devin-donnelly
GitHub
commit
a926c3959e
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@ -86,7 +86,6 @@ Before you start deploying applications as Pet Sets, there are a few limitations
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* As with all alpha/beta resources, it can be disabled through the `--runtime-config` option passed to the apiserver, and in fact most likely will be disabled on hosted offerings of Kubernetes.
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* The only updatable field on a PetSet is `replicas`
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* The storage for a given pet must either be provisioned by a [dynamic storage provisioner](http://releases.k8s.io/{{page.githubbranch}}/examples/experimental/persistent-volume-provisioning/README.md) based on the requested `storage class`, or pre-provisioned by an admin. Note that dynamic volume provisioning is also currently in alpha.
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* Deleting the Pet Set *will not* delete any pets. You will either have to manually scale it down to 0 pets first, or delete the pets yourself.
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* Deleting and/or scaling a PetSet down will *not* delete the volumes associated with the PetSet. This is done to ensure safety first, your data is more valuable than an auto purge of all related PetSet resources. **Deleting the Persistent Volume Claims will result in a deletion of the associated volumes**.
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* All PetSets currently require a "governing service", or a Service responsible for the network identity of the pets. The user is responsible for this Service.
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* Updating an existing PetSet is currently a manual process, meaning you either need to deploy a new PetSet with the new image version, or orphan Pets one by one, update their image, and join them back to the cluster.
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@ -122,7 +121,7 @@ web-1 1/1 Running 0 10m
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### Stable storage
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2 persistent volumes, one per pod. This is auto created by the Pet Set based on the `volumeTemplate` field
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2 persistent volumes, one per pod. This is auto created by the PetSet based on the `volumeClaimTemplate` field
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```shell
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$ kubectl get pv
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@ -243,7 +242,7 @@ nginx.default.svc.cluster.local service = 10 50 0 web-0.ub.default.svc.cluster.l
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## Updating a PetSet
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You cannot update any field of the PetSet except `spec.replicas`. You can update the replicas field using standard kubectl update commands like [patch](/docs/user-guide/kubectl/kubectl_patch) and [edit](/docs/user-guide/kubectl/kubectl_edit). Pet Set currently *does not* support image upgrade as noted in the section on [limitations](#alpha-limitations).
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You cannot update any field of the PetSet except `spec.replicas` and the `containers` in the podTemplate. Updating `spec.replicas` will scale the PetSet, updating `containers` will not have any effect till a Pet is deleted, at which time it is recreated with the modified podTemplate.
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## Scaling a PetSet
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@ -268,12 +267,97 @@ web-1 1/1 Running 0 46s
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web-2 1/1 Running 0 8s
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```
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## Deleting a Pet Set
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Cleaning up a Pet Set is somewhat manual, as noted in the [limitations section](#alpha-limitations). You can delete a Pet Set using Kubectl, but this will *not* scale it down to 0:
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You can also use the `kubectl scale` command:
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```shell
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$ kubectl delete -f petset.yaml
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$ kubectl get petset
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NAME DESIRED CURRENT AGE
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web 3 3 24m
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$ kubectl scale petset web --replicas=5
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petset "web" scaled
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$ kubectl get po --watch-only
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NAME READY STATUS RESTARTS AGE
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web-0 1/1 Running 0 10m
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web-1 1/1 Running 0 27m
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web-2 1/1 Running 0 10m
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web-3 1/1 Running 0 3m
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web-4 0/1 ContainerCreating 0 48s
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$ kubectl get petset web
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NAME DESIRED CURRENT AGE
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web 5 5 30m
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```
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Note however, that scaling up to N and back down to M *will not* delete the volumes of the M-N pets, as described in the section on [deletion](#deleting-a-petset), i.e scaling back up to M creates new pets that use the same volumes. To see this in action, scale the PetSet back down to 3:
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```shell
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$ kubectl get po --watch-only
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web-4 1/1 Terminating 0 4m
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web-4 1/1 Terminating 0 4m
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web-3 1/1 Terminating 0 6m
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web-3 1/1 Terminating 0 6m
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```
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Note that we still have 5 pvcs:
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```shell
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$ kubectl get pvc
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NAME STATUS VOLUME CAPACITY ACCESSMODES AGE
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www-web-0 Bound pvc-42ca5cef-8113-11e6-82f6-42010af00002 1Gi RWO 32m
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www-web-1 Bound pvc-42de30af-8113-11e6-82f6-42010af00002 1Gi RWO 32m
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www-web-2 Bound pvc-ba416413-8115-11e6-82f6-42010af00002 1Gi RWO 14m
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www-web-3 Bound pvc-ba45f19c-8115-11e6-82f6-42010af00002 1Gi RWO 14m
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www-web-4 Bound pvc-ba47674a-8115-11e6-82f6-42010af00002 1Gi RWO 14m
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```
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This allows you to upgrade the image of a petset and have it come back up with the same data, as described in the next section.
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## Image upgrades
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PetSet currently *does not* support automated image upgrade as noted in the section on [limitations](#alpha-limitations), however you can update the `image` field of any container in the podTemplate and delete Pets one by one, the PetSet controller will recreate it with the new image.
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Edit the image on the PetSet to `gcr.io/google_containers/nginx-slim:0.7` and delete 1 Pet:
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```shell{% raw %}
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$ for p in 0 1 2; do kubectl get po web-$p --template '{{range $i, $c := .spec.containers}}{{$c.image}}{{end}}'; echo; done
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gcr.io/google_containers/nginx-slim:0.8
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gcr.io/google_containers/nginx-slim:0.8
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gcr.io/google_containers/nginx-slim:0.8
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$ kubectl delete po web-0
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pod "web-0" deleted
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$ for p in 0 1 2; do kubectl get po web-$p --template '{{range $i, $c := .spec.containers}}{{$c.image}}{{end}}'; echo; done
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gcr.io/google_containers/nginx-slim:0.7
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gcr.io/google_containers/nginx-slim:0.8
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gcr.io/google_containers/nginx-slim:0.8
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{% endraw %}```
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Delete the remaining 2:
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```shell
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$ kubectl delete po web-1 web-2
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pod "web-1" deleted
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pod "web-2" deleted
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```
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Wait till the PetSet is stable and check the images:
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```shell{% raw %}
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$ for p in 0 1 2; do kubectl get po web-$p --template '{{range $i, $c := .spec.containers}}{{$c.image}}{{end}}'; echo; done
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gcr.io/google_containers/nginx-slim:0.7
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gcr.io/google_containers/nginx-slim:0.7
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gcr.io/google_containers/nginx-slim:0.7
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{% endraw %}```
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## Deleting a PetSet
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Deleting a PetSet through kubectl will scale it down to 0, thereby deleting all the Pets. If you wish to delete just the PetSet and not the Pets, use `--cascade=false`:
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```shell
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$ kubectl delete -f petset.yaml --cascade=false
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petset "web" deleted
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$ kubectl get po -l app=nginx
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