nova.conf : can [pci]alias be multivalued ?
Hi, We need to support several GPU models in our Nova configuration. This normally requires to add multiple `alias` entries (lines) in the [pci] section of nova.conf. Unfortunately for us, it complicates a lot the generation of nova.conf by our system configuration management tool (where the section is represented by a dict/hash, meaning that there is only 1 possible entry for 'alias'). Before trying to hack our tool, we were wondering if there is a way to put the different values as a list for a single 'alias' line and what should be the separator or syntax ? I was not able to identify a generic description of the syntax for multivalued parameters, if there is a generic rule. I already found this limitation (but we could live with it) for Keystone [federation]trusted_dashboard for example... Thanks in advance for any hint. Best regards, Michel
On 6/6/25 13:08, Michel Jouvin wrote:
Hi,
We need to support several GPU models in our Nova configuration. This normally requires to add multiple `alias` entries (lines) in the [pci] section of nova.conf. Unfortunately for us, it complicates a lot the generation of nova.conf by our system configuration management tool (where the section is represented by a dict/hash, meaning that there is only 1 possible entry for 'alias'). Before trying to hack our tool, we were wondering if there is a way to put the different values as a list for a single 'alias' line and what should be the separator or syntax ?
I was not able to identify a generic description of the syntax for multivalued parameters, if there is a generic rule. I already found this limitation (but we could live with it) for Keystone [federation]trusted_dashboard for example...
Thanks in advance for any hint. Best regards,
Michel
As much as I know, you *must* define multiple times the alias directive. For example, in your nova-scheduler / nova-api / nova-conductor nodes (I believe it should be in your scheduler nodes, not sure if api and conductor needs that...) you must have something like this: alias={"vendor_id":"10de","product_id":"25b6","name":"nvidia-a2","device_type":"type-PF"} alias={"vendor_id":"10de","product_id":"27b8","name":"nvidia-l4","device_type":"type-PF"} to define aliases for Nvidia A2 and L4. This should match what you have it compute nodes, that may have the same alias directive. I hope this helps, Cheers, Thomas Goirand (zigo)
Hi Thomas, Thanks for your answer. We identified that it was the documented way to do it, my question was wether there was a one-line alternative. But I managed to find https://docs.openstack.org/mitaka/config-reference/config-format.html which is pretty old (does not seem to exist under latest) but is clear that a multi-valued parameter is different from a list in OpenStack and must be defined as a repeated paramter in the config file. So I'm afraid there is no one-line alternative.. Michel Le 06/06/2025 à 15:33, Thomas Goirand a écrit :
On 6/6/25 13:08, Michel Jouvin wrote:
Hi,
We need to support several GPU models in our Nova configuration. This normally requires to add multiple `alias` entries (lines) in the [pci] section of nova.conf. Unfortunately for us, it complicates a lot the generation of nova.conf by our system configuration management tool (where the section is represented by a dict/hash, meaning that there is only 1 possible entry for 'alias'). Before trying to hack our tool, we were wondering if there is a way to put the different values as a list for a single 'alias' line and what should be the separator or syntax ?
I was not able to identify a generic description of the syntax for multivalued parameters, if there is a generic rule. I already found this limitation (but we could live with it) for Keystone [federation]trusted_dashboard for example...
Thanks in advance for any hint. Best regards,
Michel
As much as I know, you *must* define multiple times the alias directive. For example, in your nova-scheduler / nova-api / nova-conductor nodes (I believe it should be in your scheduler nodes, not sure if api and conductor needs that...) you must have something like this:
alias={"vendor_id":"10de","product_id":"25b6","name":"nvidia-a2","device_type":"type-PF"}
alias={"vendor_id":"10de","product_id":"27b8","name":"nvidia-l4","device_type":"type-PF"}
to define aliases for Nvidia A2 and L4. This should match what you have it compute nodes, that may have the same alias directive.
I hope this helps, Cheers,
Thomas Goirand (zigo)
On 06/06/2025 15:12, Michel Jouvin wrote:
Hi Thomas,
Thanks for your answer. We identified that it was the documented way to do it, my question was wether there was a one-line alternative. But I managed to find https://docs.openstack.org/mitaka/config-reference/config-format.html which is pretty old (does not seem to exist under latest) but is clear that a multi-valued parameter is different from a list in OpenStack and must be defined as a repeated paramter in the config file. So I'm afraid there is no one-line alternative..
so yes this is a know issue the pci alise si defiend as a multi-valued https://docs.openstack.org/nova/latest/configuration/config.html#pci.alias a long time ago when https://docs.openstack.org/nova/latest/configuration/config.html#pci.device_... was stilll called pci_passthrough_whitelist we actully added suport for definign it as a json list on one line device_spec = [{"product_id":"0001", "vendor_id":"8086"}, {"product_id":"0002", "vendor_id":"8086"}] both the aliias and dev_secect value need to be valid json. it would not neessiarly be a lot of work to correct this gap and just supprot a list of json obejct for the alias as well we just never got around to it. there is no technial reason not to do that, its just that no one has wirttign the patch to do it. this is a somewhat trivial feature to add and i think it woudl fit in the scope of a specless blueprint i know it was intentionally not done when i twas doen for the pci_passthrough_whitelist but beyond limiting scope i dont recall the reason why both were not updated. so its not a bug but it is a painpoint for anyone who tryes to treat oslo.config files as ini files they are not and ini parser dont supprot multi-value filed
Michel
Le 06/06/2025 à 15:33, Thomas Goirand a écrit :
On 6/6/25 13:08, Michel Jouvin wrote:
Hi,
We need to support several GPU models in our Nova configuration. This normally requires to add multiple `alias` entries (lines) in the [pci] section of nova.conf. Unfortunately for us, it complicates a lot the generation of nova.conf by our system configuration management tool (where the section is represented by a dict/hash, meaning that there is only 1 possible entry for 'alias'). Before trying to hack our tool, we were wondering if there is a way to put the different values as a list for a single 'alias' line and what should be the separator or syntax ?
I was not able to identify a generic description of the syntax for multivalued parameters, if there is a generic rule. I already found this limitation (but we could live with it) for Keystone [federation]trusted_dashboard for example...
Thanks in advance for any hint. Best regards,
Michel
As much as I know, you *must* define multiple times the alias directive. For example, in your nova-scheduler / nova-api / nova-conductor nodes (I believe it should be in your scheduler nodes, not sure if api and conductor needs that...) you must have something like this:
alias={"vendor_id":"10de","product_id":"25b6","name":"nvidia-a2","device_type":"type-PF"}
alias={"vendor_id":"10de","product_id":"27b8","name":"nvidia-l4","device_type":"type-PF"}
to define aliases for Nvidia A2 and L4. This should match what you have it compute nodes, that may have the same alias directive.
I hope this helps, Cheers,
Thomas Goirand (zigo)
Hi Sean, Thanks for your answer and confirming it is something not optimal that could be improved without too much pain... Even if we have to leave with it in the short term if I understood correctly. Best regards, Michel Sent from my mobile Le 6 juin 2025 18:07:42 Sean Mooney <smooney@redhat.com> a écrit :
On 06/06/2025 15:12, Michel Jouvin wrote:
Hi Thomas,
Thanks for your answer. We identified that it was the documented way to do it, my question was wether there was a one-line alternative. But I managed to find https://docs.openstack.org/mitaka/config-reference/config-format.html which is pretty old (does not seem to exist under latest) but is clear that a multi-valued parameter is different from a list in OpenStack and must be defined as a repeated paramter in the config file. So I'm afraid there is no one-line alternative..
so yes this is a know issue
the pci alise si defiend as a multi-valued
https://docs.openstack.org/nova/latest/configuration/config.html#pci.alias
a long time ago when https://docs.openstack.org/nova/latest/configuration/config.html#pci.device_...
was stilll called pci_passthrough_whitelist
we actully added suport for definign it as a json list on one line
device_spec = [{"product_id":"0001", "vendor_id":"8086"}, {"product_id":"0002", "vendor_id":"8086"}]
both the aliias and dev_secect value need to be valid json.
it would not neessiarly be a lot of work to correct this gap and just supprot a list of json obejct for the alias as well we just never got around to it.
there is no technial reason not to do that, its just that no one has wirttign the patch to do it.
this is a somewhat trivial feature to add and i think it woudl fit in the scope of a specless blueprint
i know it was intentionally not done when i twas doen for the pci_passthrough_whitelist but beyond limiting scope i dont recall the reason why both were not updated. so its not a bug but it is a painpoint for anyone who tryes to treat oslo.config files as ini files they are not and ini parser dont supprot multi-value filed
Michel
Le 06/06/2025 à 15:33, Thomas Goirand a écrit :
On 6/6/25 13:08, Michel Jouvin wrote:
Hi,
We need to support several GPU models in our Nova configuration. This normally requires to add multiple `alias` entries (lines) in the [pci] section of nova.conf. Unfortunately for us, it complicates a lot the generation of nova.conf by our system configuration management tool (where the section is represented by a dict/hash, meaning that there is only 1 possible entry for 'alias'). Before trying to hack our tool, we were wondering if there is a way to put the different values as a list for a single 'alias' line and what should be the separator or syntax ?
I was not able to identify a generic description of the syntax for multivalued parameters, if there is a generic rule. I already found this limitation (but we could live with it) for Keystone [federation]trusted_dashboard for example...
Thanks in advance for any hint. Best regards,
Michel
As much as I know, you *must* define multiple times the alias directive. For example, in your nova-scheduler / nova-api / nova-conductor nodes (I believe it should be in your scheduler nodes, not sure if api and conductor needs that...) you must have something like this:
alias={"vendor_id":"10de","product_id":"25b6","name":"nvidia-a2","device_type":"type-PF"}
alias={"vendor_id":"10de","product_id":"27b8","name":"nvidia-l4","device_type":"type-PF"}
to define aliases for Nvidia A2 and L4. This should match what you have it compute nodes, that may have the same alias directive.
I hope this helps, Cheers,
Thomas Goirand (zigo)
Hi, I confirm that this works with JSON value, e.g. device_spec = [{"vendor_id": "10de", "product_id": "abcd"}, {"vendor_id": "10de", "product_id": "acdc"}] alias = [{"name": "custom", "vendor_id": "10de", "product_id": "abcd"}, {"name": "custom2", "vendor_id": "10de", "product_id": "acdc"}] And within ansible (if you are using ini_file): - name: configure nova (json config) ini_file: path: /etc/nova/nova.conf section: "{{item.section}}" option: "{{item.option}}" value: "{{item.value | to_json}}" with_items: - { section: "pci", option: "device_spec", value: [{vendor_id: "10de", product_id: "abcd"}, {vendor_id: "10de", product_id: "acdc"}] } - { section: "pci", option: "alias", value: [{name: "custom", vendor_id: "10de", product_id: "abcd"}, {name: "custom2", vendor_id: "10de", product_id: "acdc"}] } notify: - restart nova regards On 06.06.25 - 17:06, Sean Mooney wrote:
On 06/06/2025 15:12, Michel Jouvin wrote:
Hi Thomas,
Thanks for your answer. We identified that it was the documented way to do it, my question was wether there was a one-line alternative. But I managed to find https://docs.openstack.org/mitaka/config-reference/config-format.html which is pretty old (does not seem to exist under latest) but is clear that a multi-valued parameter is different from a list in OpenStack and must be defined as a repeated paramter in the config file. So I'm afraid there is no one-line alternative..
so yes this is a know issue
the pci alise si defiend as a multi-valued
https://docs.openstack.org/nova/latest/configuration/config.html#pci.alias
a long time ago when https://docs.openstack.org/nova/latest/configuration/config.html#pci.device_...
was stilll called pci_passthrough_whitelist
we actully added suport for definign it as a json list on one line
device_spec = [{"product_id":"0001", "vendor_id":"8086"}, {"product_id":"0002", "vendor_id":"8086"}]
both the aliias and dev_secect value need to be valid json.
it would not neessiarly be a lot of work to correct this gap and just supprot a list of json obejct for the alias as well we just never got around to it.
there is no technial reason not to do that, its just that no one has wirttign the patch to do it.
this is a somewhat trivial feature to add and i think it woudl fit in the scope of a specless blueprint
i know it was intentionally not done when i twas doen for the pci_passthrough_whitelist but beyond limiting scope i dont recall the reason why both were not updated. so its not a bug but it is a painpoint for anyone who tryes to treat oslo.config files as ini files they are not and ini parser dont supprot multi-value filed
Michel
Le 06/06/2025 à 15:33, Thomas Goirand a écrit :
On 6/6/25 13:08, Michel Jouvin wrote:
Hi,
We need to support several GPU models in our Nova configuration. This normally requires to add multiple `alias` entries (lines) in the [pci] section of nova.conf. Unfortunately for us, it complicates a lot the generation of nova.conf by our system configuration management tool (where the section is represented by a dict/hash, meaning that there is only 1 possible entry for 'alias'). Before trying to hack our tool, we were wondering if there is a way to put the different values as a list for a single 'alias' line and what should be the separator or syntax ?
I was not able to identify a generic description of the syntax for multivalued parameters, if there is a generic rule. I already found this limitation (but we could live with it) for Keystone [federation]trusted_dashboard for example...
Thanks in advance for any hint. Best regards,
Michel
As much as I know, you *must* define multiple times the alias directive. For example, in your nova-scheduler / nova-api / nova-conductor nodes (I believe it should be in your scheduler nodes, not sure if api and conductor needs that...) you must have something like this:
alias={"vendor_id":"10de","product_id":"25b6","name":"nvidia-a2","device_type":"type-PF"}
alias={"vendor_id":"10de","product_id":"27b8","name":"nvidia-l4","device_type":"type-PF"}
to define aliases for Nvidia A2 and L4. This should match what you have it compute nodes, that may have the same alias directive.
I hope this helps, Cheers,
Thomas Goirand (zigo)
On 10/06/2025 13:34, Arnaud Morin wrote:
Hi,
I confirm that this works with JSON value, e.g.
device_spec = [{"vendor_id": "10de", "product_id": "abcd"}, {"vendor_id": "10de", "product_id": "acdc"}] alias = [{"name": "custom", "vendor_id": "10de", "product_id": "abcd"}, {"name": "custom2", "vendor_id": "10de", "product_id": "acdc"}]
if alias works its by acident as we dont offically supprot that. it might work in some cases or as a an uninteded side effect of other changes we made so until we have docs and test to make sure it does not break be careful with that. on the pluse side if all that is need to "support" defining asias with json is docs, tests and a release note then that proably can be fixed as a bug and backported to whichever release this actully works for.
And within ansible (if you are using ini_file):
- name: configure nova (json config) ini_file: path: /etc/nova/nova.conf section: "{{item.section}}" option: "{{item.option}}" value: "{{item.value | to_json}}" with_items: - { section: "pci", option: "device_spec", value: [{vendor_id: "10de", product_id: "abcd"}, {vendor_id: "10de", product_id: "acdc"}] } - { section: "pci", option: "alias", value: [{name: "custom", vendor_id: "10de", product_id: "abcd"}, {name: "custom2", vendor_id: "10de", product_id: "acdc"}] } notify: - restart nova
regards
On 06.06.25 - 17:06, Sean Mooney wrote:
On 06/06/2025 15:12, Michel Jouvin wrote:
Hi Thomas,
Thanks for your answer. We identified that it was the documented way to do it, my question was wether there was a one-line alternative. But I managed to find https://docs.openstack.org/mitaka/config-reference/config-format.html which is pretty old (does not seem to exist under latest) but is clear that a multi-valued parameter is different from a list in OpenStack and must be defined as a repeated paramter in the config file. So I'm afraid there is no one-line alternative..
so yes this is a know issue
the pci alise si defiend as a multi-valued
https://docs.openstack.org/nova/latest/configuration/config.html#pci.alias
a long time ago when https://docs.openstack.org/nova/latest/configuration/config.html#pci.device_...
was stilll called pci_passthrough_whitelist
we actully added suport for definign it as a json list on one line
device_spec = [{"product_id":"0001", "vendor_id":"8086"}, {"product_id":"0002", "vendor_id":"8086"}]
both the aliias and dev_secect value need to be valid json.
it would not neessiarly be a lot of work to correct this gap and just supprot a list of json obejct for the alias as well we just never got around to it.
there is no technial reason not to do that, its just that no one has wirttign the patch to do it.
this is a somewhat trivial feature to add and i think it woudl fit in the scope of a specless blueprint
i know it was intentionally not done when i twas doen for the pci_passthrough_whitelist but beyond limiting scope i dont recall the reason why both were not updated. so its not a bug but it is a painpoint for anyone who tryes to treat oslo.config files as ini files they are not and ini parser dont supprot multi-value filed
Michel
Le 06/06/2025 à 15:33, Thomas Goirand a écrit :
On 6/6/25 13:08, Michel Jouvin wrote:
Hi,
We need to support several GPU models in our Nova configuration. This normally requires to add multiple `alias` entries (lines) in the [pci] section of nova.conf. Unfortunately for us, it complicates a lot the generation of nova.conf by our system configuration management tool (where the section is represented by a dict/hash, meaning that there is only 1 possible entry for 'alias'). Before trying to hack our tool, we were wondering if there is a way to put the different values as a list for a single 'alias' line and what should be the separator or syntax ?
I was not able to identify a generic description of the syntax for multivalued parameters, if there is a generic rule. I already found this limitation (but we could live with it) for Keystone [federation]trusted_dashboard for example...
Thanks in advance for any hint. Best regards,
Michel
As much as I know, you *must* define multiple times the alias directive. For example, in your nova-scheduler / nova-api / nova-conductor nodes (I believe it should be in your scheduler nodes, not sure if api and conductor needs that...) you must have something like this:
alias={"vendor_id":"10de","product_id":"25b6","name":"nvidia-a2","device_type":"type-PF"}
alias={"vendor_id":"10de","product_id":"27b8","name":"nvidia-l4","device_type":"type-PF"}
to define aliases for Nvidia A2 and L4. This should match what you have it compute nodes, that may have the same alias directive.
I hope this helps, Cheers,
Thomas Goirand (zigo)
participants (4)
-
Arnaud Morin
-
Michel Jouvin
-
Sean Mooney
-
Thomas Goirand