The document discusses the MySQL Operator for Kubernetes, which allows users to run MySQL clusters on Kubernetes. It provides an overview of how the operator works using the Kopf framework to create Kubernetes custom resources and controllers. It describes how the operator creates deployments, services, and other resources to set up MySQL servers in a stateful set, a replica set for routers, and monitoring. The document also provides instructions for installing the MySQL Operator using Kubernetes manifests or Helm.

1. Fault Tolerance
Exploration of MySQL Operator
for Kubernetes in Python
October 29, 2022
Ivan Ma
MySQL Master principal Solution Engineer

2. The following is intended to outline our general product direction.
It is intended for information purposes only, and may not be
incorporated into any contract. It is not a commitment to deliver
any material, code, or functionality, and should not be relied upon
in making purchasing decisions. The development, release,
timing, and pricing of any features or functionality described for
Oracle’s products may change and remains at the sole discretion
of Oracle Corporation.
Safe harbor statement
2

3. MySQL Operator for Kubernetes
• Pod [ mysqloperator ]
• Dockerfile [ building the image ]
• https://github.com/mysql/mysql-operator/blob/trunk/docker-build/Dockerfile
• Installed with MySQL Shell
• mysqloperator package for Python
• COPY mysqloperator/ /usr/lib/mysqlsh/python-packages/mysqloperator
• Kopf
• Framework to build Kubernetes operators in Python
• https://kopf.readthedocs.io/en/stable/architecture/

4. kopf operator creation
• Manual Execution
• pip3 install kopf
• Create CRD
• Create the myoperator.py
• “Manually”
• kopf run myoprator.py
• Creating the resource object
External Reference Only : https://blog.baeke.info/2020/01/26/writing-a-kubernetes-
operator-with-kopf/

5. CRD - example
apiVersion: apiextensions.k8s.io/v1
kind: CustomResourceDefinition
metadata:
name: demowebs.mygroup.info
spec:
scope: Namespaced
group: mygroup.info
versions:
- name: v1
served: true
storage: true
schema:
openAPIV3Schema:
type: object
properties:
spec:
type: object
properties:
gitRepo:
type: string
replicas:
type: integer
names:
kind: DemoWeb
plural: demowebs
singular: demoweb
shortNames:
- dweb

6. Creation of crd
# kubectl apply –f demowebs-crd.yaml
# kubectl get crd demowebs.mygroup.info
NAME CREATED AT
demowebs.mygroup.info 2022-10-21T04:05:00Z

7. Creating the Resource Object
kubectl create ns mydemo
cat << EOF |kubectl apply -n mydemo -f -
apiVersion: mygroup.info/v1
kind: DemoWeb
metadata:
name: mydemoweb
spec:
replicas: 2
gitRepo: "https://github.com/ivanxma/staticweb.git"
EOF

8. Creation of the myoperator.py
The operator to be executed by “kopf”
import kopf
import kubernetes.client
from kubernetes.client.rest import ApiException
import yaml
@kopf.on.create('mygroup.info', 'v1', 'demowebs')
def create_fn(spec, **kwargs):
name = kwargs["body"]["metadata"]["name"]
print("Name is %sn" % name)
# Create the deployment spec
doc = yaml.safe_load(f"""
apiVersion: apps/v1
kind: Deployment
metadata:
name: {name}-deployment
labels:
app: {name}
spec:
replicas: {spec.get('replicas', 1)}
selector:
matchLabels:
app: {name}
template:
metadata:
labels:
app: {name}
spec:
containers:
- name: nginx
image: nginx
ports:
- containerPort: 80
volumeMounts:
- name: workdir
mountPath: /usr/share/nginx/html
initContainers:
- name: install
image: alpine/git
command:
- git
- clone
- {spec.get('gitrepo', 'https://github.com/ivanxma/staticweb.git')}
- /work-dir
volumeMounts:
- name: workdir
mountPath: /work-dir
dnsPolicy: Default
volumes:
- name: workdir
emptyDir: {{}}
""")
# Adopt the Yaml and Apply
kopf.adopt(doc)
api = kubernetes.client.AppsV1Api()
try:
depl =
api.create_namespaced_deployment(namespace=doc['metadata']['nam
espace'], body=doc)
except ApiException as e:
print("Exception when calling AppsV1Api-
>create_namespaced_deployment: %sn" % e)
CRD : kind : DemoWeb
spec properties : replicas, gitRepos

9. The resource object
• The resource object DemoWeb [kind] is created - A definition ONLY
• What next : to execute the operator
• # kopf run --namespace=”<namespaces>” myoperator.py

10. How the MySQL Operator works
https://github.com/mysql/mysql-operator/blob/trunk/mysqloperator/controller/innodbcluster/operator_cluster.py
• @kopf.on.create(consts.GROUP, consts.VERSION, consts.INNODBCLUSTER_PLURAL)
• 1. prepare_initconf è2. prepare_secrets
• 3. prepare_router_secrets è 4. prepare_cluster_service
• 5. prepare-service_account è 6. prepare_role_binding
• 7. prepare_cluster_stateful_set è 8. prepare_cluster_pod_disruption_budget
• 9. prepare_router_service è 10 prepare_router_deployment
• 11 prepare_backup_secrets è
• Finally : set cluster status è online instance = 0, status as PENDING
• @kopf.on.delete(consts.GROUP, consts.VERSION,consts.INNODBCLUSTER_PLURAL)
• @kopf.on.filed(consts.GROUP, const.VERSION, consts.INNODBCLUSTER_PLURAL, filed=“….”)
• @kopf.on.field(consts.GROUP, consts.VERSION, consts.INNODBCLUSTER_PLURAL,field="spec.version") (spec.router.version)
• cluster_ctl.on_server_version_change(new)
• @kopf.on.create("", "v1", "pods",labels={"component": "mysqld"})
• @kopf.on.event ("", "v1", "pods",labels={"component": "mysqld"})
• @kopf.on.delete("", "v1", "pods", labels={"component": "mysqld"})

11. MySQL Operator
Creation of Innodb Cluster in K8s
11

12. mysql-2
mysql-1
mysql-0
Kubernetes Environment
MySQL InnoDB Cluster
application-0
apps-0
app-0 app-1
LB
Container
Bins Libs
App
Container
Bins Libs
App
mysql-mon-0
mem-0
Container
Bins Libs
MySQL
Monitor
mysql-innodb-cluster-0
mysql-routers [Replicaset]
router-x
Container
Bins Libs
MySQL
Router
router-y
Container
Bins Libs
MySQL
Router
K8s
Service
mysql-servers [Statefulset]
mysql-0
Container
Bins Libs
MySQL
mysql-1
Container
Bins Libs
MySQL
mysql-2
Container
Bins Libs
MySQL
GR GR
prim
ary
router-z
Container
Bins Libs
MySQL
Router
Deployment
pod
Kopf framework
mysql-operator

13. Manifest Installation
MySQL Operator for Kubernetes
• https://github.com/mysql/mysql-operator
• https://dev.mysql.com/doc/mysql-operator/en/mysql-operator-installation-kubectl.html
• 1- Apply Custom Resource Definition:
• $> kubectl apply -f https://raw.githubusercontent.com/mysql/mysql-operator/trunk/deploy/deploy-
crds.yaml
• 2- Deploy operator
• $> kubectl apply -f https://raw.githubusercontent.com/mysql/mysql-operator/trunk/deploy/deploy-
operator.yaml
• 3- Describe operator
• $> kubectl get deployment mysql-operator --namespace mysql-operator

14. Helm installation
MySQL Operator for Kubernetes
• https://dev.mysql.com/doc/mysql-operator/en/mysql-operator-installation-helm.html
• $> helm repo add mysql-operator https://mysql.github.io/mysql-operator/
• $> helm repo update
• $> helm install my-mysql-operator mysql-operator/mysql-operator --namespace mysql-operator --create-
namespace

15. Connecting to InnoDB Cluster with MySQL Operator Image
$> kubectl run --rm -it myshell -n <the ns> --image=mysql/mysql-operator – mysqlsh
If you don't see a command prompt, try pressing enter. MySQL JS >

16. More on Operations
MySQL Operator for Kubernetes
• Checking Innodb cluster status:
• kubectl get innodbcluster --watch –n <namespace>
• Retrieve IP address of cluster:
• kubectl get service mycluster –n <namespace>
• Describe the storage (PVC) for a MySQL server:
• kubectl describe pvc datadir-mycluster-[0|1|2|…] –n <namespace>
• Exposing ports (applications outside of Kubernetes):
• kubectl port-forward service/mycluster mysql –n <namespace>
• kubectl expose rs mycluster-router --port=6446 --target-port=6446 --type=LoadBalancer -
-name mycluster-lb –n <namespace>

17. Thank you