Open Cluster Management
ManifestWork
ManifestWork is to define a group of Kubernetes resource on the hub to be applied to the managed cluster. In the open-cluster-management project, a ManifestWork resource must be created in the cluster namespace. A work agent implemented in work project is run on the managed cluster and monitors the ManifestWork resource in the cluster namespace on the hub cluster.
An example of ManifestWork to deploy a deployment to the managed cluster is shown in the following example.
apiVersion: work.open-cluster-management.io/v1
kind: ManifestWork
metadata:
name: hello-work
namespace: cluster1
labels:
app: hello
spec:
workload:
manifests:
- apiVersion: apps/v1
kind: Deployment
metadata:
name: hello
namespace: default
spec:
selector:
matchLabels:
app: hello
template:
metadata:
labels:
app: hello
spec:
containers:
- name: hello
image: quay.io/asmacdo/busybox
command:
["sh", "-c", 'echo "Hello, Kubernetes!" && sleep 3600']
Work agent will track all the resources defined in ManifestWork and update the its status. There are two types of status in manifestwork. The resourceStatus tracks the status of each manifest in the ManifestWork and conditions reflects the overall status of the ManifestWork. Work agent currently checks whether a resource is Available, meaning the resource exists on the managed cluster, and Applied means the resource defined in ManifestWork has been applied to the managed cluster.
Here is an example.
apiVersion: work.open-cluster-management.io/v1
kind: ManifestWork
metadata:
labels:
app: hello
name: hello-work
namespace: cluster1
spec: ... ...
status:
conditions:
- lastTransitionTime: "2021-06-15T02:26:02Z"
message: Apply manifest work complete
reason: AppliedManifestWorkComplete
status: "True"
type: Applied
- lastTransitionTime: "2021-06-15T02:26:02Z"
message: All resources are available
reason: ResourcesAvailable
status: "True"
type: Available
resourceStatus:
manifests:
- conditions:
- lastTransitionTime: "2021-06-15T02:26:02Z"
message: Apply manifest complete
reason: AppliedManifestComplete
status: "True"
type: Applied
- lastTransitionTime: "2021-06-15T02:26:02Z"
message: Resource is available
reason: ResourceAvailable
status: "True"
type: Available
resourceMeta:
group: apps
kind: Deployment
name: hello
namespace: default
ordinal: 0
resource: deployments
version: v1
To ensure the resources applied by ManifestWork are reliably recorded, the work agent creates an AppliedManifestWork on the managed cluster for each ManifestWork as an anchor for resources relating to ManifestWork. When ManifestWork is deleted, work agent runs a Foreground deletion, that ManifestWork will stay in deleting state until all its related resources has been fully cleaned in the managed cluster.