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Updated due to a clusteradm update.[2/2] #381

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Updated due to a clusteradm update.[2/2] #381

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The distribute-workload-with-placement is being updated due to a clus…
ydFu Aug 28, 2023
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[zh] Update distribute-workload-with-placement.md
ydFu Aug 29, 2023
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264 changes: 132 additions & 132 deletions content/en/scenarios/distribute-workload-with-placement.md
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Original file line number Diff line number Diff line change
Expand Up @@ -20,8 +20,8 @@ OCM addon [application lifecycle management]({{< ref "/getting-started/integrati
will also use placement to deploy applications in the future.

Some popular open source projects also integrate with the `Placement` API. For
example [Argo](https://github.com/argoproj/argo-cd), it can leverage the
generated `PlacementDecision` to drive the assignment of Argo Applications to a
example [Argo CD](https://github.com/argoproj/argo-cd), it can leverage the
generated `PlacementDecision` to drive the assignment of Argo CD Applications to a
desired set of clusters, details see this [example](https://github.com/argoproj/applicationset/tree/master/examples/clusterDecisionResource).
And [KubeVela](https://github.com/kubevela/kubevela), as an implementation of
the open application model, also will take advantage of the `Placement` API for
Expand Down Expand Up @@ -57,168 +57,168 @@ managed clusters.
1) Following [setup dev environment by kind](https://github.com/open-cluster-management-io/OCM/tree/main/solutions/setup-dev-environment)
to prepare an environment.

```shell
curl -sSL https://raw.githubusercontent.com/open-cluster-management-io/OCM/main/solutions/setup-dev-environment/local-up.sh | bash
```
```shell
curl -sSL https://raw.githubusercontent.com/open-cluster-management-io/OCM/main/solutions/setup-dev-environment/local-up.sh | bash
```

2) Confirm there are 2 `ManagedCluster` and a default `ManagedClusterSet` created.

```shell
$ clusteradm get clusters
NAME ACCEPTED AVAILABLE CLUSTERSET CPU MEMORY KUBERENETES VERSION
cluster1 true True default 24 49265496Ki v1.23.4
cluster2 true True default 24 49265496Ki v1.23.4
```shell
$ clusteradm get clusters
NAME ACCEPTED AVAILABLE CLUSTERSET CPU MEMORY KUBERNETES VERSION
cluster1 true True default 24 49265496Ki v1.23.4
cluster2 true True default 24 49265496Ki v1.23.4

$ clusteradm get clustersets
NAME BOUND NAMESPACES STATUS
default 2 ManagedClusters selected
```
$ clusteradm get clustersets
NAME BOUND NAMESPACES STATUS
default 2 ManagedClusters selected
```

3) Bind the default `ManagedClusterSet` to default `Namespace`.

```shell
clusteradm clusterset bind default --namespace default
```

```shell
$ clusteradm get clustersets
NAME BOUND NAMESPACES STATUS
default default 2 ManagedClusters selected
```

Note: click [here](https://open-cluster-management.io/concepts/managedclusterset/#operates-managedclusterset-using-clusteradm)
to see more details about how to operate `ManagedClusterSet` using `clusteradm`.

4) Create a `Placement` placement1 to select the 2 clusters in default `ManagedClusterSet`.

```shell
cat << EOF | kubectl apply -f -
apiVersion: cluster.open-cluster-management.io/v1beta1
kind: Placement
metadata:
name: placement1
namespace: default
spec:
numberOfClusters: 2
clusterSets:
- default
EOF
```
```shell
clusteradm clusterset bind default --namespace default
```

```shell
$ clusteradm get clustersets
NAME BOUND NAMESPACES STATUS
default default 2 ManagedClusters selected
```

Note: click [here](https://open-cluster-management.io/concepts/managedclusterset/#operates-managedclusterset-using-clusteradm)
to see more details about how to operate `ManagedClusterSet` using `clusteradm`.

4) Create a `Placement` placement1 to select the two clusters in default `ManagedClusterSet`.

```shell
cat << EOF | kubectl apply -f -
apiVersion: cluster.open-cluster-management.io/v1beta1
kind: Placement
metadata:
name: placement1
namespace: default
spec:
numberOfClusters: 2
clusterSets:
- default
EOF
```

5) Use `clusteradm` command to create `ManifestWork` my-first-work with
`Placement` placement1.

```shell
clusteradm create work my-first-work -f work.yaml --placement default/placement1
```
```shell
clusteradm create work my-first-work -f work.yaml --placement default/placement1
```

The `work.yaml` contains kubernetes resource definitions, for sample:
The `work.yaml` contains kubernetes resource definitions, for sample:

```shell
$ cat work.yaml
apiVersion: v1
kind: ServiceAccount
metadata:
namespace: default
name: my-sa
---
apiVersion: apps/v1
kind: Deployment
metadata:
namespace: default
name: nginx-deployment
labels:
app: nginx
spec:
replicas: 3
selector:
matchLabels:
app: nginx
template:
```shell
$ cat work.yaml
apiVersion: v1
kind: ServiceAccount
metadata:
namespace: default
name: my-sa
---
apiVersion: apps/v1
kind: Deployment
metadata:
namespace: default
name: nginx-deployment
labels:
app: nginx
spec:
serviceAccountName: my-sa
containers:
- name: nginx
image: nginx:1.14.2
ports:
- containerPort: 80
```
replicas: 3
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
serviceAccountName: my-sa
containers:
- name: nginx
image: nginx:1.14.2
ports:
- containerPort: 80
```

6) Check the `ManifestWork`, it should be distributed to both cluster1 and cluster2.

```shell
$ kubectl get manifestwork -A
NAMESPACE NAME AGE
cluster1 my-first-work 28s
cluster2 my-first-work 28s
```
```shell
$ kubectl get manifestwork -A
NAMESPACE NAME AGE
cluster1 my-first-work 28s
cluster2 my-first-work 28s
```

7) Update the `Placement` placement1 to select only 1 managed cluster.
7) Update the `Placement` placement1 to select only one managed cluster.

```shell
kubectl patch placement placement1 --patch '{"spec": {"clusterSets": ["default"],"numberOfClusters": 1}}' --type=merge
```
```shell
kubectl patch placement placement1 --patch '{"spec": {"clusterSets": ["default"],"numberOfClusters": 1}}' --type=merge
```

8) As the placement decision changes, running below command to reschedule
`ManifestWork` my-first-work to the newly selected cluster.

```shell
clusteradm create work my-first-work -f work.yaml --placement default/placement1 --overwrite
```
```shell
clusteradm create work my-first-work -f work.yaml --placement default/placement1 --overwrite
```

9) Check the `ManifestWork` again, now it's only deployed to cluster1.

```shell
$ kubectl get manifestwork -A
NAMESPACE NAME AGE
cluster1 my-first-work 18m
```
```shell
$ kubectl get manifestwork -A
NAMESPACE NAME AGE
cluster1 my-first-work 18m
```

## What happens behind the scene

The main idea is that `clusteradm` parse the selected clusters generated by
`Placement`, and fill in that as `ManifestWork` namespace. Then create the
`ManifestWork` and it would be distributed to a set of clusters. Let's see more
details.
`ManifestWork` and it would be distributed to a set of clusters.
Let's see more details.

1) `Placement` placement1 generates a `PlacementDecision` placement1-decision-1.

```shell
✗ kubectl get placementdecision -n default -l cluster.open-cluster-management.io/placement=placement1 -oyaml
apiVersion: v1
items:
- apiVersion: cluster.open-cluster-management.io/v1beta1
kind: PlacementDecision
metadata:
creationTimestamp: "2022-07-06T15:03:12Z"
generation: 1
labels:
cluster.open-cluster-management.io/placement: placement1
name: placement1-decision-1
namespace: default
ownerReferences:
```shell
$ kubectl get placementdecision -n default -l cluster.open-cluster-management.io/placement=placement1 -oyaml
apiVersion: v1
items:
- apiVersion: cluster.open-cluster-management.io/v1beta1
blockOwnerDeletion: true
controller: true
kind: Placement
name: placement1
uid: aa339f57-0eb7-4260-8d4d-f30c1379fd35
resourceVersion: "47679"
uid: 9f948619-1647-429d-894d-81e11dd8bcf1
status:
decisions:
- clusterName: cluster1
reason: ""
- clusterName: cluster2
reason: ""
kind: List
metadata:
resourceVersion: ""
selfLink: ""
```
kind: PlacementDecision
metadata:
creationTimestamp: "2022-07-06T15:03:12Z"
generation: 1
labels:
cluster.open-cluster-management.io/placement: placement1
name: placement1-decision-1
namespace: default
ownerReferences:
- apiVersion: cluster.open-cluster-management.io/v1beta1
blockOwnerDeletion: true
controller: true
kind: Placement
name: placement1
uid: aa339f57-0eb7-4260-8d4d-f30c1379fd35
resourceVersion: "47679"
uid: 9f948619-1647-429d-894d-81e11dd8bcf1
status:
decisions:
- clusterName: cluster1
reason: ""
- clusterName: cluster2
reason: ""
kind: List
metadata:
resourceVersion: ""
selfLink: ""
```

2) `clusteradm` get the `PlacementDecision` generated by `Placment`
placement1 with label `cluster.open-cluster-management.io/placement: placement1`,
Expand All @@ -228,9 +228,9 @@ namespace, reference [code](https://github.com/open-cluster-management-io/cluste
Then installs `ManifestWork` to namespace cluster1 and cluster2,
which will finally be distributed to the two clusters.

```shell
$ kubectl get manifestwork -A
NAMESPACE NAME AGE
cluster1 my-first-work 28s
cluster2 my-first-work 28s
```
```shell
$ kubectl get manifestwork -A
NAMESPACE NAME AGE
cluster1 my-first-work 28s
cluster2 my-first-work 28s
```
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