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.
The 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.
Overview¶
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.
A separate 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.
Features¶
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
heartbeat
endpoint.
However, the driver is currently synchronous, so only the first heartbeat is
processed and is used as a signal to start ansible-playbook
process.
User images¶
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,
the node’s disk_label
capability is honored if set in node’s
instance_info
(see also Choosing the disk label).
Configdrive partition¶
Creating a configdrive partition is supported for both whole disk
and partition images, on both msdos
and 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
part of ansible_devices
fact is used as root device to create partitions
on or write the whole disk image to.
Node cleaning¶
Cleaning is supported, both automated and manual. The driver has two default clean steps:
wiping device metadata
disk shredding
Their priority can be overridden via
[deploy]\erase_devices_metadata_priority
and
[deploy]\erase_devices_priority
options, respectively, in the ironic
configuration file.
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.
Note
Aborting cleaning steps is not supported.
Logging¶
Logging is implemented as custom Ansible callback module,
that makes use of oslo.log
and oslo.config
libraries
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.
Requirements¶
- Ansible
Tested with, and targets, Ansible 2.5.x
Bootstrap image requirements¶
password-less sudo permissions for the user used by Ansible
python 2.7.x
openssh-server
GNU coreutils
utils-linux
parted
gdisk
qemu-utils
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
and tinyipa
ramdisk, and an element for diskimage-builder
can be found
in ironic-staging-drivers project but will be eventually migrated to the new
ironic-python-agent-builder project.
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
ironic/driver-requirements.txt
fileEdit ironic configuration file
Add
ansible
to the list of deploy interfaces defined in[DEFAULT]\enabled_deploy_interfaces
option.Ensure that a hardware type supporting
ansible
deploy interface is enabled in[DEFAULT]\enabled_hardware_types
option.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.
Ansible-deploy options¶
Configuration file¶
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,
for example:
baremetal node set <node> \
--deploy-interface ansible \
--driver-info ansible_username=stack \
--driver-info ansible_key_file=/etc/ironic/id_rsa
- ansible_username
User name to use for Ansible to access the node. Default is taken from
[ansible]/default_username
option of the ironic configuration file (defaults toansible
).- ansible_key_file
Private SSH key used to access the node. Default is taken from
[ansible]/default_key_file
option of the ironic configuration file. If neither is set, the default private SSH keys of the user running theironic-conductor
process will be used.- ansible_deploy_playbook
Playbook to use when deploying this node. Default is taken from
[ansible]/default_deploy_playbook
option of the ironic configuration file (defaults todeploy.yaml
).- ansible_shutdown_playbook
Playbook to use to gracefully shutdown the node in-band. Default is taken from
[ansible]/default_shutdown_playbook
option of the ironic configuration file (defaults toshutdown.yaml
).- ansible_clean_playbook
Playbook to use when cleaning the node. Default is taken from
[ansible]/default_clean_playbook
option of the ironic configuration file (defaults toclean.yaml
).- ansible_clean_steps_config
Auxiliary YAML file that holds description of cleaning steps used by this node, and defines playbook tags in
ansible_clean_playbook
file corresponding to each cleaning step. Default is taken from[ansible]/default_clean_steps_config
option of the ironic configuration file (defaults toclean_steps.yaml
).- ansible_python_interpreter
Absolute path to the python interpreter on the managed machine. Default is taken from
[ansible]/default_python_interpreter
option of the ironic configuration file. Ansible uses/usr/bin/python
by default.
Customizing the deployment logic¶
Expected playbooks directory layout¶
The [ansible]\playbooks_path
option in the ironic configuration file
is expected to have a standard layout for an Ansible project with
some additions:
<playbooks_path>
|
\_ inventory
\_ add-ironic-nodes.yaml
\_ roles
\_ role1
\_ role2
\_ ...
|
\_callback_plugins
\_ ...
|
\_ library
\_ ...
The extra files relied by this driver are:
- inventory
Ansible inventory file containing a single entry of
conductor ansible_connection=local
. This basically defines an alias tolocalhost
. 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 abouthosts
file being empty.- add-ironic-nodes.yaml
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.
The default deploy.yaml
playbook is using several smaller roles that
correspond to particular stages of deployment process:
discover
- e.g. set root device and image targetprepare
- if needed, prepare system, for example create partitionsdeploy
- download/convert/write user image and configdriveconfigure
- post-deployment steps, e.g. installing the bootloader
Some more included roles are:
shutdown
- used to gracefully power the node off in-bandclean
- defines cleaning procedure, with each clean step defined as separate playbook tag.
Extending playbooks¶
Most probably you’d start experimenting like this:
Create a copy of
deploy.yaml
playbook in the same folder, name it distinctively.Create Ansible roles with your customized logic in
roles
folder.In your custom deploy playbook, replace the
prepare
role 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, likeironic_partitions
orironic_root_device
, and create custom partitions or (software) RAIDs.In your custom deploy playbook, replace the
configure
role 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
driver_info/ansible_deploy_playbook
field.Run deployment.
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):
ironic:
nodes:
- ip: "<IPADDRESS>"
name: "<NODE_UUID>"
user: "<USER ANSIBLE WILL USE>"
extra: "<COPY OF NODE's EXTRA FIELD>"
image:
url: "<URL TO FETCH THE USER IMAGE FROM>"
disk_format: "<qcow2|raw|...>"
container_format: "<bare|...>"
checksum: "<hash-algo:hashstring>"
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>"
configdrive:
type: "<url|file>"
location: "<URL OR PATH ON CONDUCTOR>"
partition_info:
label: "<msdos|gpt>"
preserve_ephemeral: "<bool>"
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>"
ironic.nodes
List of dictionaries (currently of only one element) that will be used by
add-ironic-nodes.yaml
play to populate in-memory inventory. It also contains a copy of node’sextra
field so you can access it in the playbooks. The Ansible’s host is set to node’s UUID.ironic.image
All fields of node’s
instance_info
that start withimage_
are passed inside this variable. Some extra notes and fields:mem_req
is calculated from image size (if available) and config option[ansible]extra_memory
.if
checksum
is not in the form<hash-algo>:<hash-sum>
, hashing algorithm is assumed to bemd5
(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_insecure
option in ironic configuration file.cafile
- custom CA bundle to use for validating image store SSL certificate. Takes value of[ansible]image_store_cafile
if 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_certfile
option 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_keyfile
option if defined. Currently is not used by default playbooks, however you can use this value in your custom playbooks.
ironic.partition_info.partitions
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
root_gb
,swap_mb
andephemeral_gb
fields ofinstance_info
. The driver will also prepend thebios_grub
-labeled partition when deploying on GPT-labeled disk, and pre-create a 64 MiB partition for configdrive if it is set ininstance_info
.Please read the documentation included in the
ironic_parted
module’s source for more info on the module and its arguments.ironic.partition_info.ephemeral_format
Optional. Taken from
instance_info
, it defines file system to be created on the ephemeral partition. Defaults to the value of[pxe]\default_ephemeral_format
option in ironic configuration file.ironic.partition_info.preserve_ephemeral
Optional. Taken from the
instance_info
, it specifies if the ephemeral partition must be preserved or rebuilt. Defaults tono
.ironic.raid_config
Taken from the
target_raid_config
if not empty, it specifies the RAID configuration to apply.
As usual for Ansible playbooks, you also have access to standard
Ansible facts discovered by setup
module.
Included custom Ansible modules¶
The provided playbooks_path/library
folder includes several custom
Ansible modules used by default implementation of deploy
and
prepare
roles.
You can use these modules in your playbooks as well.
stream_url
Streaming download from HTTP(S) source to the disk device directly, tries to be compatible with Ansible’s
get_url
module in terms of module arguments. Due to the low level of such operation it is not idempotent.ironic_parted
creates partition tables and partitions with
parted
utility. 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 theparted
module included in Ansible is not shadowed.