Ansible deploy interface¶
Ansible is a mature and popular automation tool, written in Python and requiring no agents running on the node being configured. All communications with the node are by default performed over secure SSH transport.
ansible deploy interface uses Ansible playbooks to define the
deployment logic. It is not based on
Ironic Python Agent (IPA)
and does not generally need IPA to be running in the deploy ramdisk.
The main advantage of this deploy interface is extended flexibility in regards to changing and adapting node deployment logic for specific use cases, via Ansible tooling that is already familiar to operators.
It can be used to shorten the usual feature development cycle of
implementing logic in ironic,
implementing logic in IPA,
rebuilding deploy ramdisk,
uploading deploy ramdisk to Glance/HTTP storage,
reassigning deploy ramdisk to nodes,
restarting ironic-conductor service(s) and
running a test deployment
by using a “stable” deploy ramdisk and not requiring ironic-conductor restarts (see Extending playbooks).
The main disadvantage of this deploy interface is the synchronous manner
of performing deployment/cleaning tasks.
ansible-playbook process is spawned for each node being
provisioned or cleaned, which consumes one thread from the thread pool
available to the
ironic-conductor process and blocks this thread until
the node provisioning or cleaning step is finished or fails.
This has to be taken into account when planning an ironic deployment
that enables this deploy interface.
Each action (deploy, clean) is described by a single playbook with roles, which is run whole during deployment, or tag-wise during cleaning. Control of cleaning steps is through tags and auxiliary clean steps file. The playbooks for actions can be set per-node, as can the clean steps file.
Similar to deploy interfaces relying on
Ironic Python Agent (IPA), this deploy
interface also depends on the deploy ramdisk calling back to ironic API’s
However, the driver is currently synchronous, so only the first heartbeat is
processed and is used as a signal to start
Supports whole-disk images and partition images:
compressed images are downloaded to RAM and converted to disk device;
raw images are streamed to disk directly.
For partition images the driver will create root partition, and,
if requested, ephemeral and swap partitions as set in node’s
instance_info by the Compute service or operator.
The create partition table will be of
msdos type by default,
disk_label capability is honored if set in node’s
instance_info (see also Choosing the disk label).
Creating a configdrive partition is supported for both whole disk
and partition images, on both
GPT labeled disks.
Root device hints¶
Root device hints are currently supported in their basic form only,
with exact matches (see Specifying the disk for deployment (root device hints) for more details).
If no root device hint is provided for the node, the first device returned as
ansible_devices fact is used as root device to create partitions
on or write the whole disk image to.
Cleaning is supported, both automated and manual. The driver has two default clean steps:
wiping device metadata
Their priority can be overridden via
[deploy]\erase_devices_priority options, respectively, in the ironic
As in the case of this driver all cleaning steps are known to the ironic-conductor service, booting the deploy ramdisk is completely skipped when there are no cleaning steps to perform.
Aborting cleaning steps is not supported.
Logging is implemented as custom Ansible callback module,
that makes use of
and can re-use logging configuration defined in the main ironic configuration
file to set logging for Ansible events, or use a separate file for this purpose.
It works best when
journald support for logging is enabled.
Tested with, and targets, Ansible 2.5.x
Bootstrap image requirements¶
password-less sudo permissions for the user used by Ansible
python-requests (for ironic callback and streaming image download)
python-netifaces (for ironic callback)
A set of scripts to build a suitable deploy ramdisk based on TinyCore Linux
tinyipa ramdisk, and an element for
diskimage-builder can be found
in ironic-staging-drivers project but will be eventually migrated to the new
Setting up your environment¶
Install ironic (either as part of OpenStack or standalone)
If using ironic as part of OpenStack, ensure that the Image service is configured to use the Object Storage service as backend, and the Bare Metal service is configured accordingly, see Configure the Image service for temporary URLs.
Install Ansible version as specified in
Edit ironic configuration file
ansibleto the list of deploy interfaces defined in
Ensure that a hardware type supporting
ansibledeploy interface is enabled in
Modify options in the
[ansible]section of ironic’s configuration file if needed (see Configuration file).
(Re)start ironic-conductor service
Build suitable deploy kernel and ramdisk images
Upload them to Glance or put in your HTTP storage
Create new or update existing nodes to use the enabled driver of your choice and populate Driver properties for the Node when different from defaults.
Deploy the node as usual.
Driver options are configured in
[ansible] section of ironic
configuration file, for their descriptions and default values please see
configuration file sample.
Driver properties for the Node¶
Set them per-node via
baremetal node set command,
baremetal node set <node> \
--deploy-interface ansible \
--driver-info ansible_username=stack \
User name to use for Ansible to access the node. Default is taken from
[ansible]/default_usernameoption of the ironic configuration file (defaults to
Private SSH key used to access the node. Default is taken from
[ansible]/default_key_fileoption of the ironic configuration file. If neither is set, the default private SSH keys of the user running the
ironic-conductorprocess will be used.
Playbook to use when deploying this node. Default is taken from
[ansible]/default_deploy_playbookoption of the ironic configuration file (defaults to
Playbook to use to gracefully shutdown the node in-band. Default is taken from
[ansible]/default_shutdown_playbookoption of the ironic configuration file (defaults to
Playbook to use when cleaning the node. Default is taken from
[ansible]/default_clean_playbookoption of the ironic configuration file (defaults to
Auxiliary YAML file that holds description of cleaning steps used by this node, and defines playbook tags in
ansible_clean_playbookfile corresponding to each cleaning step. Default is taken from
[ansible]/default_clean_steps_configoption of the ironic configuration file (defaults to
Absolute path to the python interpreter on the managed machine. Default is taken from
[ansible]/default_python_interpreteroption of the ironic configuration file. Ansible uses
Customizing the deployment logic¶
Expected playbooks directory layout¶
[ansible]\playbooks_path option in the ironic configuration file
is expected to have a standard layout for an Ansible project with
The extra files relied by this driver are:
Ansible inventory file containing a single entry of
conductor ansible_connection=local. This basically defines an alias to
localhost. Its purpose is to make logging for tasks performed by Ansible locally and referencing the localhost in playbooks more intuitive. This also suppresses warnings produced by Ansible about
hostsfile being empty.
This file contains an Ansible play that populates in-memory Ansible inventory with access information received from the ansible-deploy interface, as well as some per-node variables. Include it in all your custom playbooks as the first play.
deploy.yaml playbook is using several smaller roles that
correspond to particular stages of deployment process:
discover- e.g. set root device and image target
prepare- if needed, prepare system, for example create partitions
deploy- download/convert/write user image and configdrive
configure- post-deployment steps, e.g. installing the bootloader
Some more included roles are:
shutdown- used to gracefully power the node off in-band
clean- defines cleaning procedure, with each clean step defined as separate playbook tag.
Most probably you’d start experimenting like this:
Create a copy of
deploy.yamlplaybook in the same folder, name it distinctively.
Create Ansible roles with your customized logic in
In your custom deploy playbook, replace the
preparerole with your own one that defines steps to be run before image download/writing. This is a good place to set facts overriding those provided/omitted by the driver, like
ironic_root_device, and create custom partitions or (software) RAIDs.
In your custom deploy playbook, replace the
configurerole with your own one that defines steps to be run after image is written to disk. This is a good place for example to configure the bootloader and add kernel options to avoid additional reboots.
Use those new roles in your new playbook.
Assign the custom deploy playbook you’ve created to the node’s
No ironic-conductor restart is necessary.
A new deploy ramdisk must be built and assigned to nodes only when you want to use a command/script/package not present in the current deploy ramdisk and you can not or do not want to install those at runtime.
Variables you have access to¶
This driver will pass the single JSON-ified extra var argument to
Ansible (as in
ansible-playbook -e ..).
Those values are then accessible in your plays as well
(some of them are optional and might not be defined):
- ip: "<IPADDRESS>"
user: "<USER ANSIBLE WILL USE>"
extra: "<COPY OF NODE's EXTRA FIELD>"
url: "<URL TO FETCH THE USER IMAGE FROM>"
mem_req: "<REQUIRED FREE MEMORY TO DOWNLOAD IMAGE TO RAM>"
tags: "<LIST OF IMAGE TAGS AS DEFINED IN GLANCE>"
properties: "<DICT OF IMAGE PROPERTIES AS DEFINED IN GLANCE>"
location: "<URL OR PATH ON CONDUCTOR>"
ephemeral_format: "<FILESYSTEM TO CREATE ON EPHEMERAL PARTITION>"
partitions: "<LIST OF PARTITIONS IN FORMAT EXPECTED BY PARTED MODULE>"
raid_config: "<COPY OF NODE's TARGET_RAID_CONFIG FIELD>"
List of dictionaries (currently of only one element) that will be used by
add-ironic-nodes.yamlplay to populate in-memory inventory. It also contains a copy of node’s
extrafield so you can access it in the playbooks. The Ansible’s host is set to node’s UUID.
All fields of node’s
instance_infothat start with
image_are passed inside this variable. Some extra notes and fields:
mem_reqis calculated from image size (if available) and config option
checksumis not in the form
<hash-algo>:<hash-sum>, hashing algorithm is assumed to be
md5(default in Glance).
validate_certs- boolean (
yes/no) flag that turns validating image store SSL certificate on or off (default is ‘yes’). Governed by
[ansible]image_store_insecureoption in ironic configuration file.
cafile- custom CA bundle to use for validating image store SSL certificate. Takes value of
[ansible]image_store_cafileif that is defined. Currently is not used by default playbooks, as Ansible has no way to specify the custom CA bundle to use for single HTTPS actions, however you can use this value in your custom playbooks to for example upload and register this CA in the ramdisk at deploy time.
client_cert- cert file for client-side SSL authentication. Takes value of
[ansible]image_store_certfileoption if defined. Currently is not used by default playbooks, however you can use this value in your custom playbooks.
client_key- private key file for client-side SSL authentication. Takes value of
[ansible]image_store_keyfileoption if defined. Currently is not used by default playbooks, however you can use this value in your custom playbooks.
Optional. List of dictionaries defining partitions to create on the node in the form:
partitions: - name: "<NAME OF PARTITION>" unit: "<UNITS FOR SIZE>" size: "<SIZE OF THE PARTITION>" type: "<primary|extended|logical>" align: "<ONE OF PARTED_SUPPORTED OPTIONS>" format: "<PARTITION TYPE TO SET>" flags: flag_name: "<bool>"
The driver will populate this list from
instance_info. The driver will also prepend the
bios_grub-labeled partition when deploying on GPT-labeled disk, and pre-create a 64 MiB partition for configdrive if it is set in
Please read the documentation included in the
ironic_partedmodule’s source for more info on the module and its arguments.
Optional. Taken from
instance_info, it defines file system to be created on the ephemeral partition. Defaults to the value of
[pxe]\default_ephemeral_formatoption in ironic configuration file.
Optional. Taken from the
instance_info, it specifies if the ephemeral partition must be preserved or rebuilt. Defaults to
Taken from the
target_raid_configif not empty, it specifies the RAID configuration to apply.
As usual for Ansible playbooks, you also have access to standard
Ansible facts discovered by
Included custom Ansible modules¶
playbooks_path/library folder includes several custom
Ansible modules used by default implementation of
You can use these modules in your playbooks as well.
Streaming download from HTTP(S) source to the disk device directly, tries to be compatible with Ansible’s
get_urlmodule in terms of module arguments. Due to the low level of such operation it is not idempotent.
creates partition tables and partitions with
partedutility. Due to the low level of such operation it is not idempotent. Please read the documentation included in the module’s source for more information about this module and its arguments. The name is chosen so that the
partedmodule included in Ansible is not shadowed.