Managing Clusters

updated: 2020-04-17 12:00

Managing Clusters¶

Clusters are first-class citizens in Senlin service design. A cluster is defined as a collection of homogeneous objects. The “homogeneous” here means that the objects managed (aka. Nodes) have to be instantiated from the same “profile type”.

List Clusters¶

To examine the list of receivers:

def list_cluster(conn):
    print("List clusters:")

    for cluster in conn.clustering.clusters():
        print(cluster.to_dict())

    for cluster in conn.clustering.clusters(sort='name:asc'):
        print(cluster.to_dict())

When listing clusters, you can specify the sorting option using the sort parameter and you can do pagination using the limit and marker parameters.

Full example: manage cluster

Create Cluster¶

When creating a cluster, you will provide a dictionary with keys and values according to the cluster type referenced.

def create_cluster(conn):
    print("Create cluster:")

    spec = {
        "name": CLUSTER_NAME,
        "profile_id": PROFILE_ID,
        "min_size": 0,
        "max_size": -1,
        "desired_capacity": 1,
    }

    cluster = conn.clustering.create_cluster(**spec)
    print(cluster.to_dict())

Optionally, you can specify a metadata keyword argument that contains some key-value pairs to be associated with the cluster.

Full example: manage cluster

Get Cluster¶

To get a cluster based on its name or ID:

def get_cluster(conn):
    print("Get cluster:")

    cluster = conn.clustering.get_cluster(CLUSTER_ID)
    print(cluster.to_dict())

Full example: manage cluster

Find Cluster¶

To find a cluster based on its name or ID:

def find_cluster(conn):
    print("Find cluster:")

    cluster = conn.clustering.find_cluster(CLUSTER_ID)
    print(cluster.to_dict())

Full example: manage cluster

Update Cluster¶

After a cluster is created, most of its properties are immutable. Still, you can update a cluster’s name and/or params.

def update_cluster(conn):
    print("Update cluster:")

    spec = {
        "name": "Test_Cluster001",
        "profile_id": "c0e3a680-e270-4eb8-9361-e5c9503fba0a",
        "profile_only": True,
    }
    cluster = conn.clustering.update_cluster(CLUSTER_ID, **spec)
    print(cluster.to_dict())

Full example: manage cluster

Delete Cluster¶

A cluster can be deleted after creation, When there are nodes in the cluster, the Senlin engine will launch a process to delete all nodes from the cluster and destroy them before deleting the cluster object itself.

def delete_cluster(conn):
    print("Delete cluster:")

    conn.clustering.delete_cluster(CLUSTER_ID)
    print("Cluster deleted.")

    # cluster support force delete
    conn.clustering.delete_cluster(CLUSTER_ID, False, True)
    print("Cluster deleted")

Cluster Add Nodes¶

Add some existing nodes into the specified cluster.

def cluster_add_nodes(conn):
    print("Add nodes to cluster:")

    node_ids = [NODE_ID]
    res = conn.clustering.cluster_add_nodes(CLUSTER_ID, node_ids)
    print(res)

Cluster Del Nodes¶

Remove nodes from specified cluster.

def cluster_del_nodes(conn):
    print("Remove nodes from a cluster:")

    node_ids = [NODE_ID]
    res = conn.clustering.cluster_del_nodes(CLUSTER_ID, node_ids)
    print(res)

Cluster Replace Nodes¶

Replace some existing nodes in the specified cluster.

def cluster_replace_nodes(conn):
    print("Replace the nodes in a cluster with specified nodes:")

    old_node = NODE_ID
    new_node = "cd803d4a-015d-4223-b15f-db29bad3146c"
    spec = {
        old_node: new_node
    }
    res = conn.clustering.cluster_replace_nodes(CLUSTER_ID, **spec)
    print(res)

Cluster Scale Out¶

Inflate the size of a cluster.

def cluster_scale_out(conn):
    print("Inflate the size of a cluster:")

    res = conn.clustering.cluster_scale_out(CLUSTER_ID, 1)
    print(res)

Cluster Scale In¶

Shrink the size of a cluster.

def cluster_scale_in(conn):
    print("Shrink the size of a cluster:")

    res = conn.clustering.cluster_scale_in(CLUSTER_ID, 1)
    print(res)

Cluster Resize¶

Resize of cluster.

def cluster_resize(conn):
    print("Resize of cluster:")

    spec = {
        'min_size': 1,
        'max_size': 6,
        'adjustment_type': 'EXACT_CAPACITY',
        'number': 2
    }
    res = conn.clustering.cluster_resize(CLUSTER_ID, **spec)
    print(res)

Cluster Policy Attach¶

Once a policy is attached (bound) to a cluster, it will be enforced when related actions are performed on that cluster, unless the policy is (temporarily) disabled on the cluster

def cluster_attach_policy(conn):
    print("Attach policy to a cluster:")

    spec = {'enabled': True}
    res = conn.clustering.cluster_attach_policy(CLUSTER_ID, POLICY_ID,
                                                **spec)
    print(res)

Cluster Policy Detach¶

Once a policy is attached to a cluster, it can be detached from the cluster at user’s request.

def cluster_detach_policy(conn):
    print("Detach a policy from a cluster:")

    res = conn.clustering.cluster_detach_policy(CLUSTER_ID, POLICY_ID)
    print(res)

Cluster Check¶

Check cluster health status, Cluster members can be check.

def check_cluster(conn):
    print("Check cluster:")

    res = conn.clustering.check_cluster(CLUSTER_ID)
    print(res)

Cluster Recover¶

To restore a specified cluster, members in the cluster will be checked.

def recover_cluster(conn):
    print("Recover cluster:")

    spec = {'check': True}
    res = conn.clustering.recover_cluster(CLUSTER_ID, **spec)
    print(res)

updated: 2020-04-17 12:00

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