Cass Operator

The DataStax Kubernetes Operator for Apache Cassandra®

Getting Started

Quick start:

# *** This is for GKE Regular Channel - k8s 1.16 -> Adjust based on your cloud or storage options
kubectl create -f https://raw.githubusercontent.com/datastax/cass-operator/v1.6.0/docs/user/cass-operator-manifests-v1.16.yaml
kubectl create -f https://raw.githubusercontent.com/datastax/cass-operator/v1.6.0/operator/k8s-flavors/gke/storage.yaml
kubectl -n cass-operator create -f https://raw.githubusercontent.com/datastax/cass-operator/v1.6.0/operator/example-cassdc-yaml/cassandra-3.11.x/example-cassdc-minimal.yaml

Loading the operator

Installing the Cass Operator itself is straightforward. We have provided manifests for each Kubernetes version from 1.15 through 1.19. Apply the relevant manifest to your cluster as follows:

K8S_VER=v1.16
kubectl apply -f https://raw.githubusercontent.com/datastax/cass-operator/v1.6.0/docs/user/cass-operator-manifests-$K8S_VER.yaml

Note that since the manifest will install a Custom Resource Definition, the user running the above command will need cluster-admin privileges.

This will deploy the operator, along with any requisite resources such as Role, RoleBinding, etc., to the cass-operator namespace. You can check to see if the operator is ready as follows:

$ kubectl -n cass-operator get pods --selector name=cass-operator
NAME                             READY   STATUS    RESTARTS   AGE
cass-operator-555577b9f8-zgx6j   1/1     Running   0          25h

Creating a storage class

You will need to create an appropriate storage class which will define the type of storage to use for Cassandra nodes in a cluster. For example, here is a storage class for using SSDs in GKE, which you can also find at operator/deploy/k8s-flavors/gke/storage.yaml:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: server-storage
provisioner: kubernetes.io/gce-pd
parameters:
  type: pd-ssd
  replication-type: none
volumeBindingMode: WaitForFirstConsumer
reclaimPolicy: Delete

Apply the above as follows:

kubectl apply -f https://raw.githubusercontent.com/datastax/cass-operator/v1.6.0/operator/k8s-flavors/gke/storage.yaml

Creating a CassandraDatacenter

The following resource defines a Cassandra 3.11.7 datacenter with 3 nodes on one rack, which you can also find at operator/example-cassdc-yaml/cassandra-3.11.x/example-cassdc-minimal.yaml:

apiVersion: cassandra.datastax.com/v1beta1
kind: CassandraDatacenter
metadata:
  name: dc1
spec:
  clusterName: cluster1
  serverType: cassandra
  serverVersion: 3.11.7
  managementApiAuth:
    insecure: {}
  size: 3
  storageConfig:
    cassandraDataVolumeClaimSpec:
      storageClassName: server-storage
      accessModes:
      - ReadWriteOnce
      resources:
        requests:
          storage: 5Gi
  config:
    cassandra-yaml:
      authenticator: org.apache.cassandra.auth.PasswordAuthenticator
      authorizer: org.apache.cassandra.auth.CassandraAuthorizer
      role_manager: org.apache.cassandra.auth.CassandraRoleManager
    jvm-options:
      initial_heap_size: 800M
      max_heap_size: 800M

Apply the above as follows:

kubectl -n cass-operator apply -f https://raw.githubusercontent.com/datastax/cass-operator/v1.6.0/operator/example-cassdc-yaml/cassandra-3.11.x/example-cassdc-minimal.yaml

You can check the status of pods in the Cassandra cluster as follows:

$ kubectl -n cass-operator get pods --selector cassandra.datastax.com/cluster=cluster1
NAME                         READY   STATUS    RESTARTS   AGE
cluster1-dc1-default-sts-0   2/2     Running   0          26h
cluster1-dc1-default-sts-1   2/2     Running   0          26h
cluster1-dc1-default-sts-2   2/2     Running   0          26h

You can check to see the current progress of bringing the Cassandra datacenter online by checking the cassandraOperatorProgress field of the CassandraDatacenter's status sub-resource as follows:

$ kubectl -n cass-operator get cassdc/dc1 -o "jsonpath={.status.cassandraOperatorProgress}"
Ready

(cassdc and cassdcs are supported short forms of CassandraDatacenter.)

A value of "Ready", as above, means the operator has finished setting up the Cassandra datacenter.

You can also check the Cassandra cluster status using nodetool by invoking it on one of the pods in the Cluster as follows:

$ kubectl -n cass-operator exec -it -c cassandra cluster1-dc1-default-sts-0 -- nodetool status
Datacenter: dc1
===============
Status=Up/Down
|/ State=Normal/Leaving/Joining/Moving/Stopped
--  Address         Load       Tokens       Owns (effective)  Host ID                               Rack
UN  10.233.105.125  224.82 KiB  1            65.4%             5e29b4c9-aa69-4d53-97f9-a3e26115e625  r1
UN  10.233.92.96    186.48 KiB  1            61.6%             b119eae5-2ff4-4b06-b20b-c492474e59a6  r1
UN  10.233.90.54    205.1 KiB   1            73.1%             0a96e814-dcf6-48b9-a2ca-663686c8a495  r1

The operator creates a secure Cassandra cluster by default, with a new superuser (not the traditional cassandra user) and a random password. You can get those out of a Kubernetes secret and use them to log into your Cassandra cluster for the first time. For example:

$ # get CASS_USER and CASS_PASS variables into the current shell
$ CASS_USER=$(kubectl -n cass-operator get secret cluster1-superuser -o json | jq -r '.data.username' | base64 --decode)
$ CASS_PASS=$(kubectl -n cass-operator get secret cluster1-superuser -o json | jq -r '.data.password' | base64 --decode)
$ kubectl -n cass-operator exec -ti cluster1-dc1-default-sts-0 -c cassandra -- sh -c "cqlsh -u '$CASS_USER' -p '$CASS_PASS'"

Connected to cluster1 at 127.0.0.1:9042.
[cqlsh 5.0.1 | Cassandra 3.11.6 | CQL spec 3.4.4 | Native protocol v4]
Use HELP for help.

[email protected]> select * from system.peers;

 peer      | data_center | host_id                              | preferred_ip | rack    | release_version | rpc_address | schema_version                       | tokens
-----------+-------------+--------------------------------------+--------------+---------+-----------------+-------------+--------------------------------------+--------------------------
 10.28.0.4 |         dc1 | 4bf5e110-6c19-440e-9d97-c013948f007c |         null | default |          3.11.6 |   10.28.0.4 | e84b6a60-24cf-30ca-9b58-452d92911703 | {'-7957039572378599263'}
 10.28.5.5 |         dc1 | 3e84b0f1-9c1e-4deb-b6f8-043731eaead4 |         null | default |          3.11.6 |   10.28.5.5 | e84b6a60-24cf-30ca-9b58-452d92911703 | {'-3984092431318102676'}

(2 rows)

(Optional) Loading the operator via Helm

Helm may be used to install the operator. Consider installing it from our Helm Charts repo

helm repo add datastax https://datastax.github.io/charts
helm repo update

# Helm 2
helm install datastax/cass-operator

# Helm 3
helm install cass-operator datastax/cass-operator

or via a local checkout

kubectl create namespace cass-operator-system
helm install --namespace=cass-operator-system cass-operator ./charts/cass-operator-chart

The following Helm default values may be overridden:

clusterWideInstall: false
serviceAccountName: cass-operator
clusterRoleName: cass-operator-cr
clusterRoleBindingName: cass-operator-crb
roleName: cass-operator
roleBindingName: cass-operator
webhookClusterRoleName: cass-operator-webhook
webhookClusterRoleBindingName: cass-operator-webhook
deploymentName: cass-operator
deploymentReplicas: 1
defaultImage: "datastax/cass-operator:1.6.0"
imagePullPolicy: IfNotPresent
imagePullSecret: ""

NOTE: roleName and roleBindingName will be used for a clusterRole and clusterRoleBinding if clusterWideInstall is set to true.

NOTE: Helm does not install a storage-class for the cassandra pods.

If clusterWideInstall is set to true, then the operator will be able to administer CassandraDatacenters in all namespaces of the kubernetes cluster. A namespace must still be provided because some of the kubernetes resources for the operator require one.

Example:

kubectl create namespace cass-operator-system
helm install --set clusterWideInstall=true --namespace=cass-operator-system cass-operator ./charts/cass-operator-chart

Using a custom Docker registry with the Helm Chart

A custom Docker registry may be used as the source of the operator Docker image. Before "helm install" is run, a Secret of type "docker-registry" should be created with the proper credentials.

Then the "imagePullSecret" helm value may be set to the name of the ImagePullSecret to cause the custom Docker registry to be used.

Custom Docker registry example: Github packages

Github Packages may be used as a custom Docker registry.

First, a Github personal access token must be created.

See:

https://docs.github.com/en/github/authenticating-to-github/creating-a-personal-access-token

Second, the access token will be used to create the Secret:

kubectl create secret docker-registry github-docker-registry --docker-username=USERNAME --docker-password=ACCESSTOKEN --docker-server docker.pkg.github.com

Replace USERNAME with the github username and ACCESSTOKEN with the personal access token.

Now we can run "helm install" with the override value for imagePullSecret. This is often used with an override value for image so that a specific tag can be chosen. Note that the image value should include the full path to the custom registry.

helm install --set image=docker.pkg.github.com/datastax/cass-operator/operator:latest-ubi --set imagePullSecrets=github-docker-registry cass-operator ./charts/cass-operator-chart

Features

• Proper token ring initialization, with only one node bootstrapping at a time
• Seed node management - one per rack, or three per datacenter, whichever is more
• Server configuration integrated into the CassandraDatacenter CRD
• Rolling reboot nodes by changing the CRD
• Store data in a rack-safe way - one replica per cloud AZ
• Scale up racks evenly with new nodes
• Scale down racks evenly by decommissioning existing nodes
• Replace dead/unrecoverable nodes
• Multi DC clusters (limited to one Kubernetes namespace)

All features are documented in the User Documentation.

Containers

The operator is comprised of the following container images working in concert:

• The operator, built from sources in the operator directory.
• The config builder init container, built from sources in datastax/cass-config-builder.
• Cassandra, built from datastax/management-api-for-apache-cassandra, with Cassandra 3.11.7 support, and experimental support for Cassandra 4.0-beta1.
• ... or DSE, built from datastax/docker-images.

Overriding properties of cass-operator created Containers

If the CassandraDatacenter specifies a podTemplateSpec field, then containers with specific names can be used to override default settings in containers that will be created by cass-operator.

Currently cass-operator will create an InitContainer with the name of "server-config-init". Normal Containers that will be created have the names "cassandra", "server-system-logger", and optionally "reaper".

In general, the values specified in this way by the user will override anything generated by cass-operator.

Of special note is that user-specified environment variables, ports, and volumes in the corresponding containers will be added to the values that cass-operator automatically generates for those containers.

apiVersion: cassandra.datastax.com/v1beta1
kind: CassandraDatacenter
metadata:
  name: dc1
spec:
  clusterName: cluster1
  serverType: cassandra
  serverVersion: 3.11.7
  managementApiAuth:
    insecure: {}
  size: 3
  podTemplateSpec:
    spec:
      initContainers:
        - name: "server-config-init"
          env:
          - name: "EXTRA_PARAM"
            value: "123"
      containers:
        - name: "cassandra"
          terminationMessagePath: "/dev/other-termination-log"
          terminationMessagePolicy: "File"
  storageConfig:
    cassandraDataVolumeClaimSpec:
      storageClassName: server-storage
      accessModes:
      - ReadWriteOnce
      resources:
        requests:
          storage: 5Gi
  config:
    cassandra-yaml:
      authenticator: org.apache.cassandra.auth.PasswordAuthenticator
      authorizer: org.apache.cassandra.auth.CassandraAuthorizer
      role_manager: org.apache.cassandra.auth.CassandraRoleManager
    jvm-options:
      initial_heap_size: 800M
      max_heap_size: 800M

Requirements

• Kubernetes cluster, 1.15 or newer.

Contributing

As of version 1.0, Cass Operator is maintained by a team at DataStax and it is part of what powers DataStax Astra. We would love for open source users to contribute bug reports, documentation updates, tests, and features.

Developer setup

Almost every build, test, or development task requires the following pre-requisites...

• Golang 1.14
• Docker, either the docker.io packages on Ubuntu, Docker Desktop for Mac, or your preferred docker distribution.
• mage: There are some tips for using mage in docs/developer/mage.md

Building

The operator uses mage for its build process.

Build the Operator Container Image

This build task will create the operator container image, building or rebuilding the binary from golang sources if necessary:

mage operator:buildDocker

Build the Operator Binary

If you wish to perform ONLY to the golang build or rebuild, without creating a container image:

mage operator:buildGo

Testing

mage operator:testGo

End-to-end Automated Testing

Run fully automated end-to-end tests...

mage integ:run

Docs about testing are here. These work against any k8s cluster with six or more worker nodes.

Manual Local Testing

There are a number of ways to run the operator, see the following docs for more information:

• k8s targets: A set of mage targets for automating a variety of tasks for several different supported k8s flavors. At the moment, we support KIND, k3d, and gke. These targets can setup and manage a local cluster in either KIND or k3d, and also a remote cluster in gke. Both KIND and k3d can simulate a k8s cluster with multiple worker nodes on a single physical machine, though it's necessary to dial down the database memory requests.

The user documentation also contains information on spinning up your first operator instance that is useful regardless of what Kubernetes distribution you're using to do so.

Not (Yet) Supported Features

• Cassandra:
  • Integrated data repair solution
  • Integrated backup and restore solution
• DSE:
  • Advanced Workloads, like Search / Graph / Analytics

Uninstall

This will destroy all of your data!

Delete your CassandraDatacenters first, otherwise Kubernetes will block deletion because we use a finalizer.

kubectl delete cassdcs --all-namespaces --all

Remove the operator Deployment, CRD, etc.

kubectl delete -f https://raw.githubusercontent.com/datastax/cass-operator/v1.6.0/docs/user/cass-operator-manifests-v1.16.yaml

Contacts

For development questions, please reach out on Gitter, or by opening an issue on GitHub.

For usage questions, please visit our Community Forums: https://community.datastax.com

License

Copyright DataStax, Inc.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.