The Encyclopedia of Kubernetes clusters

Clusterpedia

This name Clusterpedia is inspired by Wikipedia. It is an encyclopedia of multi-cluster to synchronize, search for, and simply control multi-cluster resources.

Clusterpedia can synchronize resources with multiple clusters and provide more powerful search features on the basis of compatibility with Kubernetes OpenAPI to help you effectively get any multi-cluster resource that you are looking for in a quick and easy way.

The capability of Clusterpedia is not only to search for and view but also simply control resources in the future, just like Wikipedia that supports for editing entries.

Clusterpedia is a Cloud Native Computing Foundation sandbox project.

If you want to join the clusterpedia channel on CNCF slack, please get invite to CNCF slack and then join the #clusterpedia channel.

Why Clusterpedia

Clusterpedia can be deployed as a standalone platform or integrated with Cluster API, Karmada, Clusternet and other multi-cloud platforms

Automatic synchronization of clusters managed by multi-cloud platforms

The clusterpedia can automatically synchronize the resources within the cluster managed by the multi-cloud platform.

Users do not need to maintain Clusterpedia manually, Clusterpedia can work as well as the internal components of the multi-cloud platforms.

Lean More About Interfacing to Multi-Cloud Platforms

More retrieval features and compatibility with Kubernetes OpenAPI

• Support for retrieving resources using kubectl, client-go or controller-runtime/client, client-go example
• The resource metadata can be retrived via API or client-go/metadata
• Rich retrieval conditions: Filter by cluster/namespace/name/creation, Search by parent or ancestor owner,Multi-Cluster Label Selector, Enhanced Field Selector, Custom Search Conditions, etc.

Support for importing Kubernetes 1.10+

Automic conversion of different versions of Kube resources and support for multiple version of resources

• Even if you import different version of Kube, we can still use the same resource version to retrieve resources

For example, we can use v1, v1beta2, v1beta1 version to retrieve the Deployments resources in different clusters.

Notes: The version of deployments is v1beta1 in Kubernetes 1.10 and it is v1 in Kubernetes 1.24.

$ kubectl get --raw "/apis/clusterpedia.io/v1beta1/resources/apis/apps" | jq
{
  "kind": "APIGroup",
  "apiVersion": "v1",
  "name": "apps",
  "versions": [
    {
      "groupVersion": "apps/v1",
      "version": "v1"
    },
    {
      "groupVersion": "apps/v1beta2",
      "version": "v1beta2"
    },
    {
      "groupVersion": "apps/v1beta1",
      "version": "v1beta1"
    }
  ],
  "preferredVersion": {
    "groupVersion": "apps/v1",
    "version": "v1"
  }
}

A single API can be used to retrieve different types of resources

• Use Collection Resource to retrieve different types of resources, such as Deployment, DaemonSet, StatefulSet.

$ kubectl get collectionresources
NAME            RESOURCES
any             *
workloads       deployments.apps,daemonsets.apps,statefulsets.apps
kuberesources   .*,*.admission.k8s.io,*.admissionregistration.k8s.io,*.apiextensions.k8s.io,*.apps,*.authentication.k8s.io,*.authorization.k8s.io,*.autoscaling,*.batch,*.certificates.k8s.io,*.coordination.k8s.io,*.discovery.k8s.io,*.events.k8s.io,*.extensions,*.flowcontrol.apiserver.k8s.io,*.imagepolicy.k8s.io,*.internal.apiserver.k8s.io,*.networking.k8s.io,*.node.k8s.io,*.policy,*.rbac.authorization.k8s.io,*.scheduling.k8s.io,*.storage.k8s.io

Diverse policies and intelligent synchronization

• Wildcards can be used to sync all types of resources within a specified group or cluster.
• Support for synchronizing all custom resources
• The type and version of resources that Clusterpedia is synchroizing with can be adapted to you CRD and AA changes

Unify the search entry for master clusters and multi-cluster resources

• Based on Aggregated API, the entry portal for multi-cluster retrieval is the same as that of the master cluster(IP:PORT)

Very low memory usage and weak network optimization

• Optimized caches used by informer, so the memory usage is very low for resource synchronization.
• Automatic start/stop synchronization based on cluster health status

High availability

No dependency on specific storage components

Clusterpedia does not care about storage components and uses the storage layer to attach specific storage components, and will also add storage layers for graph databases and ES in the future

Architecture

The architecture consists of four parts:

• Clusterpedia APIServer: Register to Kubernetes APIServer by the means of Aggregated API and provide services through a unified entrance
• ClusterSynchro Manager: Manage the cluster synchro that is used to synchronize cluster resources
• Storage Layer: Connect with a specific storage component and then register to Clusterpedia APIServer and ClusterSynchro Manager via a storage layer interface
• Storage Component: A specific storage facility such as MySQL, PostgreSQL, Redis or other Graph Databases

In addition, Clusterpedia will use the Custom Resource - PediaCluster to implement cluster authentication and configure resources for synchronization.

Clusterpedia also provides a Default Storage Layer that can connect with MySQL and PostgreSQL.

Clusterpedia does not care about the specific storage components used by users, you can choose or implement the storage layer according to your own needs, and then register the storage layer in Clusterpedia as a plug-in

---

Installation | Import Clusters | Sync Cluster Resources

Search Label and URL Query

Role	Search label key	URL query
Filter cluster names	search.clusterpedia.io/clusters	clusters
Filter namespaces	search.clusterpedia.io/namespaces	namespaces
Filter resource names	search.clusterpedia.io/names	names
Fuzzy Search by resource name	internalstorage.clusterpedia.io/fuzzy-name	-
Since creation time	search.clusterpedia.io/since	since
Before creation time	search.clusterpedia.io/before	before
Specified Owner UID	search.clusterpedia.io/owner-uid	ownerUID
Specified Owner Seniority	search.clusterpedia.io/owner-seniority	ownerSeniority
Specified Owner Name	search.clusterpedia.io/owner-name	ownerName
Specified Owner Group Resource	search.clusterpedia.io/owner-gr	ownerGR
Order by fields	search.clusterpedia.io/orderby	orderby
Set page size	search.clusterpedia.io/size	limit
Set page offset	search.clusterpedia.io/offset	continue
Response include Continue	search.clusterpedia.io/with-continue	withContinue
Response include remaining count	search.clusterpedia.io/with-remaining-count	withRemainingCount
Custom Where SQL	-	whereSQL
Get only the metadata of the collection resource	-	onlyMetadata
Specify the groups of any collectionresource	-	groups
Specify the resources of any collectionresource	-	resources

Both Search Labels and URL Query support same operators as Label Selector:

• exist, not exist
• =, ==, !=
• in, notin

More information about Search Conditions, Label Selector and Field Selector

Usage Samples

You can search for resources configured in PediaCluster, Clusterpedia supports two types of resource search:

• Resources that are compatible with Kubernetes OpenAPI
• Collection Resource

$ kubectl api-resources | grep clusterpedia.io
collectionresources     clusterpedia.io/v1beta1  false   CollectionResource
resources               clusterpedia.io/v1beta1  false   Resources

Use a compatible way with Kubernetes OpenAPI

It is possible to search resources via URL, but using kubectl may be more convenient if you configured the cluster shortcuts for kubectl.

We can use kubectl --cluster <cluster name> to specify the cluster, if <cluster name> is clusterpedia, it meas it is a multi-cluster search operation.

First check which resources are synchronized. We cannot find a resource until it is properly synchronized:

$ kubectl --cluster clusterpedia api-resources
NAME                  SHORTNAMES   APIVERSION                     NAMESPACED   KIND
configmaps            cm           v1                             true         ConfigMap
events                ev           v1                             true         Event
namespaces            ns           v1                             false        Namespace
nodes                 no           v1                             false        Node
pods                  po           v1                             true         Pod
services              svc          v1                             true         Service
daemonsets            ds           apps/v1                        true         DaemonSet
deployments           deploy       apps/v1                        true         Deployment
replicasets           rs           apps/v1                        true         ReplicaSet
statefulsets          sts          apps/v1                        true         StatefulSet
cronjobs              cj           batch/v1                       true         CronJob
jobs                               batch/v1                       true         Job
clusters                           cluster.kpanda.io/v1alpha1     false        Cluster
ingressclasses                     networking.k8s.io/v1           false        IngressClass
ingresses             ing          networking.k8s.io/v1           true         Ingress
clusterrolebindings                rbac.authorization.k8s.io/v1   false        ClusterRoleBinding
clusterroles                       rbac.authorization.k8s.io/v1   false        ClusterRole
roles                              rbac.authorization.k8s.io/v1   true         Role

$ kubectl --cluster cluster-1 api-resources
...

Search in Multiple Clusters

Usage of multi-cluster search in documents

Get deployments in the kube-system namespace of all clusters:

$ kubectl --cluster clusterpedia get deployments -n kube-system
CLUSTER     NAME                      READY   UP-TO-DATE   AVAILABLE   AGE
cluster-1   coredns                   2/2     2            2           68d
cluster-2   calico-kube-controllers   1/1     1            1           64d
cluster-2   coredns                   2/2     2            2           64d

Get deployments in the two namespaces kube-system and default of all clusters:

$ kubectl --cluster clusterpedia get deployments -A -l "search.clusterpedia.io/namespaces in (kube-system, default)"
NAMESPACE     CLUSTER     NAME                      READY   UP-TO-DATE   AVAILABLE   AGE
kube-system   cluster-1   coredns                   2/2     2            2           68d
kube-system   cluster-2   calico-kube-controllers   1/1     1            1           64d
kube-system   cluster-2   coredns                   2/2     2            2           64d
default       cluster-2   dd-airflow-scheduler      0/1     1            0           54d
default       cluster-2   dd-airflow-web            0/1     1            0           54d
default       cluster-2   hello-world-server        1/1     1            1           27d
default       cluster-2   openldap                  1/1     1            1           41d
default       cluster-2   phpldapadmin              1/1     1            1           41d

Get deployments in the kube-system and default namespaces in cluster-1 and cluster-2:

$ kubectl --cluster clusterpedia get deployments -A -l "search.clusterpedia.io/clusters in (cluster-1, cluster-2),\
     search.clusterpedia.io/namespaces in (kube-system,default)"
NAMESPACE     CLUSTER     NAME                      READY   UP-TO-DATE   AVAILABLE   AGE
kube-system   cluster-1   coredns                   2/2     2            2           68d
kube-system   cluster-2   calico-kube-controllers   1/1     1            1           64d
kube-system   cluster-2   coredns                   2/2     2            2           64d
default       cluster-2   dd-airflow-scheduler      0/1     1            0           54d
default       cluster-2   dd-airflow-web            0/1     1            0           54d
default       cluster-2   hello-world-server        1/1     1            1           27d
default       cluster-2   openldap                  1/1     1            1           41d
default       cluster-2   phpldapadmin              1/1     1            1           41d

Get deployments in the kube-system and default namespaces in cluster-1 and cluster-2:

$ kubectl --cluster clusterpedia get deployments -A -l "search.clusterpedia.io/clusters in (cluster-1, cluster-2),\
    search.clusterpedia.io/namespaces in (kube-system,default),\
    search.clusterpedia.io/orderby=name"
NAMESPACE     CLUSTER     NAME                      READY   UP-TO-DATE   AVAILABLE   AGE
kube-system   cluster-2   calico-kube-controllers   1/1     1            1           64d
kube-system   cluster-1   coredns                   2/2     2            2           68d
kube-system   cluster-2   coredns                   2/2     2            2           64d
default       cluster-2   dd-airflow-scheduler      0/1     1            0           54d
default       cluster-2   dd-airflow-web            0/1     1            0           54d
default       cluster-2   hello-world-server        1/1     1            1           27d
default       cluster-2   openldap                  1/1     1            1           41d
default       cluster-2   phpldapadmin              1/1     1            1           41d

Search a specific cluster

Usage of specified cluster search in documents

If you want to search a specific cluster for any resource therein, you can add --cluster to specify the cluster name:

$ kubectl --cluster cluster-1 get deployments -A
NAMESPACE                           CLUSTER     NAME                                            READY   UP-TO-DATE   AVAILABLE   AGE
calico-apiserver                    cluster-1   calico-apiserver                                1/1     1            1           68d
calico-system                       cluster-1   calico-kube-controllers                         1/1     1            1           68d
calico-system                       cluster-1   calico-typha                                    1/1     1            1           68d
capi-system                         cluster-1   capi-controller-manager                         1/1     1            1           42d
capi-kubeadm-bootstrap-system       cluster-1   capi-kubeadm-bootstrap-controller-manager       1/1     1            1           42d
capi-kubeadm-control-plane-system   cluster-1   capi-kubeadm-control-plane-controller-manager   1/1     1            1           42d
capv-system                         cluster-1   capv-controller-manager                         1/1     1            1           42d
cert-manager                        cluster-1   cert-manager                                    1/1     1            1           42d
cert-manager                        cluster-1   cert-manager-cainjector                         1/1     1            1           42d
cert-manager                        cluster-1   cert-manager-webhook                            1/1     1            1           42d
clusterpedia-system                 cluster-1   clusterpedia-apiserver                          1/1     1            1           27m
clusterpedia-system                 cluster-1   clusterpedia-clustersynchro-manager             1/1     1            1           27m
clusterpedia-system                 cluster-1   clusterpedia-internalstorage-mysql              1/1     1            1           29m
kube-system                         cluster-1   coredns                                         2/2     2            2           68d
tigera-operator                     cluster-1   tigera-operator                                 1/1     1            1           68d

Except for search.clusterpedia.io/clusters, the support for other complex queries is same as that for multi-cluster search.

If you want to learn about the details of a resource, you need to specify which cluster it is:

$ kubectl --cluster cluster-1 -n kube-system get deployments coredns -o wide
CLUSTER     NAME      READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES                                                   SELECTOR
cluster-1   coredns   2/2     2            2           68d   coredns      registry.aliyuncs.com/google_containers/coredns:v1.8.4   k8s-app=kube-dns

Find the related pods by the name of the deployment

First view the deployments in default namespace

$ kubectl --cluster cluster-1 get deployments
NAME                      READY   UP-TO-DATE   AVAILABLE   AGE
fake-pod                  3/3     3            3           104d
test-controller-manager   0/0     0            0           7d21h

Use owner-name to specify Owner Name and use owner-seniority to promote the Owner's seniority.

$ kubectl --cluster cluster-1 get pods -l "search.clusterpedia.io/owner-name=fake-pod,search.clusterpedia.io/owner-seniority=1" 
NAME                                                 READY   STATUS      RESTARTS         AGE
fake-pod-698dfbbd5b-74cjx                            1/1     Running     0                12d
fake-pod-698dfbbd5b-tmcw7                            1/1     Running     0                3s
fake-pod-698dfbbd5b-wvtvw                            1/1     Running     0                3s

Lean More About Search by Parent or Ancestor Owner

Search for Collection Resource

Clusterpedia can also perform more advanced aggregation of resources. For example, you can use Collection Resource to get a set of different resources at once.

Let's first check which Collection Resource currently Clusterpedia supports:

$ kubectl get collectionresources
NAME        RESOURCES
any             *
workloads       deployments.apps,daemonsets.apps,statefulsets.apps
kuberesources   .*,*.admission.k8s.io,*.admissionregistration.k8s.io,*.apiextensions.k8s.io,*.apps,*.authentication.k8s.io,*.authorization.k8s.io,*.autoscaling,*.batch,*.certificates.k8s.io,*.coordination.k8s.io,*.discovery.k8s.io,*.events.k8s.io,*.extensions,*.flowcontrol.apiserver.k8s.io,*.imagepolicy.k8s.io,*.internal.apiserver.k8s.io,*.networking.k8s.io,*.node.k8s.io,*.policy,*.rbac.authorization.k8s.io,*.scheduling.k8s.io,*.storage.k8s.io

By getting workloads, you can get a set of resources aggregated by deployments, daemonsets, and statefulsets, and Collection Resource also supports for all complex queries.

kubectl get collectionresources workloads will get the corresponding resources of all namespaces in all clusters by default:

$ kubectl get collectionresources workloads
CLUSTER     GROUP   VERSION   KIND         NAMESPACE                     NAME                                          AGE
cluster-1   apps    v1        DaemonSet    kube-system                   vsphere-cloud-controller-manager              63d
cluster-2   apps    v1        Deployment   kube-system                   calico-kube-controllers                       109d
cluster-2   apps    v1        Deployment   kube-system                   coredns-coredns                               109d

Add the collection of Daemonset in cluster-1 and some of the above output is cut out

Due to the limitation of kubectl, you cannot use complex queries in kubectl and can only be queried by URL Query.

Lean More

Proposals

Perform more complex control over resources

In addition to resource search, similar to Wikipedia, Clusterpedia should also have simple capability of resource control, such as watch, create, delete, update, and more.

In fact, a write action is implemented by double write + warning response.

We will discuss this feature and decide whether we should implement it according to the community needs

Notes

Multi-cluster network connectivity

Clusterpedia does not actually solve the problem of network connectivity in a multi-cluster environment. You can use tools such as tower to connect and access sub-clusters, or use submariner or skupper to solve cross-cluster network problems.

Contact

If you have any question, feel free to reach out to us in the following ways:

• @cncf/clusterpedia slack

If you want to join the clusterpedia channel on CNCF slack, please get invite to CNCF slack and then join the #clusterpedia channel.

Contributors

Made with contrib.rocks.

License

Copyright 2023 the Clusterpedia Authors. All rights reserved.

Licensed under the Apache License, Version 2.0.