The project is currently alpha. While no breaking API changes are currently planned, we reserve the right to address bugs and change the API before the project is declared stable.
- Zookeeper Operator
- Project status: alpha
- Table of Contents
- Requirements
- Usage
- Development
This operator runs a Zookeeper 3.8.3 cluster, and uses Zookeeper dynamic reconfiguration to handle node membership.
The operator itself is built with the Operator framework.
- Access to a Kubernetes v1.15.0+ cluster
We recommend using our helm charts for all installation and upgrades. Since version 0.2.8 onwards, the helm charts for zookeeper operator and zookeeper cluster are published in https://charts.pravega.io. To add this repository to your Helm repos, use the following command
helm repo add pravega https://charts.pravega.io
However there are manual deployment and upgrade options available as well.
Note: if you are running on Google Kubernetes Engine (GKE), please check this first.
To understand how to deploy the zookeeper operator using helm, refer to this.
Register the ZookeeperCluster custom resource definition (CRD).
$ kubectl create -f config/crd/bases
You can choose to enable Zookeeper operator for all namespaces or just for a specific namespace. The example is using the default namespace, but feel free to edit the Yaml files and use a different namespace.
Create the operator role and role binding.
// default namespace
$ kubectl create -f config/rbac/default_ns_rbac.yaml
// all namespaces
$ kubectl create -f config/rbac/all_ns_rbac.yaml
Deploy the Zookeeper operator.
$ kubectl create -f config/manager/manager.yaml
Verify that the Zookeeper operator is running.
$ kubectl get deploy
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
zookeeper-operator 1 1 1 1 12m
To understand how to deploy a sample zookeeper cluster using helm, refer to this.
Create a Yaml file called zk.yaml with the following content to install a 3-node Zookeeper cluster.
apiVersion: "zookeeper.pravega.io/v1beta1"
kind: "ZookeeperCluster"
metadata:
name: "zookeeper"
spec:
replicas: 3$ kubectl create -f zk.yaml
After a couple of minutes, all cluster members should become ready.
$ kubectl get zk
NAME REPLICAS READY REPLICAS VERSION DESIRED VERSION INTERNAL ENDPOINT EXTERNAL ENDPOINT AGE
zookeeper 3 3 0.2.8 0.2.8 10.100.200.18:2181 N/A 94s
Note: when the Version field is set as well as Ready Replicas are equal to Replicas that signifies our cluster is in Ready state
Additionally, check the output of describe command which should show the following cluster condition
$ kubectl describe zk
Conditions:
Last Transition Time: 2020-05-18T10:17:03Z
Last Update Time: 2020-05-18T10:17:03Z
Status: True
Type: PodsReady
Note: User should wait for the Pods Ready condition to be True
$ kubectl get all -l app=zookeeper
NAME DESIRED CURRENT AGE
statefulsets/zookeeper 3 3 2m
NAME READY STATUS RESTARTS AGE
po/zookeeper-0 1/1 Running 0 2m
po/zookeeper-1 1/1 Running 0 1m
po/zookeeper-2 1/1 Running 0 1m
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
svc/zookeeper-client ClusterIP 10.31.243.173 <none> 2181/TCP 2m
svc/zookeeper-headless ClusterIP None <none> 2888/TCP,3888/TCP 2m
Note: If you want to configure zookeeper pod, for example to change the service account or the CPU limits, you can set the following properties: ~/charts/zookeeper/templates/zookeeper.yaml. Service account configuration is available from zookeeper operator version
0.2.9onwards.
apiVersion: "zookeeper.pravega.io/v1beta1"
kind: "ZookeeperCluster"
metadata:
name: "example"
spec:
pod:
serviceAccountName: "zookeeper"
resources:
requests:
cpu: 200m
memory: 256Mi
limits:
cpu: 200m
memory: 256Mi
Create a Yaml file called zk.yaml with the following content to install a 3-node Zookeeper cluster.
apiVersion: "zookeeper.pravega.io/v1beta1"
kind: "ZookeeperCluster"
metadata:
name: "example"
spec:
replicas: 3
storageType: ephemeral$ kubectl create -f zk.yaml
After a couple of minutes, all cluster members should become ready.
$ kubectl get zk
NAME REPLICAS READY REPLICAS VERSION DESIRED VERSION INTERNAL ENDPOINT EXTERNAL ENDPOINT AGE
example 3 3 0.2.7 0.2.7 10.100.200.18:2181 N/A 94s
Note: User should only provide value for either the field persistence or ephemeral in the spec if none of the values is specified default is persistence
Note: In case of ephemeral storage, the cluster may not be able to come back up if more than quorum number of nodes are restarted simultaneously.
Note: In case of ephemeral storage, there will be loss of data when the node gets restarted.
Create a Yaml file called zk-with-istio.yaml with the following content to install a 3-node Zookeeper cluster.
apiVersion: zookeeper.pravega.io/v1beta1
kind: ZookeeperCluster
metadata:
name: zk-with-istio
spec:
replicas: 3
config:
initLimit: 10
tickTime: 2000
syncLimit: 5
quorumListenOnAllIPs: true$ kubectl create -f zk-with-istio.yaml
To understand how to upgrade the zookeeper cluster using helm, refer to this.
To initiate an upgrade process manually, a user has to update the spec.image.tag field of the ZookeeperCluster custom resource. This can be done in three different ways using the kubectl command.
kubectl edit zk <name>, modify thetagvalue in the YAML resource, save, and exit.- If you have the custom resource defined in a local YAML file, e.g.
zk.yaml, you can modify thetagvalue, and reapply the resource withkubectl apply -f zk.yaml. kubectl patch zk <name> --type='json' -p='[{"op": "replace", "path": "/spec/image/tag", "value": "X.Y.Z"}]'.
After the tag field is updated, the StatefulSet will detect the version change and it will trigger the upgrade process.
To detect whether a ZookeeperCluster upgrade is in progress or not, check the output of the command kubectl describe zk. Output of this command should contain the following entries
$ kubectl describe zk
status:
Last Transition Time: 2020-05-18T10:25:12Z
Last Update Time: 2020-05-18T10:25:12Z
Message: 0
Reason: Updating Zookeeper
Status: True
Type: Upgrading
Additionally, the Desired Version will be set to the version that we are upgrading our cluster to.
$ kubectl get zk
NAME REPLICAS READY REPLICAS VERSION DESIRED VERSION INTERNAL ENDPOINT EXTERNAL ENDPOINT AGE
zookeeper 3 3 0.2.6 0.2.7 10.100.200.126:2181 N/A 11m
Once the upgrade completes, the Version field is set to the Desired Version, as shown below
$ kubectl get zk
NAME REPLICAS READY REPLICAS VERSION DESIRED VERSION INTERNAL ENDPOINT EXTERNAL ENDPOINT AGE
zookeeper 3 3 0.2.7 0.2.7 10.100.200.126:2181 N/A 11m
Additionally, the Upgrading status is set to False and PodsReady status is set to True, which signifies that the upgrade has completed, as shown below
$ kubectl describe zk
Status:
Conditions:
Last Transition Time: 2020-05-18T10:28:22Z
Last Update Time: 2020-05-18T10:28:22Z
Status: True
Type: PodsReady
Last Transition Time: 2020-05-18T10:28:22Z
Last Update Time: 2020-05-18T10:28:22Z
Status: False
Type: Upgrading
Note: The value of the tag field should not be modified while an upgrade is already in progress.
For upgrading the zookeeper operator check the document operator-upgrade
Refer to this.
$ kubectl delete -f zk.yaml
Note that the Zookeeper clusters managed by the Zookeeper operator will NOT be deleted even if the operator is uninstalled.
Refer to this.
To delete all clusters, delete all cluster CR objects before uninstalling the operator.
$ kubectl delete -f config/manager/manager.yaml
$ kubectl delete -f config/rbac/default_ns_rbac.yaml
// or, depending on how you deployed it
$ kubectl delete -f config/rbac/all_ns_rbac.yaml
The AdminServer is an embedded Jetty server that provides an HTTP interface to the four letter word commands. This port is made accessible to the outside world via the AdminServer service. By default, the server is started on port 8080, but this configuration can be modified by providing the desired port number within the values.yaml file of the zookeeper cluster charts
ports:
- containerPort: 8118
name: admin-server
This would bring up the AdminServer service on port 8118 as shown below
$ kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S)
zookeeper-admin-server LoadBalancer 10.100.200.104 10.243.39.62 8118:30477/TCP
The commands are issued by going to the URL /commands/<command name>, e.g. http://10.243.39.62:8118/commands/stat
The list of available commands are
/commands/configuration
/commands/connection_stat_reset
/commands/connections
/commands/dirs
/commands/dump
/commands/environment
/commands/get_trace_mask
/commands/hash
/commands/initial_configuration
/commands/is_read_only
/commands/last_snapshot
/commands/leader
/commands/monitor
/commands/observer_connection_stat_reset
/commands/observers
/commands/ruok
/commands/server_stats
/commands/set_trace_mask
/commands/stat_reset
/commands/stats
/commands/system_properties
/commands/voting_view
/commands/watch_summary
/commands/watches
/commands/watches_by_path
/commands/zabstate
Requirements:
- Go 1.21+
Use the make command to build the Zookeeper operator image.
$ make build
That will generate a Docker image with the format
<latest_release_tag>-<number_of_commits_after_the_release> (it will append-dirty if there are uncommitted changes). The image will also be tagged as latest.
Example image after running make build.
The Zookeeper operator image will be available in your Docker environment.
$ docker images pravega/zookeeper-operator
REPOSITORY TAG IMAGE ID CREATED SIZE
pravega/zookeeper-operator 0.1.1-3-dirty 2b2d5bcbedf5 10 minutes ago 41.7MB
pravega/zookeeper-operator latest 2b2d5bcbedf5 10 minutes ago 41.7MB
Optionally push it to a Docker registry.
docker tag pravega/zookeeper-operator [REGISTRY_HOST]:[REGISTRY_PORT]/pravega/zookeeper-operator
docker push [REGISTRY_HOST]:[REGISTRY_PORT]/pravega/zookeeper-operator
where:
[REGISTRY_HOST]is your registry host or IP (e.g.registry.example.com)[REGISTRY_PORT]is your registry port (e.g.5000)
For debugging and development you might want to access the Zookeeper cluster directly. For example, if you created the cluster with name zookeeper in the default namespace you can forward the Zookeeper port from any of the pods (e.g. zookeeper-0) as follows:
$ kubectl port-forward -n default zookeeper-0 2181:2181
You can run the operator locally to help with development, testing, and debugging tasks.
The following command will run the operator locally with the default Kubernetes config file present at $HOME/.kube/config. Use the --kubeconfig flag to provide a different path.
$ make run-local
The Operator requires elevated privileges in order to watch for the custom resources.
According to Google Container Engine docs:
Ensure the creation of RoleBinding as it grants all the permissions included in the role that we want to create. Because of the way Container Engine checks permissions when we create a Role or ClusterRole.
An example workaround is to create a RoleBinding that gives your Google identity a cluster-admin role before attempting to create additional Role or ClusterRole permissions.
This is a known issue in the Beta release of Role-Based Access Control in Kubernetes and Container Engine version 1.6.
On GKE, the following command must be run before installing the operator, replacing the user with your own details.
$ kubectl create clusterrolebinding your-user-cluster-admin-binding --clusterrole=cluster-admin [email protected]
To setup minikube locally you can follow the steps mentioned here.
Once minikube setup is complete, minikube start will create a minikube VM.
First install the zookeeper operator in either of the ways mentioned here. Since minikube provides a single node Kubernetes cluster which has a low resource provisioning, we provide a simple way to install a small zookeeper cluster on a minikube environment using the following command.
helm install zookeeper charts/zookeeper --values charts/zookeeper/values/minikube.yaml
Zookeeper Exporter is a binary which is used to generate YAML file for all the secondary resources which Zookeeper Operator deploys to the Kubernetes Cluster. It takes ZookeeperCluster resource YAML file as input and generates bunch of secondary resources YAML files. The generated output look like the following:
>tree ZookeeperCluster/
ZookeeperCluster/
├── client
│ └── Service.yaml
├── config
│ └── ConfigMap.yaml
├── headless
│ └── Service.yaml
├── pdb
│ └── PodDisruptionBudget.yaml
└── zk
└── StatefulSet.yaml
When you build Operator, the Exporter is built along with it.
make build-go - will build both Operator as well as Exporter.
Just run zookeeper-exporter binary with -help option. It will guide you to input ZookeeperCluster YAML file. There are couple of more options to specify.
Example: ./zookeeper-exporter -i ./ZookeeperCluster.yaml -o .