K
Q

create multiple persistent volumes in one .yaml

4/11/2019

I would like to dynamically provision 3 persistent volumes for my system, which are all based on a storageClass that I previously created. My v1 code does its job successfully.

v1:

apiVersion: v1
kind: PersistentVolume
metadata:
  name: volume0
  labels:
    type: storage-one
spec:
  storageClassName: storage-one
  accessModes:
    - ReadWriteMany
  capacity:
    storage: 2Gi
  hostPath:
    path: /somepath
    type: "DirectoryOrCreate"

---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: volume1
  labels:
    type: storage-one
spec:
  storageClassName: storage-one
  accessModes:
    - ReadWriteMany
  capacity:
    storage: 2Gi
  hostPath:
    path: /somepath
    type: "DirectoryOrCreate"

---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: volume2
  labels:
    type: storage-one
spec:
  storageClassName: storage-one
  accessModes:
    - ReadWriteMany
  capacity:
    storage: 2Gi
  hostPath:
    path: /somepath
    type: "DirectoryOrCreate"

I would like to refactor this code, possibly with a template that k8s can recognize, as the only variable here is the metadata.name. Is it possible?

-- user2309838
kubernetes

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1 Answer

4/11/2019

Natively kubernetes does not recognize any templates. But you can use any templating engine before you pass this yaml to kubectl.

Common practice is to use helm which uses gotpl inside. https://helm.sh/docs/chart_template_guide/

Your example will look like:

{{ range .Values.volume_names }}
---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: {{ . }}
  labels:
    type: storage-one
spec:
  storageClassName: storage-one
  accessModes:
    - ReadWriteMany
  capacity:
    storage: 2Gi
  hostPath:
    path: /somepath
    type: "DirectoryOrCreate"
{{ end }}

And values.yaml:

volume_names: 
- volume_this
- volume_that

Generally you can do render_with_your_fav_engine_to_stdout | kubectl apply -f using any engine.

UPD: Generate based on given len (this one was weird):

{{ range $k, $v := until (atoi .Values.numVolumes) }}
---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: volume-{{ $v }}
  labels:
    type: storage-one
spec:
  storageClassName: storage-one
  accessModes:
    - ReadWriteMany
  capacity:
    storage: 2Gi
  hostPath:
    path: /somepath
    type: "DirectoryOrCreate"
{{ end }}

And values.yaml:

numVolumes: "3"
-- Max Lobur
Source: StackOverflow