Restructure playbooks for multiple commands

Much of the logic in the existing 'deploy' playbooks could be reused for
a teardown command, so it didn't make sense to duplicate this. Instead,
rename/restructure playbooks such that they refer to an area of
responsibility, rather than an action.

Also, make some changes to allow a new 'teardown' action.

README.md

@@ -41,15 +41,25 @@ required for different hosts, you will need to individually specify them: for a
 host with hostname *myhost*, set `physnet_mappings` within the file
 `ansible/host_vars/myhost`.
 
-### Deployment
+### Commands
 
-Currently, Tenks does not have a CLI or wrapper. A virtual cluster can be
-deployed by calling
-`ansible-playbook --inventory ansible/inventory ansible/deploy.yml --extra-vars=@override.yml`,
-where `override.yml` is the path to your override file. The `deploy.yml`
-playbook includes various constituent playbooks which perform different parts
-of the deployment. An individual section of Tenks can be run separately by
-substituting `ansible/deploy.yml` in the command above with the path to the
+Tenks has a variable `cmd` which specifies the command to be run. This variable
+can be set in your override file (see above). The possible values it can take
+are:
+
+* `deploy`: create a virtual cluster to the specification given. This is the
+  default command.
+* `teardown`: tear down any existing virtual cluster with the specification
+  given.
+
+### Running Tenks
+
+Currently, Tenks does not have a CLI or wrapper. It can be run by calling
+`ansible-playbook --inventory ansible/inventory ansible/run.yml --extra-vars=@override.yml`,
+where `override.yml` is the path to your override file. The `run.yml` playbook
+includes various constituent playbooks which perform different parts of the
+deployment. An individual section of Tenks can be run separately by
+substituting `ansible/run.yml` in the command above with the path to the
 playbook you want to run. The current playbooks can be seen in the Ansible
 structure diagram in the *Development* section.
 

ansible/deploy.yml

@@ -1,12 +0,0 @@
----
-- name: Perform deployment host configuration
-  import_playbook: deploy_hosts.yml
-
-- name: Perform deployment node configuration
-  import_playbook: deploy_nodes.yml
-
-- name: Enrol nodes in Ironic
-  import_playbook: enrol_nodes.yml
-
-- name: Register flavors in Nova
-  import_playbook: register_flavors.yml

ansible/deploy_hosts.yml

@@ -1,28 +0,0 @@
----
-- hosts: hypervisors
-  tasks:
-    - include_tasks: host_setup.yml
-
-- hosts: libvirt
-  tasks:
-    - name: Configure host for Libvirt
-      include_role:
-        name: stackhpc.libvirt-host
-      vars:
-        libvirt_host_pools:
-          - name: "{{ libvirt_pool_name }}"
-            type: "{{ libvirt_pool_type }}"
-            capacity: "{{ libvirt_pool_capacity }}"
-            path: "{{ libvirt_pool_path }}"
-            mode: "{{ libvirt_pool_mode }}"
-            owner: "{{ libvirt_pool_owner }}"
-            group: "{{ libvirt_pool_group }}"
-        libvirt_host_require_vt: "{{ libvirt_require_vt }}"
-
-    - name: Set up Virtual BMC daemon
-      include_role:
-        name: virtualbmc-daemon
-      vars:
-        vbmcd_virtualenv_path: "{{ virtualenv_path }}"
-        vbmcd_python_upper_constraints_url: >-
-          {{ python_upper_constraints_url }}

ansible/deploy_nodes.yml

@@ -1,12 +0,0 @@
----
-- name: Schedule nodes
-  import_playbook: schedule.yml
-
-- name: Set up node networking
-  import_playbook: node_networking.yml
-
-- name: Create nodes
-  import_playbook: create_nodes.yml
-
-- name: Set up virtual node BMCs
-  import_playbook: bmc.yml

ansible/host_setup.yml

@@ -1,45 +1,31 @@
 ---
-- name: Ensure general system requirements are installed
-  yum:
-    name: "{{ system_requirements }}"
-  become: true
+- hosts: hypervisors
+  tasks:
+    - include_tasks: hypervisor_setup.yml
 
-- name: Ensure log directory exists
-  file:
-    path: "{{ log_directory }}"
-    state: directory
-  become: true
+- hosts: libvirt
+  tasks:
+    - block:
+        - name: Configure host for Libvirt
+          include_role:
+            name: stackhpc.libvirt-host
+          vars:
+            libvirt_host_pools:
+              - name: "{{ libvirt_pool_name }}"
+                type: "{{ libvirt_pool_type }}"
+                capacity: "{{ libvirt_pool_capacity }}"
+                path: "{{ libvirt_pool_path }}"
+                mode: "{{ libvirt_pool_mode }}"
+                owner: "{{ libvirt_pool_owner }}"
+                group: "{{ libvirt_pool_group }}"
+            libvirt_host_require_vt: "{{ libvirt_require_vt }}"
 
-- name: Check if ovs-vsctl command is present
-  command: ovs-vsctl --version
-  register: ovs_vsctl_check
-  failed_when: false
-  changed_when: false
+        - name: Set up Virtual BMC daemon
+          include_role:
+            name: virtualbmc-daemon
+          vars:
+            vbmcd_virtualenv_path: "{{ virtualenv_path }}"
+            vbmcd_python_upper_constraints_url: >-
+              {{ python_upper_constraints_url }}
 
-- block:
-    - name: Ensure Open vSwitch package is installed
-      yum:
-        name: openvswitch
-      become: true
-
-    - name: Ensure Open vSwitch is started and enabled
-      service:
-        name: openvswitch
-        state: running
-        enabled: true
-      become: true
-  # Assume a non-zero return code means the command does not exist. Do this
-  # check to avoid installing Open vSwitch system-wide if the command already
-  # exists as a link to a containerised version of OVS.
-  when: ovs_vsctl_check.rc != 0
-
-- name: Configure physical networks
-  include_tasks: physical_network.yml
-  vars:
-    network_name: "{{ item.0 }}"
-    tenks_bridge: "{{ bridge_prefix ~ idx }}"
-    source_interface: "{{ item.1 }}"
-  # Sort to ensure we always enumerate in the same order.
-  loop: "{{ physnet_mappings | dictsort }}"
-  loop_control:
-    index_var: idx
+      when: cmd == 'deploy'

ansible/host_vars/localhost

@@ -1,4 +1,8 @@
 ---
+# The Tenks command to perform. 'deploy' will spin up a cluster to the given
+# specification; 'teardown' will tear it down.
+cmd: deploy
+
 # node_types is a dict that defines different sets of node specifications,
 # keyed by a 'node type name' to associate with each set of specifications. An
 # example of the format of this variable is below:

ansible/hypervisor_setup.yml

@@ -0,0 +1,51 @@
+---
+- name: Ensure general system requirements are installed
+  yum:
+    name: "{{ system_requirements }}"
+  become: true
+  # Don't uninstall requirements during teardown since they may already have
+  # been present.
+  when: cmd != 'teardown'
+
+- name: Ensure log directory exists
+  file:
+    path: "{{ log_directory }}"
+    state: directory
+  become: true
+  # Don't remove log directory during teardown to preserve historical logs.
+  when: cmd != 'teardown'
+
+- name: Check if ovs-vsctl command is present
+  command: ovs-vsctl --version
+  register: ovs_vsctl_check
+  failed_when: false
+  changed_when: false
+
+- block:
+    - name: Ensure Open vSwitch package is installed
+      yum:
+        name: openvswitch
+      become: true
+
+    - name: Ensure Open vSwitch is started and enabled
+      service:
+        name: openvswitch
+        state: running
+        enabled: true
+      become: true
+  # Assume a non-zero return code means the command does not exist. Do this
+  # check to avoid installing Open vSwitch system-wide if the command already
+  # exists as a link to a containerised version of OVS.
+  when: ovs_vsctl_check.rc != 0
+
+- name: Configure physical networks
+  include_tasks: physical_network.yml
+  vars:
+    network_name: "{{ item.0 }}"
+    tenks_bridge: "{{ bridge_prefix ~ idx }}"
+    source_interface: "{{ item.1 }}"
+    state: "{{ 'absent' if cmd == 'teardown' else 'present' }}"
+  # Sort to ensure we always enumerate in the same order.
+  loop: "{{ physnet_mappings | dictsort }}"
+  loop_control:
+    index_var: idx

ansible/node_bmc.yml

@@ -34,6 +34,7 @@
         vbmc_ipmi_port: "{{ ipmi_port_range_start + port_offset }}"
         vbmc_virtualenv_path: "{{ virtualenv_path }}"
         vbmc_log_directory: "{{ log_directory }}"
+        vbmc_state: "{{ 'absent' if cmd == 'teardown' else 'present' }}"
       loop: "{{ vbmc_nodes | map(attribute='name') | sort | list }}"
       loop_control:
         loop_var: domain

ansible/node_instantiation.yml

@@ -12,13 +12,19 @@
       {{ hostvars.localhost.allocations[inventory_hostname]
            | default([]) }}
   tasks:
-    - name: Create VM
+    - name: Configure VMs
       include_role:
         name: stackhpc.libvirt-vm
       vars:
         libvirt_vm_default_console_log_dir: "{{ log_directory }}"
         # Configure VM definitions for the Libvirt provider.
+        # FIXME(w-miller): Set absent/present in tenks_schedule on a per-node
+        # basis to account for existing allocations, rather than for all nodes
+        # here.
         libvirt_vms: >-
-          {{ nodes | map('set_libvirt_interfaces')
+          {{ nodes | map('combine',
+                         {'state': ('absent' if cmd == 'teardown'
+                                    else 'present')})
+                   | map('set_libvirt_interfaces')
                    | map('set_libvirt_volume_pool')
                    | list }}

ansible/node_networking.yml

@@ -11,13 +11,14 @@
       {{ hostvars.localhost.allocations[inventory_hostname]
            | default([]) }}
   tasks:
-    - name: Set up veth pairs for each node
+    - name: Configure veth pairs for each node
       include_role:
         name: veth-pair
       vars:
         veth_pair_ovs_bridge: "{{ item.1 | bridge_name }}"
         veth_pair_ovs_link_name: "{{ item.0 | ovs_link_name(item.1) }}"
         veth_pair_source_link_name: "{{ item.0 | source_link_name(item.1) }}"
+        state: "{{ 'absent' if cmd == 'teardown' else 'present' }}"
       # Loop over each physical network for each node allocated to this host.
       # Allocations are stored in localhost's vars.
       loop: >-

ansible/physical_network.yml

@@ -38,12 +38,13 @@
 
 
 ### Actual configuration starts here.
-- name: Ensure Open vSwitch bridge exists
+- name: Ensure Open vSwitch bridge is in the correct state
   openvswitch_bridge:
     bridge: "{{ tenks_bridge }}"
+    state: "{{ state }}"
   become: true
 
-- name: Connect to existing Linux bridge
+- name: Configure existing Linux bridge
   when: source_type == 'linux_bridge'
   include_role:
     name: veth-pair
@@ -54,12 +55,13 @@
     veth_pair_source_bridge: "{{ source_interface }}"
     veth_pair_source_link_name: >-
       {{ veth_prefix + tenks_bridge + veth_bridge_source_suffix }}
-    plug_into_source: true
+    veth_pair_plug_into_source: true
+    veth_pair_state: "{{ state }}"
 
-- name: Connect to existing Open vSwitch bridge
+- name: Configure existing Open vSwitch bridge
   when: source_type == 'ovs_bridge'
   block:
-    - name: Create patch port on Tenks bridge
+    - name: Configure patch port on Tenks bridge
       openvswitch_port:
         bridge: "{{ tenks_bridge }}"
         port: "{{ veth_prefix + tenks_bridge + veth_bridge_ovs_suffix }}"
@@ -70,6 +72,7 @@
             type=patch
             options:peer={{ veth_prefix + tenks_bridge +
                             veth_bridge_source_suffix }}
+        state: "{{ state }}"
       become: true
 
     - name: Create patch port on source bridge
@@ -81,11 +84,13 @@
             type=patch
             options:peer={{ veth_prefix + tenks_bridge +
                             veth_bridge_ovs_suffix }}
+        state: "{{ state }}"
       become: true
 
-- name: Plug source interface into Tenks bridge
+- name: Ensure source interface plugged state in Tenks bridge is correct
   when: source_type == 'direct'
   openvswitch_port:
     bridge: "{{ tenks_bridge }}"
     port: "{{ source_interface }}"
+    state: "{{ state }}"
   become: true

ansible/run.yml

@@ -0,0 +1,21 @@
+---
+- name: Perform deployment host configuration
+  import_playbook: host_setup.yml
+
+- name: Schedule nodes
+  import_playbook: schedule.yml
+
+- name: Configure node networking
+  import_playbook: node_networking.yml
+
+- name: Configure node instantiation
+  import_playbook: node_instantiation.yml
+
+- name: Set up virtual node BMCs
+  import_playbook: node_bmc.yml
+
+- name: Perform Ironic node configuration
+  import_playbook: node_enrolment.yml
+
+- name: Register flavors in Nova
+  import_playbook: flavor_registration.yml