Support for constraints in chronos

[mattomatic]

Is it possible to add support to chronos for constraints, such as those that marathon already supports (https://mesosphere.github.io/marathon/docs/constraints.html)?

For example, it would be very useful to be able to schedule jobs to be run in a particular data center.

Also, is there an existing workaround for this?

[brndnmtthws]

It's feasible, but not currently on any sort of roadmap. PRs welcome.

[elingg]

Adding constraints would be an important feature for Chronos. Patches from the community would be excellent if we aren't able to add this in our immediate roadmap.

[jwerak]

Having marathon-like constrains feature would be super cool - https://mesosphere.github.io/marathon/docs/constraints.html

[kutchar]

+1

[mjbroekman]

+1 ... having the ability to specify parts of your cluster to run jobs on would great...

[synergyhue]

+1

[ghost]

+1

[siddharth178]

+1

[freshmatrix]

+1

[SEJeff]

Hey gents, instead of a pointless +1, just click the Subscribe button on the top right. More and more +1s are not very useful and just spam the developers unnecessarily.

[ssk2]

@SEJeff, the +1s can be helpful for prioritisation. Ideally we'd have a less spammy system or the ability to vote built into GH issues, of course.

[SEJeff]

That is what subscribe is for :)

I comaintain a few largish open source projects (> 500 unique contributors each), salt and graphite. It works pretty well.

[gyllen]

@brndnmtthws How hard would this be to accomplish, do you have any idea. It is most certainly an important feature.

[kapil-malik]

This works pretty well now for us in latest version. Thanks. Curious why this issue is still open now?

[potto007]

Isn't it still restricted to just the EQUALS constraint at this point? I think the intent is to bring it to parity with Marathon wrt constraints.

[kapil-malik]

Oh yes, agreed.EQUALS was serving our purpose, didn't realize the full story. Thanks.

[goodwillcoding]

Is there a way to set constraints using the gui?

[ssk2]

@goodwillcoding - not yet but we're working on revamping the GUI!

[tony-kerz]

is there any support for running a job on every slave in a cluster?

[brndnmtthws]

Not yet. On Sep 4, 2015 1:27 PM, "tony kerz" notifications@github.com wrote:

is there any support for running a job on every slave in a cluster?

— Reply to this email directly or view it on GitHub https://github.com/mesos/chronos/issues/256#issuecomment-137711020.

[tony-kerz]

is something like below supposed to work?:

  "constraints": [
    ["hostname", "EQUALS", "ip-10-0-0-95.ec2.internal"]
  ],

[solarkennedy]

Yes. EQUALS is one of the supported constraints per the docs: https://mesos.github.io/chronos/docs/api.html#constraints

[tony-kerz]

thx @solarkennedy, i saw that, but it wasn't clear to me if hostname was an attribute that was auto-magically made available to chronos for use with EQUAL/LIKE constraints or if those would only work on attributes that i manually punched into a slave via something like --attributes (which i found somewhere in the mesos doc), or MESOS_ATTRIBUTES (which i see in the cloud-formation file provided by mesosphere).

looks like marathon is pretty good about setting up hostname for use with constraints, but i saw no such info in the chronos doc.

[solarkennedy]

That is true, the docs do assume that the attribute used by the constraint is declared. As far as I know hostname is not a magic attribute that you get for free.

Can you make a PR to clarify that and cross-link to the mesos docs on how to add attributes? If not I could do it.

[tony-kerz]

@solarkennedy i can take a whack at clarifying the docs.

more importantly tho, i think it would be great if hostname was made available by default for constraints as it is in marathon. do you think this would be a valuable feature? if so, do you think it is (or should be) implied by this particular issue, or do you think it should be spiked out as a sep enhancement request?

[solarkennedy]

I'm not sure. I was not aware that that was a "free" constraint that you could use from marathon, even if you didn't set that as a mesos attribute. (I assumed the constraint language only operated on mesos attributes)

[tony-kerz]

check the last sentence of the first paragraph at this link: https://mesosphere.github.io/marathon/docs/constraints.html

The field can be the slave hostname or any Mesos slave attribute.

i've constrained to hostname successfully in marathon as well without doing anything special.

[solarkennedy]

Ah! Today I learned. @tony-kerz for this specific feature I recommend making a separate issue/pr.

If you ask me this main issue should be closed, as there is some constraint functionality. Any new feature requests or doc updates and be new things.

[anhcuong]

Please support the hostname constraint in the future because I guess many people are using Marathon along with Chronos on top of Mesos. And Marathon already supported hostname constraint

[tony-kerz]

fyi @anhcuong i have had #563 open for a while to provide that feature.

[alex-hoang-piksel]

Is there any news on adding the constraints field to the UI? Currently when I set a constraint on a job, if the job is then edited and saved via the UI, the constraints field is emptied.

[anhcuong]

@alex-hoang-piksel you may want to check out Airflow (https://airflow.incubator.apache.org/). They provided many more features with a rich UI. And yeah, the repository is more active than Chronos.