> - Job: Job is a collection of different groups. Job is where the constraints for type of scheduler, update strategies and ACL is placed.
> - Group: Group is a collection of different tasks. A group is always executed on the same Nomad client node. You'll want to use Groups for use-cases like a logging sidecar, reverse proxies etc.
> - Task: Atomic unit of work. A task in Nomad can be running a container/binary/Java VM etc, defining the mount points, env variables, ports to be exposed etc.
> If you're coming from K8s you can think of Task as a Pod and Group as a Replicaset. There's no equivalent to Job in K8s.
Is that right? I haven't used Nomad (yet?) but, as described, it sounds to me more like Job ~= Deployment; Group ~= Pod; Task ~= Container?
A Task is an individual unit of work: a container, executable, JVM app, etc.
A Task Group/Allocation is a group of Tasks that will be placed together on nodes as a unit.
A Job is a collection of Task Groups and is where you tell Nomad how to schedule the work. A "system" Job is scheduled across all Nodes somewhat like a DaemonSet. A "batch" Job can be submitted as a one-off execution, periodic (run on a schedule) or parameterized (run on demand with variables specified at runtime). A "service" Job is the "normal" scheduler where all Task Groups are treated like ReplicaSets.
Placement is determined by constraints that can be specified on each Task Group.
Author here. Hm, now that you point this out, I do get your point. However you can't run multiple different Pods in a deployment (you can run multiple containers in a Pod), that's why a Job isn't really comparable to a ReplicaSet.
I could very well be wrong, but this is my understanding.
I think the tricky part is Nomad merges replica count + definition into Group, while K8s separates Pod/RS/Deployment (and uses RS to orchestrate upgrades, which I think Nomad handles on its own somehow?).
> - Group: Group is a collection of different tasks. A group is always executed on the same Nomad client node. You'll want to use Groups for use-cases like a logging sidecar, reverse proxies etc.
> - Task: Atomic unit of work. A task in Nomad can be running a container/binary/Java VM etc, defining the mount points, env variables, ports to be exposed etc.
> If you're coming from K8s you can think of Task as a Pod and Group as a Replicaset. There's no equivalent to Job in K8s.
Is that right? I haven't used Nomad (yet?) but, as described, it sounds to me more like Job ~= Deployment; Group ~= Pod; Task ~= Container?