Ceph » Orchestrator

in order to co-locate daemons, we have to use different ports for those new daemons.

service_type: rgw
service_id: realm.zone
placement:
  label: rgw
  count: 3
  allow-co-located: true

alternatively:

service_type: rgw
service_id: realm.zone
placement:
  hosts:
  - host1:1.2.3.0/24=name
  - host1:1.2.3.0/24=name
  - host2
  - host2

or

Edit: Doesn't work, as it breaks the possibility to name individual daemons

service_type: rgw
service_id: realm.zone
placement:
  hosts:
  - host1,count=8  # add "count" to host placement spec

or

Edit: IMO daemons-per-host is in conflict with count. And I don't see a clear use case except for rgw.py

service_type: rgw
service_id: realm.zone
placement:
  label: rgw
  count: 3
  daemons-per-host: 8 

or

Edit: IMO too complicated

placement:
  - label: rgw-big
    count-per-host: 8
    count: 24
  - label: rgw-small
    count: 2
  - hosts: host1
    names: a,b,c
    count-per-host: 3
  - label: foo
    count: 3

Kubernetes:

The below yaml snippet of the webserver deployment has podAntiAffinity and podAffinity configured. This informs the scheduler that all its replicas are to be co-located with pods that have selector label app=store. This will also ensure that each web-server replica does not co-locate on a single node.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: web-server
spec:
  selector:
    matchLabels:
      app: web-store
  replicas: 3
  template:
    metadata:
      labels:
        app: web-store
    spec:
      affinity:
        podAntiAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
          - labelSelector:
              matchExpressions:
              - key: app
                operator: In
                values:
                - web-store
            topologyKey: "kubernetes.io/hostname" 
        podAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
          - labelSelector:
              matchExpressions:
              - key: app
                operator: In
                values:
                - store
            topologyKey: "kubernetes.io/hostname" 
      containers:
      - name: web-app
        image: nginx:1.16-alpine