Ansible Dynamic Inventory via SMD

This is an Ansible plugin which implements dynamic inventory, by integrating with smd (which maintains its own list of nodes and their states). As a result, the the need to explicitly maintain an Ansible inventory is removed, and smd becomes the relevant source of truth.

Demo

A traditional call to the smd API, via curl:

$ curl -s 'https://localhost:27779/hsm/v2/State/Components?type=Node&role=Compute&state=Ready' | jq
{
  "Components": [
    {
      "ID": "x1000c1s7b8n0",
      "Type": "Node",
      "State": "Ready",
      "Flag": "OK",
      "Enabled": true,
      "Role": "Compute",
      "NID": 9,
      "Arch": "X86"
    },
    ...
    {
      "ID": "x1000c1s7b1n0",
      "Type": "Node",
      "State": "Ready",
      "Flag": "OK",
      "Enabled": true,
      "Role": "Compute",
      "NID": 2,
      "Arch": "X86"
    }
  ]
}

Exposing smd components as native Ansible inventory, via this plugin:

$ ansible-inventory --graph -i smd_plugin_inventory.yml -v
...
Using inventory plugin 'smd_inventory' to process inventory source '/home/lritzdorf/smd_plugin_inventory.yml'
Parsed smd component filters {'type': 'Node', 'role': 'Compute', 'state': 'Ready'}
Access token loaded from $ACCESS_TOKEN
Retrieving inventory from smd...
smd component query returned 8 components
smd membership query returned 8 components
Flattened membership to 0 partitions, 0 groups
Populating Ansible inventory...
@all:
  |--@ungrouped:
  |  |--nid009
  |  |--nid008
  |  |--nid007
  |  |--nid006
  |  |--nid005
  |  |--nid004
  |  |--nid003
  |  |--nid002

Features

During inventory creation, additional data from smd is exposed to Ansible for possible use in playbooks and the like.

Partitions and Groups

Component partitions and groups from smd are exposed as Ansible host groups. Ansible groups corresponding to smd partitions are prefixed with prt_, while Ansible groups corresponding to smd groups are prefixed with grp_.

The following inventory was created from an smd instance with partitions p1 and p2, and groups squares, rectangles, and circles:

$ ansible-inventory --graph -i smd_plugin_inventory.yml
@all:
  |--@ungrouped:
  |--@prt_p2:
  |  |--nid009
  |  |--nid008
  |  |--nid007
  |  |--nid006
  |--@prt_p1:
  |  |--nid005
  |  |--nid004
  |  |--nid003
  |  |--nid002
  |--@grp_squares:
  |  |--nid007
  |  |--nid006
  |--@grp_circles:
  |  |--nid009
  |--@grp_rectangles:
  |  |--nid008
  |  |--nid007
  |  |--nid006

smd Component Data

Each node's smd component, along with its partition/group memberships, is stored under the smd_component host variable:

$ ansible-inventory --list -i smd_plugin_inventory.yml
{
    "_meta": {
        "hostvars": {
            "nid002": {
                "smd_component": {
                    "Arch": "X86",
                    "Enabled": true,
                    "Flag": "OK",
                    "ID": "x1000c1s7b1n0",
                    "NID": 2,
                    "Role": "Compute",
                    "State": "Ready",
                    "Type": "Node",
                    "groupLabels": [],
                    "id": "x1000c1s7b1n0",
                    "partitionName": "p1"
                }
            },
            "nid003": {
                "smd_component": {
                    "Arch": "X86",
                    "Enabled": true,
                    "Flag": "OK",
                    "ID": "x1000c1s7b2n0",
                    "NID": 3,
                    "Role": "Compute",
                    "State": "Ready",
                    "Type": "Node",
                    "groupLabels": [],
                    "id": "x1000c1s7b2n0",
                    "partitionName": "p1"
                }
            },
            ...

Example Inventory

The following inventory file was used to create the examples above:

---
plugin: smd_inventory
hsm_url: http://localhost:27779
#filter_by: "{'type': 'Node', 'role': 'Compute', 'state': 'Ready'}"
#access_token_envvar: ACCESS_TOKEN
nid_length: 3

Commented lines are default values, and will be auto-populated by Ansible if omitted.

Installation

This plugin can be installed locally by copying the main Python script (smd_inventory.py) into one of the following directories:

• The system-wide inventory plugin path (found via ansible-config dump | grep INVENTORY_PLUGIN_PATH)
• The relevant user's inventory plugin path (also found via ansible-config dump | grep INVENTORY_PLUGIN_PATH; usually inside of ~/.ansible/)
• An alternate plugin directory, defined by your Ansible configuration (see the relevant Ansible docs for details)