Provisioning of node-specific Hieradata

This guide assumes that your undercloud is already installed and ready to deploy an overcloud.

It is possible to provide some node-specific hieradata via Heat environment files and as such customize one or more settings for a specific node, regardless of the Heat ResourceGroup to which it belongs.

As a sample use case, we will distribute a node-specific disks configuration for a particular CephStorage node, which by default runs the ceph-osd service.

Collecting the node UUID

The node-specific hieradata is provisioned based on the node UUID, which is hardware dependent and immutable across reboots/reinstalls.

First make sure the introspection data is available for the target node, if it isn’t one may run introspection for a particular node as described in: Introspecting a Single Node. If the undercloud.conf does not have inspection_extras = true prior to undercloud installation/upgrade and introspection, then the machine unique UUID will not be in the Ironic database.

Then extract the machine unique UUID for the target node with a command like:

baremetal introspection data save NODE-ID | jq .extra.system.product.uuid | tr '[:upper:]' '[:lower:]'

where NODE-ID is the target node Ironic UUID. The value returned by the above command will be a unique and immutable machine UUID which isn’t related to the Ironic node UUID. For the next step, we’ll assume the output was 32e87b4c-c4a7-41be-865b-191684a6883b.

Creating the Heat environment file

Assuming we want to use /dev/sdc as a data disk for ceph-osd on our target node, we’ll create a yaml file, e.g. my-node-settings.yaml, with the following content depending on if either ceph-ansible (Pike and newer) or puppet-ceph (Ocata and older).

For ceph-ansible use:

  NodeDataLookup: {"32e87b4c-c4a7-41be-865b-191684a6883b": {"devices": ["/dev/sdc"]}}

For puppet-ceph use:

  OS::TripleO::CephStorageExtraConfigPre: /path/to/tripleo-heat-templates/puppet/extraconfig/pre_deploy/per_node.yaml

  NodeDataLookup: {"32e87b4c-c4a7-41be-865b-191684a6883b": {"ceph::profile::params::osds": {"/dev/sdc": {}}}}

In the above example we’re customizing only a single key for a single node, but the structure is that of a UUID-mapped hash so it is possible to customize multiple and different keys for multiple nodes.

Generating the Heat environment file for Ceph devices

The tools directory of tripleo-heat-templates (/usr/share/openstack-tripleo-heat-templates/tools/) contains a utility called which can be used to create a valid JSON Heat environment file automatically from Ironic’s introspection data.

Export the introspection data from Ironic for the Ceph nodes to be deployed:

baremetal introspection data save oc0-ceph-0 > ceph0.json
baremetal introspection data save oc0-ceph-1 > ceph1.json

Copy the utility to the stack user’s home directory on the undercloud and then use it to generate a node_data_lookup.json file which may be passed during openstack overcloud deployment:

./ -i ceph*.json -o node_data_lookup.json -k by_path

Pass the introspection data file from baremetal introspection data save for all nodes hosting Ceph OSDs to the utility as you may only define NodeDataLookup once during a deployment. The -i option can take an expression like *.json or a list of files as input.

The -k option defines the key of ironic disk data structure to use to identify the disk to be used as an OSD. Using name is not recommended as it will produce a file of devices like /dev/sdd which may not always point to the same device on reboot. Thus, by_path is recommended and is the default if -k is not specified.

Ironic will have one of the available disks on the system reserved as the root disk. The utility will always exclude the root disk from the list of devices generated.

Use ./ –help to see other available options.

Deploying with NodeDataLookup

Add the environment file described in the previous section to the deploy commandline:

openstack overcloud deploy [other overcloud deploy options] -e ~/my-node-settings.yaml


openstack overcloud deploy [other overcloud deploy options] -e ~/node_data_lookup.json

JSON is the recommended format (instead of JSON embedded in YAML) because you may use jq to validate the entire file before deployment.