hey, any discussion or feedback on this? 🙂

I missed this issue, sorry for that :(
I guess that it can make sense but I can me missing something.
@tomkerkhove @Eldarrin , WDYT about this option?

IT looks fine to me, there is an existing function that already strips the agent version from the demand array so that could be extended. Although I would suggest looking at the parent matching system rather than the demand matching system as although that is more complex to initially set up that passes the scaling problem back to ADO to handle the agent matching paradigms so that keda doesn't have to do it.

is the parent approach worth it for your use case @jan-mrm ?

@JorTurFer I have looked at it a while ago but I didn't really understand how to use it I guess. I can take another look at it

If you are struggling reach out and I can help. If the documentation is insufficient I probably need to improve it :)

I'm also facing this. Random azure pipeline tasks like CMake adds "invisible" demands to a job, release pipelines also has demands that's added based on what tasks are being used that can't be removed.

A workaround for this would be to not use the requireAllDemands and just generate unique permutation of all demands.
An example of this would be turning the following separate demands cpu-16, cpu-32, mem-8, mem-32, into cpu-16-mem-16, cpu-16-mem-32 etc..
That will avoid the issue where a demand matches multiple scale definitions, as mentioned in the docs:

Note: If more than one scaling definition is able to fulfill the demands of the job then they will both spin up an agent.

I don't think the suggestion of adding a demandsToIgnore would scale well, because a list like this would need to be constantly updated. Using a "parent" would also not solve my use-case, I think.

In my opinion, this could be solved in a few ways:

• Change the scaling behavior to only dispatch a single job even if multiple demands match.
• Add a demandApproveList that can include all the demands you want to consider when matching.

Example using approve list:

demands: mem-8,cpu-16
requireAllDemands: true
demandApproveList: cpu-16,cpu-32,mem-8,mem-32

So even if "CMake" is part of the demands, it will not be considered. The downside of this is that all definitions need to know about all the demands, but that could be easily automated using helm.

Edit: If possible, making the demandApproveList a "global" KEDA configuration would probably be better.

I don't think the suggestion of adding a demandsToIgnore would scale well, because a list like this would need to be constantly updated. Using a "parent" would also not solve my use-case, I think.

I see your point. If there are new demands, which are added by task, encountered, then the list would need to be updated. Not sure how often that happens and for my use case I'd think that's okay. Also since you would make sure that the self-hosted agent actually fulfils the demand. How many are known to you at this point, besides cmake?

• Add a demandApproveList that can include all the demands you want to consider when matching.

demands: mem-8,cpu-16
requireAllDemands: true
demandApproveList: cpu-16,cpu-32,mem-8,mem-32

I think I do not fully understand your demandApproveList idea and the example yet. Could you explain it again?
I see you set the two demands and requireAllDemands. What is the effect of the list in the trigger definition. For example what does the cpu-32 demand in the list do?
To be triggered a pipeline would have set the two required demands.

Just another idea:

Add a flag like allowAdditionalDemands as a boolean. Since requireAllDemands exactly matches the given demands and does not allow 'more' / 'additional' demands. (That it does not allow less demands is the expected behavior but an idea would be to allow any additional)

That would not need any lists to be updated or demands to be known.

What do you think about that?

Edit: Or a change of the requireAllDemands behavior to allow additional demands in general (without a new flag), but that would mean a behavior change of a current feature.

As I mentioned in my edit, the demandApproveList would make more sense as a "global" config and would tell KEDA what demands to consider when matching and ignore anything else, but I think KEDA is designed in a way that makes that hard, because each scale definition seems very "standalone".

The main issue now, is that demands: mem-8,cpu-16 without requireAllDemands would mach any subset of that list, as far as I understand? So a job with only mem-8 demand would match.
Adding a allowAdditionalDemands would make little sense as you would need the following config that would look a bit contradicting:

demands: mem-8,cpu-16
requireAllDemands: true
allowAdditionalDemands: true

What we need is a flag that conveys "require at least all specified demands, ignore anything else", but coming up with a user friendly name for it seems difficult.
Here's a few suggestions from chatgpt:

1. requireExactOrSupersetDemands
2. ignoreUnspecifiedDemands
3. exactOrSupersetDemandsOnly
4. strictDemandMatching
5. minimumRequiredDemands
6. matchAtLeastSpecifiedDemands
7. enforceSpecifiedDemands
8. mandatoryDemandsOnly
9. requireAndIgnoreOthers
10. demandSubsetRestriction

As I mentioned in my edit, the demandApproveList would make more sense as a "global" config and would tell KEDA what demands to consider when matching and ignore anything else, but I think KEDA is designed in a way that makes that hard, because each scale definition seems very "standalone".

Alright, kind of got it.

The main issue now, is that demands: mem-8,cpu-16 without requireAllDemands would mach any subset of that list, as far as I understand? So a job with only mem-8 demand would match. Adding a allowAdditionalDemands would make little sense as you would need the following config that would look a bit contradicting:

demands: mem-8,cpu-16
requireAllDemands: true
allowAdditionalDemands: true

Yes that is true. Having to set both flags seems ugly and also the allowAdditionalDemands would seem to have no effect when not also setting requireAllDemands.

What we need is a flag that conveys "require at least all specified demands, ignore anything else"

So just so sum up the idea:
We should not change the behavior of the current requireAllDemands? So if not then the idea is to add one additional flag besides requireAllDemands.
requireAllDemands would stay as it is right now, as the exact match.
The new flag - something like requireAllDemandsAndIgnoreOthers (just something to convey the meaning here, the actual user friendly name would need to be decided) - would check that all given demands from field demands are present but any additional ones defined in the pipeline would be ignored/accepted.

Is that right?

How should we handle setting both flags to true since they conflict?

How should we handle setting both flags to true since they conflict?

Because requireAllDemands is a "stronger" rule, I'm thinking it can take precedence.

I opened a draft PR just to get the ball rolling on this.

maybe @JorTurFer and/or @Eldarrin have feedback to this idea Nohac an I discussed (see draft PR of Nohac):
not having a list of demands to ignore anymore (original idea of this issue) but a less strict version of requireAllDemands which does allow additional demands

I think that the approach proposed by @Nohac of having different "matching" rules can bring a lot of flexibility. @tomkerkhove @Eldarrin ?

I feel like this is a relatively low risk feature to add, and shouldn't need to much consideration apart from the naming. If my changes looks OK and we can agree on the name, I will publish the PR I made and open a PR to update the docs as well.

Ping @tomkerkhove @Eldarrin ?

PR looks fine to me, its non breaking :)