-result: false
+      on-success:
+        - upgrade_vm
+
+    upgrade_vm: # Works for ubuntu
+      with-items: host in <% $.hosts %>
+      action: std.ssh_proxied
+      input:
+        host: <% $.host %>
+        gateway_host: <% $.gateway_host %>
+        private_key_filename: <% $.private_key_filename %>
+        username: <% $.username %>
+        cmd: "sudo apt-get update && sudo apt-get install linux-image-generic-lts-$(lsb_release -sc) -y"