rst/scenario_guides/guide_rax.rst

Rackspace Cloud Guide
=====================

.. _rax_introduction:

Introduction
````````````

.. note:: This section of the documentation is under construction. We are in the process of adding more examples about the Rackspace modules and how they work together.  Once complete, there will also be examples for Rackspace Cloud in `ansible-examples <https://github.com/ansible/ansible-examples/>`_.

Ansible contains a number of core modules for interacting with Rackspace Cloud.

The purpose of this section is to explain how to put Ansible modules together
(and use inventory scripts) to use Ansible in a Rackspace Cloud context.

Prerequisites for using the rax modules are minimal.  In addition to ansible itself,
all of the modules require and are tested against pyrax 1.5 or higher.
You'll need this Python module installed on the execution host.

``pyrax`` is not currently available in many operating system
package repositories, so you will likely need to install it via pip:

.. code-block:: bash

    $ pip install pyrax

Ansible creates an implicit localhost that executes in the same context as the ``ansible-playbook`` and the other CLI tools.
If for any reason you need or want to have it in your inventory you should do something like the following:

.. code-block:: ini

    [localhost]
    localhost ansible_connection=local ansible_python_interpreter=/usr/local/bin/python2

For more information see :ref:`Implicit Localhost <implicit_localhost>`

In playbook steps, we'll typically be using the following pattern:

.. code-block:: yaml

    - hosts: localhost
      gather_facts: False
      tasks:

.. _credentials_file:

Credentials File
````````````````

The `rax.py` inventory script and all `rax` modules support a standard `pyrax` credentials file that looks like:

.. code-block:: ini

    [rackspace_cloud]
    username = myraxusername
    api_key = d41d8cd98f00b204e9800998ecf8427e

Setting the environment parameter ``RAX_CREDS_FILE`` to the path of this file will help Ansible find how to load
this information.

More information about this credentials file can be found at
https://github.com/pycontribs/pyrax/blob/master/docs/getting_started.md#authenticating


.. _virtual_environment:

Running from a Python Virtual Environment (Optional)
++++++++++++++++++++++++++++++++++++++++++++++++++++

Most users will not be using virtualenv, but some users, particularly Python developers sometimes like to.

There are special considerations when Ansible is installed to a Python virtualenv, rather than the default of installing at a global scope. Ansible assumes, unless otherwise instructed, that the python binary will live at /usr/bin/python.  This is done via the interpreter line in modules, however when instructed by setting the inventory variable 'ansible_python_interpreter', Ansible will use this specified path instead to find Python.  This can be a cause of confusion as one may assume that modules running on 'localhost', or perhaps running via 'local_action', are using the virtualenv Python interpreter.  By setting this line in the inventory, the modules will execute in the virtualenv interpreter and have available the virtualenv packages, specifically pyrax. If using virtualenv, you may wish to modify your localhost inventory definition to find this location as follows:

.. code-block:: ini

    [localhost]
    localhost ansible_connection=local ansible_python_interpreter=/path/to/ansible_venv/bin/python

.. note::

    pyrax may be installed in the global Python package scope or in a virtual environment.  There are no special considerations to keep in mind when installing pyrax.

.. _provisioning:

Provisioning
````````````

Now for the fun parts.

The 'rax' module provides the ability to provision instances within Rackspace Cloud.  Typically the provisioning task will be performed from your Ansible control server (in our example, localhost) against the Rackspace cloud API.  This is done for several reasons:

    - Avoiding installing the pyrax library on remote nodes
    - No need to encrypt and distribute credentials to remote nodes
    - Speed and simplicity

.. note::

   Authentication with the Rackspace-related modules is handled by either
   specifying your username and API key as environment variables or passing
   them as module arguments, or by specifying the location of a credentials
   file.

Here is a basic example of provisioning an instance in ad hoc mode:

.. code-block:: bash

    $ ansible localhost -m rax -a "name=awx flavor=4 image=ubuntu-1204-lts-precise-pangolin wait=yes"

Here's what it would look like in a playbook, assuming the parameters were defined in variables:

.. code-block:: yaml

    tasks:
      - name: Provision a set of instances
        rax:
            name: "{{ rax_name }}"
            flavor: "{{ rax_flavor }}"
            image: "{{ rax_image }}"
            count: "{{ rax_count }}"
            group: "{{ group }}"
            wait: yes
        register: rax
        delegate_to: localhost

The rax module returns data about the nodes it creates, like IP addresses, hostnames, and login passwords.  By registering the return value of the step, it is possible used this data to dynamically add the resulting hosts to inventory (temporarily, in memory). This facilitates performing configuration actions on the hosts in a follow-on task.  In the following example, the servers that were successfully created using the above task are dynamically added to a group called "raxhosts", with each nodes hostname, IP address, and root password being added to the inventory.

.. code-block:: yaml

    - name: Add the instances we created (by public IP) to the group 'raxhosts'
      add_host:
          hostname: "{{ item.name }}"
          ansible_host: "{{ item.rax_accessipv4 }}"
          ansible_password: "{{ item.rax_adminpass }}"
          groups: raxhosts
      loop: "{{ rax.success }}"
      when: rax.action == 'create'

With the host group now created, the next play in this playbook could now configure servers belonging to the raxhosts group.

.. code-block:: yaml

    - name: Configuration play
      hosts: raxhosts
      user: root
      roles:
        - ntp
        - webserver

The method above ties the configuration of a host with the provisioning step.  This isn't always what you want, and leads us
to the next section.

.. _host_inventory:

Host Inventory
``````````````

Once your nodes are spun up, you'll probably want to talk to them again.  The best way to handle this is to use the "rax" inventory plugin, which dynamically queries Rackspace Cloud and tells Ansible what nodes you have to manage.  You might want to use this even if you are spinning up cloud instances via other tools, including the Rackspace Cloud user interface. The inventory plugin can be used to group resources by metadata, region, OS, and so on.  Utilizing metadata is highly recommended in "rax" and can provide an easy way to sort between host groups and roles. If you don't want to use the ``rax.py`` dynamic inventory script, you could also still choose to manually manage your INI inventory file, though this is less recommended.

In Ansible it is quite possible to use multiple dynamic inventory plugins along with INI file data.  Just put them in a common directory and be sure the scripts are chmod +x, and the INI-based ones are not.

.. _raxpy:

rax.py
++++++

To use the Rackspace dynamic inventory script, copy ``rax.py`` into your inventory directory and make it executable. You can specify a credentials file for ``rax.py`` utilizing the ``RAX_CREDS_FILE`` environment variable.

.. note:: Dynamic inventory scripts (like ``rax.py``) are saved in ``/usr/local/share/py38-ansible/inventory`` if Ansible has been installed globally.  If installed to a virtualenv, the inventory scripts are installed to ``$VIRTUALENV/share/inventory``.

.. note:: Users of :ref:`ansible_platform` will note that dynamic inventory is natively supported by the controller in the platform, and all you have to do is associate a group with your Rackspace Cloud credentials, and it will easily synchronize without going through these steps::

    $ RAX_CREDS_FILE=~/.raxpub ansible all -i rax.py -m setup

``rax.py`` also accepts a ``RAX_REGION`` environment variable, which can contain an individual region, or a comma separated list of regions.

When using ``rax.py``, you will not have a 'localhost' defined in the inventory.

As mentioned previously, you will often be running most of these modules outside of the host loop, and will need 'localhost' defined.  The recommended way to do this, would be to create an ``inventory`` directory, and place both the ``rax.py`` script and a file containing ``localhost`` in it.

Executing ``ansible`` or ``ansible-playbook`` and specifying the ``inventory`` directory instead
of an individual file, will cause ansible to evaluate each file in that directory for inventory.

Let's test our inventory script to see if it can talk to Rackspace Cloud.

.. code-block:: bash

    $ RAX_CREDS_FILE=~/.raxpub ansible all -i inventory/ -m setup

Assuming things are properly configured, the ``rax.py`` inventory script will output information similar to the
following information, which will be utilized for inventory and variables.

.. code-block:: json

    {
        "ORD": [
            "test"
        ],
        "_meta": {
            "hostvars": {
                "test": {
                    "ansible_host": "198.51.100.1",
                    "rax_accessipv4": "198.51.100.1",
                    "rax_accessipv6": "2001:DB8::2342",
                    "rax_addresses": {
                        "private": [
                            {
                                "addr": "192.0.2.2",
                                "version": 4
                            }
                        ],
                        "public": [
                            {
                                "addr": "198.51.100.1",
                                "version": 4
                            },
                            {
                                "addr": "2001:DB8::2342",
                                "version": 6
                            }
                        ]
                    },
                    "rax_config_drive": "",
                    "rax_created": "2013-11-14T20:48:22Z",
                    "rax_flavor": {
                        "id": "performance1-1",
                        "links": [
                            {
                                "href": "https://ord.servers.api.rackspacecloud.com/111111/flavors/performance1-1",
                                "rel": "bookmark"
                            }
                        ]
                    },
                    "rax_hostid": "e7b6961a9bd943ee82b13816426f1563bfda6846aad84d52af45a4904660cde0",
                    "rax_human_id": "test",
                    "rax_id": "099a447b-a644-471f-87b9-a7f580eb0c2a",
                    "rax_image": {
                        "id": "b211c7bf-b5b4-4ede-a8de-a4368750c653",
                        "links": [
                            {
                                "href": "https://ord.servers.api.rackspacecloud.com/111111/images/b211c7bf-b5b4-4ede-a8de-a4368750c653",
                                "rel": "bookmark"
                            }
                        ]
                    },
                    "rax_key_name": null,
                    "rax_links": [
                        {
                            "href": "https://ord.servers.api.rackspacecloud.com/v2/111111/servers/099a447b-a644-471f-87b9-a7f580eb0c2a",
                            "rel": "self"
                        },
                        {
                            "href": "https://ord.servers.api.rackspacecloud.com/111111/servers/099a447b-a644-471f-87b9-a7f580eb0c2a",
                            "rel": "bookmark"
                        }
                    ],
                    "rax_metadata": {
                        "foo": "bar"
                    },
                    "rax_name": "test",
                    "rax_name_attr": "name",
                    "rax_networks": {
                        "private": [
                            "192.0.2.2"
                        ],
                        "public": [
                            "198.51.100.1",
                            "2001:DB8::2342"
                        ]
                    },
                    "rax_os-dcf_diskconfig": "AUTO",
                    "rax_os-ext-sts_power_state": 1,
                    "rax_os-ext-sts_task_state": null,
                    "rax_os-ext-sts_vm_state": "active",
                    "rax_progress": 100,
                    "rax_status": "ACTIVE",
                    "rax_tenant_id": "111111",
                    "rax_updated": "2013-11-14T20:49:27Z",
                    "rax_user_id": "22222"
                }
            }
        }
    }

.. _standard_inventory:

Standard Inventory
++++++++++++++++++

When utilizing a standard ini formatted inventory file (as opposed to the inventory plugin), it may still be advantageous to retrieve discoverable hostvar information  from the Rackspace API.

This can be achieved with the ``rax_facts`` module and an inventory file similar to the following:

.. code-block:: ini

    [test_servers]
    hostname1 rax_region=ORD
    hostname2 rax_region=ORD

.. code-block:: yaml

    - name: Gather info about servers
      hosts: test_servers
      gather_facts: False
      tasks:
        - name: Get facts about servers
          rax_facts:
            credentials: ~/.raxpub
            name: "{{ inventory_hostname }}"
            region: "{{ rax_region }}"
          delegate_to: localhost
        - name: Map some facts
          set_fact:
            ansible_host: "{{ rax_accessipv4 }}"

While you don't need to know how it works, it may be interesting to know what kind of variables are returned.

The ``rax_facts`` module provides facts as followings, which match the ``rax.py`` inventory script:

.. code-block:: json

    {
        "ansible_facts": {
            "rax_accessipv4": "198.51.100.1",
            "rax_accessipv6": "2001:DB8::2342",
            "rax_addresses": {
                "private": [
                    {
                        "addr": "192.0.2.2",
                        "version": 4
                    }
                ],
                "public": [
                    {
                        "addr": "198.51.100.1",
                        "version": 4
                    },
                    {
                        "addr": "2001:DB8::2342",
                        "version": 6
                    }
                ]
            },
            "rax_config_drive": "",
            "rax_created": "2013-11-14T20:48:22Z",
            "rax_flavor": {
                "id": "performance1-1",
                "links": [
                    {
                        "href": "https://ord.servers.api.rackspacecloud.com/111111/flavors/performance1-1",
                        "rel": "bookmark"
                    }
                ]
            },
            "rax_hostid": "e7b6961a9bd943ee82b13816426f1563bfda6846aad84d52af45a4904660cde0",
            "rax_human_id": "test",
            "rax_id": "099a447b-a644-471f-87b9-a7f580eb0c2a",
            "rax_image": {
                "id": "b211c7bf-b5b4-4ede-a8de-a4368750c653",
                "links": [
                    {
                        "href": "https://ord.servers.api.rackspacecloud.com/111111/images/b211c7bf-b5b4-4ede-a8de-a4368750c653",
                        "rel": "bookmark"
                    }
                ]
            },
            "rax_key_name": null,
            "rax_links": [
                {
                    "href": "https://ord.servers.api.rackspacecloud.com/v2/111111/servers/099a447b-a644-471f-87b9-a7f580eb0c2a",
                    "rel": "self"
                },
                {
                    "href": "https://ord.servers.api.rackspacecloud.com/111111/servers/099a447b-a644-471f-87b9-a7f580eb0c2a",
                    "rel": "bookmark"
                }
            ],
            "rax_metadata": {
                "foo": "bar"
            },
            "rax_name": "test",
            "rax_name_attr": "name",
            "rax_networks": {
                "private": [
                    "192.0.2.2"
                ],
                "public": [
                    "198.51.100.1",
                    "2001:DB8::2342"
                ]
            },
            "rax_os-dcf_diskconfig": "AUTO",
            "rax_os-ext-sts_power_state": 1,
            "rax_os-ext-sts_task_state": null,
            "rax_os-ext-sts_vm_state": "active",
            "rax_progress": 100,
            "rax_status": "ACTIVE",
            "rax_tenant_id": "111111",
            "rax_updated": "2013-11-14T20:49:27Z",
            "rax_user_id": "22222"
        },
        "changed": false
    }


Use Cases
`````````

This section covers some additional usage examples built around a specific use case.

.. _network_and_server:

Network and Server
++++++++++++++++++

Create an isolated cloud network and build a server

.. code-block:: yaml

    - name: Build Servers on an Isolated Network
      hosts: localhost
      gather_facts: False
      tasks:
        - name: Network create request
          rax_network:
            credentials: ~/.raxpub
            label: my-net
            cidr: 192.168.3.0/24
            region: IAD
            state: present
          delegate_to: localhost

        - name: Server create request
          rax:
            credentials: ~/.raxpub
            name: web%04d.example.org
            flavor: 2
            image: ubuntu-1204-lts-precise-pangolin
            disk_config: manual
            networks:
              - public
              - my-net
            region: IAD
            state: present
            count: 5
            exact_count: yes
            group: web
            wait: yes
            wait_timeout: 360
          register: rax
          delegate_to: localhost

.. _complete_environment:

Complete Environment
++++++++++++++++++++

Build a complete webserver environment with servers, custom networks and load balancers, install nginx and create a custom index.html

.. code-block:: yaml

    ---
    - name: Build environment
      hosts: localhost
      gather_facts: False
      tasks:
        - name: Load Balancer create request
          rax_clb:
            credentials: ~/.raxpub
            name: my-lb
            port: 80
            protocol: HTTP
            algorithm: ROUND_ROBIN
            type: PUBLIC
            timeout: 30
            region: IAD
            wait: yes
            state: present
            meta:
              app: my-cool-app
          register: clb

        - name: Network create request
          rax_network:
            credentials: ~/.raxpub
            label: my-net
            cidr: 192.168.3.0/24
            state: present
            region: IAD
          register: network

        - name: Server create request
          rax:
            credentials: ~/.raxpub
            name: web%04d.example.org
            flavor: performance1-1
            image: ubuntu-1204-lts-precise-pangolin
            disk_config: manual
            networks:
              - public
              - private
              - my-net
            region: IAD
            state: present
            count: 5
            exact_count: yes
            group: web
            wait: yes
          register: rax

        - name: Add servers to web host group
          add_host:
            hostname: "{{ item.name }}"
            ansible_host: "{{ item.rax_accessipv4 }}"
            ansible_password: "{{ item.rax_adminpass }}"
            ansible_user: root
            groups: web
          loop: "{{ rax.success }}"
          when: rax.action == 'create'

        - name: Add servers to Load balancer
          rax_clb_nodes:
            credentials: ~/.raxpub
            load_balancer_id: "{{ clb.balancer.id }}"
            address: "{{ item.rax_networks.private|first }}"
            port: 80
            condition: enabled
            type: primary
            wait: yes
            region: IAD
          loop: "{{ rax.success }}"
          when: rax.action == 'create'

    - name: Configure servers
      hosts: web
      handlers:
        - name: restart nginx
          service: name=nginx state=restarted

      tasks:
        - name: Install nginx
          apt: pkg=nginx state=latest update_cache=yes cache_valid_time=86400
          notify:
            - restart nginx

        - name: Ensure nginx starts on boot
          service: name=nginx state=started enabled=yes

        - name: Create custom index.html
          copy: content="{{ inventory_hostname }}" dest=/usr/share/nginx/www/index.html
                owner=root group=root mode=0644

.. _rackconnect_and_manged_cloud:

RackConnect and Managed Cloud
+++++++++++++++++++++++++++++

When using RackConnect version 2 or Rackspace Managed Cloud there are Rackspace automation tasks that are executed on the servers you create after they are successfully built. If your automation executes before the RackConnect or Managed Cloud automation, you can cause failures and unusable servers.

These examples show creating servers, and ensuring that the Rackspace automation has completed before Ansible continues onwards.

For simplicity, these examples are joined, however both are only needed when using RackConnect.  When only using Managed Cloud, the RackConnect portion can be ignored.

The RackConnect portions only apply to RackConnect version 2.

.. _using_a_control_machine:

Using a Control Machine
***********************

.. code-block:: yaml

    - name: Create an exact count of servers
      hosts: localhost
      gather_facts: False
      tasks:
        - name: Server build requests
          rax:
            credentials: ~/.raxpub
            name: web%03d.example.org
            flavor: performance1-1
            image: ubuntu-1204-lts-precise-pangolin
            disk_config: manual
            region: DFW
            state: present
            count: 1
            exact_count: yes
            group: web
            wait: yes
          register: rax

        - name: Add servers to in memory groups
          add_host:
            hostname: "{{ item.name }}"
            ansible_host: "{{ item.rax_accessipv4 }}"
            ansible_password: "{{ item.rax_adminpass }}"
            ansible_user: root
            rax_id: "{{ item.rax_id }}"
            groups: web,new_web
          loop: "{{ rax.success }}"
          when: rax.action == 'create'

    - name: Wait for rackconnect and managed cloud automation to complete
      hosts: new_web
      gather_facts: false
      tasks:
        - name: ensure we run all tasks from localhost
          delegate_to: localhost
          block:
            - name: Wait for rackconnnect automation to complete
              rax_facts:
                credentials: ~/.raxpub
                id: "{{ rax_id }}"
                region: DFW
              register: rax_facts
              until: rax_facts.ansible_facts['rax_metadata']['rackconnect_automation_status']|default('') == 'DEPLOYED'
              retries: 30
              delay: 10

            - name: Wait for managed cloud automation to complete
              rax_facts:
                credentials: ~/.raxpub
                id: "{{ rax_id }}"
                region: DFW
              register: rax_facts
              until: rax_facts.ansible_facts['rax_metadata']['rax_service_level_automation']|default('') == 'Complete'
              retries: 30
              delay: 10

    - name: Update new_web hosts with IP that RackConnect assigns
      hosts: new_web
      gather_facts: false
      tasks:
        - name: Get facts about servers
          rax_facts:
            name: "{{ inventory_hostname }}"
            region: DFW
          delegate_to: localhost
        - name: Map some facts
          set_fact:
            ansible_host: "{{ rax_accessipv4 }}"

    - name: Base Configure Servers
      hosts: web
      roles:
        - role: users

        - role: openssh
          opensshd_PermitRootLogin: "no"

        - role: ntp

.. _using_ansible_pull:

Using Ansible Pull
******************

.. code-block:: yaml

    ---
    - name: Ensure Rackconnect and Managed Cloud Automation is complete
      hosts: all
      tasks:
        - name: ensure we run all tasks from localhost
          delegate_to: localhost
          block:
            - name: Check for completed bootstrap
              stat:
                path: /etc/bootstrap_complete
              register: bootstrap

            - name: Get region
              command: xenstore-read vm-data/provider_data/region
              register: rax_region
              when: bootstrap.stat.exists != True

            - name: Wait for rackconnect automation to complete
              uri:
                url: "https://{{ rax_region.stdout|trim }}.api.rackconnect.rackspace.com/v1/automation_status?format=json"
                return_content: yes
              register: automation_status
              when: bootstrap.stat.exists != True
              until: automation_status['automation_status']|default('') == 'DEPLOYED'
              retries: 30
              delay: 10

            - name: Wait for managed cloud automation to complete
              wait_for:
                path: /tmp/rs_managed_cloud_automation_complete
                delay: 10
              when: bootstrap.stat.exists != True

            - name: Set bootstrap completed
              file:
                path: /etc/bootstrap_complete
                state: touch
                owner: root
                group: root
                mode: 0400

    - name: Base Configure Servers
      hosts: all
      roles:
        - role: users

        - role: openssh
          opensshd_PermitRootLogin: "no"

        - role: ntp

.. _using_ansible_pull_with_xenstore:

Using Ansible Pull with XenStore
********************************

.. code-block:: yaml

    ---
    - name: Ensure Rackconnect and Managed Cloud Automation is complete
      hosts: all
      tasks:
        - name: Check for completed bootstrap
          stat:
            path: /etc/bootstrap_complete
          register: bootstrap

        - name: Wait for rackconnect_automation_status xenstore key to exist
          command: xenstore-exists vm-data/user-metadata/rackconnect_automation_status
          register: rcas_exists
          when: bootstrap.stat.exists != True
          failed_when: rcas_exists.rc|int > 1
          until: rcas_exists.rc|int == 0
          retries: 30
          delay: 10

        - name: Wait for rackconnect automation to complete
          command: xenstore-read vm-data/user-metadata/rackconnect_automation_status
          register: rcas
          when: bootstrap.stat.exists != True
          until: rcas.stdout|replace('"', '') == 'DEPLOYED'
          retries: 30
          delay: 10

        - name: Wait for rax_service_level_automation xenstore key to exist
          command: xenstore-exists vm-data/user-metadata/rax_service_level_automation
          register: rsla_exists
          when: bootstrap.stat.exists != True
          failed_when: rsla_exists.rc|int > 1
          until: rsla_exists.rc|int == 0
          retries: 30
          delay: 10

        - name: Wait for managed cloud automation to complete
          command: xenstore-read vm-data/user-metadata/rackconnect_automation_status
          register: rsla
          when: bootstrap.stat.exists != True
          until: rsla.stdout|replace('"', '') == 'DEPLOYED'
          retries: 30
          delay: 10

        - name: Set bootstrap completed
          file:
            path: /etc/bootstrap_complete
            state: touch
            owner: root
            group: root
            mode: 0400

    - name: Base Configure Servers
      hosts: all
      roles:
        - role: users

        - role: openssh
          opensshd_PermitRootLogin: "no"

        - role: ntp

.. _advanced_usage:

Advanced Usage
``````````````

.. _awx_autoscale:

Autoscaling with AWX or Red Hat Ansible Automation Platform
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

The GUI component of :ref:`Red Hat Ansible Automation Platform <ansible_tower>` also contains a very nice feature for auto-scaling use cases.  In this mode, a simple curl script can call
a defined URL and the server will "dial out" to the requester and configure an instance that is spinning up.  This can be a great way
to reconfigure ephemeral nodes.  See `the documentation on provisioning callbacks <https://docs.ansible.com/ansible-tower/latest/html/userguide/job_templates.html#provisioning-callbacks>`_ for more details.

A benefit of using the callback approach over pull mode is that job results are still centrally recorded
and less information has to be shared with remote hosts.

.. _pending_information:

Orchestration in the Rackspace Cloud
++++++++++++++++++++++++++++++++++++

Ansible is a powerful orchestration tool, and rax modules allow you the opportunity to orchestrate complex tasks, deployments, and configurations.  The key here is to automate provisioning of infrastructure, like any other piece of software in an environment.  Complex deployments might have previously required manual manipulation of load balancers, or manual provisioning of servers.  Utilizing the rax modules included with Ansible, one can make the deployment of additional nodes contingent on the current number of running nodes, or the configuration of a clustered application dependent on the number of nodes with common metadata.  One could automate the following scenarios, for example:

* Servers that are removed from a Cloud Load Balancer one-by-one, updated, verified, and returned to the load balancer pool
* Expansion of an already-online environment, where nodes are provisioned, bootstrapped, configured, and software installed
* A procedure where app log files are uploaded to a central location, like Cloud Files, before a node is decommissioned
* Servers and load balancers that have DNS records created and destroyed on creation and decommissioning, respectively