MySQL router in kubernetes as a service - mysql

Question

I want to deploy MySQL-router in Kubernetes working as a service.
My plan..
Deploy MySQL-router inside k8 and expose MySQL-router as a service using LoadBalancer (MetalLB)
Applications running inside k8 sees mysql-router service as its database.
MySQL-router sends application data to outside InnoDB cluster.
I tried to deploy using:
apiVersion: apps/v1
kind: Deployment
metadata:
name: mysql-router
namespace: mysql-router
spec:
replicas: 1
selector:
matchLabels:
app: mysql-router
template:
metadata:
labels:
app: mysql-router
version: v1
spec:
containers:
- name: mysql-router
image: mysql/mysql-router
env:
- name: MYSQL_HOST
value: "192.168.123.130"
- name: MYSQL_PORT
value: "3306"
- name: MYSQL_USER
value: "root"
- name: MYSQL_PASSWORD
value: "root#123"
imagePullPolicy: Always
ports:
- containerPort: 6446
192.168.123.130 is MySQL cluster Master IP.
apiVersion: v1
kind: Service
metadata:
name: mysql-router-service
namespace: mysql-router
labels:
app: mysql-router
spec:
selector:
app: mysql-router
ports:
- protocol: TCP
port: 6446
type: LoadBalancer
loadBalancerIP: 192.168.123.123
When I check mysql-router container logs, I see something like this:
Waiting for mysql server 192.168.123.130 (0/12)
Waiting for mysql server 192.168.123.130 (1/12)
Waiting for mysql server 192.168.123.130 (2/12)
....
After setting my external MySQL cluster info in deployment, I get following errors:
Successfully contacted mysql server at 192.168.123.130. Checking for cluster state.
Can not connect to database. Exiting.
I can not deploy mysql-router without specifying MYSQL_HOST. What am I missing here?
My ideal deployment

Answer 1

Of course you have to provide the MySQL Host. You could doing this with k8s DNS which setup with in the services.
MySQL Router is middleware that provides transparent routing between your application and any backend MySQL Servers. It can be used for a wide variety of use cases, such as providing high availability and scalability by effectively routing database traffic to appropriate backend MySQL Servers.
Examples
For examples below i use dynamic volume provisioning for data using openebs-hostpath And using StatefulSet for the MySQL Server.
Deployment
MySQL Router :
apiVersion: apps/v1
kind: Deployment
metadata:
name: mysql-router
namespace: mysql-router
spec:
replicas: 1
selector:
matchLabels:
app: mysql-router
template:
metadata:
labels:
app: mysql-router
version: v1
spec:
containers:
- name: mysql-router
image: mysql/mysql-router
env:
- name: MYSQL_HOST
value: "mariadb-galera.galera-cluster"
- name: MYSQL_PORT
value: "3306"
- name: MYSQL_USER
value: "root"
- name: MYSQL_PASSWORD
value: "root#123"
imagePullPolicy: Always
ports:
- containerPort: 3306
MySQL Server
apiVersion: apps/v1
kind: StatefulSet
metadata:
namespace: galera-cluster
name: mariadb-galera
spec:
podManagementPolicy: OrderedReady
replicas: 1
selector:
matchLabels:
app: mariadb-galera
serviceName: mariadb-galera
template:
metadata:
labels:
app: mariadb-galera
spec:
restartPolicy: Always
securityContext:
fsGroup: 1001
runAsUser: 1001
containers:
- command:
- bash
- -ec
- |
# Bootstrap from the indicated node
NODE_ID="${MY_POD_NAME#"mariadb-galera-"}"
if [[ "$NODE_ID" -eq "0" ]]; then
export MARIADB_GALERA_CLUSTER_BOOTSTRAP=yes
export MARIADB_GALERA_FORCE_SAFETOBOOTSTRAP=no
fi
exec /opt/bitnami/scripts/mariadb-galera/entrypoint.sh /opt/bitnami/scripts/mariadb-galera/run.sh
env:
- name: MY_POD_NAME
valueFrom:
fieldRef:
apiVersion: v1
fieldPath: metadata.name
- name: BITNAMI_DEBUG
value: "false"
- name: MARIADB_GALERA_CLUSTER_NAME
value: galera
- name: MARIADB_GALERA_CLUSTER_ADDRESS
value: gcomm://mariadb-galera.galera-cluster
- name: MARIADB_ROOT_PASSWORD
value: root#123
- name: MARIADB_DATABASE
value: my_database
- name: MARIADB_GALERA_MARIABACKUP_USER
value: mariabackup
- name: MARIADB_GALERA_MARIABACKUP_PASSWORD
value: root#123
- name: MARIADB_ENABLE_LDAP
value: "no"
- name: MARIADB_ENABLE_TLS
value: "no"
image: docker.io/bitnami/mariadb-galera:10.4.13-debian-10-r23
imagePullPolicy: IfNotPresent
livenessProbe:
exec:
command:
- bash
- -ec
- |
exec mysqladmin status -uroot -p$MARIADB_ROOT_PASSWORD
failureThreshold: 3
initialDelaySeconds: 120
periodSeconds: 10
successThreshold: 1
timeoutSeconds: 1
name: mariadb-galera
ports:
- containerPort: 3306
name: mysql
protocol: TCP
- containerPort: 4567
name: galera
protocol: TCP
- containerPort: 4568
name: ist
protocol: TCP
- containerPort: 4444
name: sst
protocol: TCP
readinessProbe:
exec:
command:
- bash
- -ec
- |
exec mysqladmin status -uroot -p$MARIADB_ROOT_PASSWORD
failureThreshold: 3
initialDelaySeconds: 30
periodSeconds: 10
successThreshold: 1
timeoutSeconds: 1
volumeMounts:
- mountPath: /opt/bitnami/mariadb/.bootstrap
name: previous-boot
- mountPath: /bitnami/mariadb
name: data
- mountPath: /opt/bitnami/mariadb/conf
name: mariadb-galera-config
volumes:
- emptyDir: {}
name: previous-boot
- configMap:
defaultMode: 420
name: my.cnf
name: mariadb-galera-config
volumeClaimTemplates:
- apiVersion: v1
metadata:
name: data
spec:
storageClassName: openebs-hostpath
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 20Gi
Services
MySQL Router Service
apiVersion: v1
kind: Service
metadata:
name: mysql-router-service
namespace: mysql-router
labels:
app: mysql-router
spec:
selector:
app: mysql-router
ports:
- protocol: TCP
port: 3306
type: LoadBalancer
loadBalancerIP: 192.168.123.123
MySQL Service
apiVersion: v1
kind: Service
metadata:
namespace: galera-cluster
name: mariadb-galera
labels:
app: mariadb-galera
spec:
type: ClusterIP
ports:
- name: mysql
port: 3306
selector:
app: mariadb-galera
---
apiVersion: v1
kind: Service
metadata:
namespace: galera-cluster
name: mariadb-galera-headless
labels:
app: mariadb-galera
spec:
type: ClusterIP
ports:
- name: galera
port: 4567
- name: ist
port: 4568
- name: sst
port: 4444
selector:
app: mariadb-galera

Answer 2

What you need its #1 communication from App1-x to Mysql router and #2 a VIP/LB from MysqlRoutere to external mysql instances.
Well start with #2 configuration of Mysql instances VIP. You will need a service without selector.
apiVersion: v1
kind: Service
metadata:
name: mysql-service
spec:
ports:
- name: mysql
port: 3306
protocol: TCP
targetPort: 3306
sessionAffinity: None
type: ClusterIP
---
apiVersion: v1
kind: Endpoints
metadata:
name: mysql-service
subsets:
- addresses:
- ip: 192.168.123.130
- ip: 192.168.123.131
- ip: 192.168.123.132
ports:
- name: mysql
port: 3306
protocol: TCP
You don't need LoadBalancer cuz you will connect only inside cluster. So, use ClusterIp instead.
#1 Create MysqlRouter deployment.
apiVersion: apps/v1
kind: Deployment
metadata:
name: mysql-router
namespace: mysql-router
spec:
replicas: 1
selector:
matchLabels:
app: mysql-router
template:
metadata:
labels:
app: mysql-router
version: v1
spec:
containers:
- name: mysql-router
image: mysql/mysql-router
env:
- name: MYSQL_HOST
value: "mysql-service"
- name: MYSQL_PORT
value: "3306"
- name: MYSQL_USER
value: "root"
- name: MYSQL_PASSWORD
value: "root#123"
imagePullPolicy: Always
ports:
- containerPort: 6446
To connect to external MySQL instances trough VIP/ClusterIP use mysql-service service and if deployment and service is in same namespace use mysql-service as hostname or put there a CLusterIP from kubectl get service mysql-service
apiVersion: v1
kind: Service
metadata:
name: mysql-router-service
namespace: mysql-router
labels:
app: mysql-router
spec:
selector:
app: mysql-router
ports:
- name: mysql
port: 6446
protocol: TCP
targetPort: 6446
type: ClusterIP
You can connect within kubernetes cluster to mysql-router-service hostname in same namespace and outside namespace to mysql-router-service.namespace.svc or outside kubernetes cluster use NodePort or LoadBalancer.