Can i run mysql on kubernetes?

This tutorial shows detailed steps of deploying MySQL on Kubernetes. I’ll be using minikube here to demonstrate Kubernetes MySQL examples.

We all know the big importance of data persistence and almost, all our applications rely hugely on some sort of Database Management Systems (DBMS). Setting up a DBMS on Kubernetes helps the DevOps team and Database administrators leverage and scale the Database easily.

Prepare the environment

Follow this tutorial you need to have Minikube installed on your Ubuntu Linux.

You can verify whether the Minikube has been successfully up and running by the following command:

$ minikube status

Output:

minikube type: Control Plane host: Running kubelet: Running apiserver: Running kubeconfig: Configured

Create Secret for MySQL

Kubernetes uses Secret to store and manage sensitive information such as passwords, ssh keys and OAuth tokens. In this tutorial, we use base64 encoded to store 'MYSQL_ROOT_PASSWORD'. For example:

$ echo -n 'admin' | base64

Output:

YWRtaW4=

Create a mysql-secret.yaml file for MySQL that will be mapped as an environment variable as follows:

apiVersion: v1 kind: Secret metadata: name: mysql-pass type: Opaque data: password: YWRtaW4=

Apply the manifest:

$ kubectl create -f mysql-secret.yaml secret/mysql-pass created

Verify that the Secret has just been created successfully:

$ kubectl get secrets NAME TYPE DATA AGE default-token-l7t7b kubernetes.io/service-account-token 3 4h24m mysql-pass Opaque 1 1m

Create the mysql-pod.yaml file to deploy MySQL pod on Kubernetes cluster:

apiVersion: v1 kind: Pod metadata: name: k8s-mysql labels: name: lbl-k8s-mysql spec: containers: - name: mysql image: mysql:latest env: - name: MYSQL_ROOT_PASSWORD valueFrom: secretKeyRef: name: mysql-pass key: password ports: - name: mysql containerPort: 3306 protocol: TCP volumeMounts: - name: k8s-mysql-storage mountPath: /var/lib/mysql volumes: - name: k8s-mysql-storage emptyDir: {}

Apply the manifest file:

$ kubectl create -f mysql-pod.yaml pod/k8s-mysql created

Verify that the pod is running:

$ kubectl get pod NAME READY STATUS RESTARTS AGE k8s-mysql 1/1 Running 0 30s

Now, we can connect to the k8s-mysql pod:

$ kubectl exec k8s-mysql -it -- bash root@k8s-mysql:/# echo $MYSQL_ROOT_PASSWORD admin root@k8s-mysql:/# mysql --user=root --password=$MYSQL_ROOT_PASSWORD mysql: [Warning] Using a password on the command line interface can be insecure. Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 11 Server version: 8.0.22 MySQL Community Server - GPL Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql> show databases; +--------------------+ | Database | +--------------------+ | information_schema | | mysql | | performance_schema | | sys | +--------------------+ 4 rows in set (0.00 sec) mysql>

Kubernetes use Service to expose pods to other pods or external systems. We will use the following manifest file mysql-service.yaml to make the k8s-mysql pod be reachable:

apiVersion: v1 kind: Service metadata: name: mysql-service labels: name: lbl-k8s-mysql spec: ports: - port: 3306 selector: name: lbl-k8s-mysql type: ClusterIP

Apply the manifest to create the service:

$ kubectl create -f mysql-service.yaml service/mysql-service created

Verify that the service has been successfully created:

$ kubectl get svc NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE kubernetes ClusterIP 10.96.0.1 443/TCP 5h4m mysql-service ClusterIP 10.110.22.182 3306/TCP 30s

Creating a NodeJS Api to hit mysql

In order to be able to connect to mysql from an other pod we need to have the IP address of our pod which can be done using:

$ kubectl get pod k8s-mysql -o template --template={{.status.podIP}} 172.17.0.5

Alright, now I’m going to create a sample NodeJS app, to store a set of messages in database MESSAGES table, the app will have two endpoints:

• '/ping': to check the server health
• '/msg-api/all': to get all the stored messages

To keep things simple... the table will have only one column called TEXT.

First thing first, node app:

// api.js -> endpoints goes here

var express = require('express') var mysql = require('mysql') var Router = express.Router(); var ConnPool = mysql.createPool({ host: '172.17.0.5', user: 'root', password: 'admin', database: 'k8smysqldb' }) // create database and MESSAGE table if not exist ConnPool.query('CREATE DATABASE IF NOT EXISTS k8smysqldb', function (err) { if (err) throw Error('\n\t **** error creating database **** ' + err) console.log('\n\t ==== database k8smysqldb created !! ====') ConnPool.query('USE k8smysqldb', function (err) { if (err) throw Error('\n\t **** error using database **** ' + err); console.log('\n\t ==== database k8smysqldb switched !! ====') ConnPool.query('CREATE TABLE IF NOT EXISTS messages(' + 'id INT NOT NULL AUTO_INCREMENT,' + 'PRIMARY KEY(id),' + 'text VARCHAR(100)' + ')', function (err) { if (err) throw Error('\n\t **** error creating table **** ' + err); }) }) }) /** * /all */ Router.get('/all', function (req, res) { ConnPool.getConnection(function (errConn, conn) { if (errConn) throw Error('error get connection : ' + errConn) conn.query('SELECT * FROM messages', function (errSelect, rows) { if (errSelect) throw Error('error selecting messages : ' + errSelect) res.writeHead(200, { 'Content-Type': 'application/json' }); var result = { success: true, rows: rows.length, } res.write(JSON.stringify(rows)); res.end(); }) }) }) module.exports = Router

// server.js -> fire expressjs server

var express = require('express') var msgApi = require('./api') var app = express() app.use('/msg-api', msgApi) app.get('/ping', function (req, res) { res.write("hello there! I m up and running!"); res.end(); }) app.listen(8080, function () { console.log('\n\t ==== Message API listening on 8080! ====') })

// Dockerfile -> bundle docker image for our app

FROM node:latest RUN mkdir -p /usr/src/app WORKDIR /usr/src/app COPY package.json /usr/src/app/package.json RUN npm i COPY . /usr/src/app/ EXPOSE 8080 CMD [ "node", "server.js" ]

Now we can build our docker images from the Dockerfile:

$ docker build -t linoxide/msg-api:v0.0.3 . --no-cache=true Sending build context to Docker daemon 5.12kB Step 1/8 : FROM node:latest ---> 2d840844f8e7 Step 2/8 : RUN mkdir -p /usr/src/app ---> Using cache ---> 1c29cda3dcd8 Step 3/8 : WORKDIR /usr/src/app ...

And push the built image to Docker Hub:

$ docker push linoxide/msg-api:v0.0.3 The push refers to a repository [docker.io/linoxide/msg-api] c4477a160652: Pushed 32c1bac97782: Pushed 3d629e3d2e5a: Pushed ... v1: digest: sha256:dba64e7ff64561f4af866fbbb657555cad7621688c7f312975943f5baf89efa2 size: 2628

Now we can create a pod of our NodeJS app, the below spec file msg-api-pod.yaml

apiVersion: v1 kind: Pod metadata: name: k8s-msg-api labels: name: lbl-msg-api spec: containers: - name: msg-api image: linoxide/msg-api:v0.0.1 ports: - name: msg-api

Apply the manifest:

$ kubectl create -f msg-api-pod.yaml pod/k8s-msg-api created

Make sure that the pod is running by checking the status:

$ kubectl get pod NAME          READY     STATUS    RESTARTS   AGE k8s-msg-api   1/1       Running   0          22s k8s-mysql     1/1       Running   0          1h

At this level we need to expose the created pod so that can access it from outside. This time I will do it using only command line rather a spec file:

$ kubectl expose pod k8s-msg-api --port=8080 --name=k8s-srv-msg-api --type=NodePort service/k8s-srv-msg-api exposed

Getting data from mysql database using nodejs api

At this level, I need to point out some important stuff, in order understand all the pieces, let’s first, summarize what we have done until now, so far, we have created a MySQL pod and we have exposed it through a service to make it accessible for other pods, second, we have created a sample nodejs app, we called it a messaging api, so that we can use it to hit the MySQL pod; similarly, to be able to access the messaging API we need to expose it through a service, I hope everything is clear until here!

Now the question is how can we call our messaging api from outside of our cluster mainly minikube? To do so, we need the IP address of our node, as I'm using minikube which create only one node so, the IP address is resolved, is the minikube ip address itself, just run:

$ minikube ip 192.168.99.100

And what about the port? Well good question! let’s describe our messaging api service to check that out:

$ kubectl describe service k8s-srv-msg-api Name:           k8s-srv-msg-api Namespace:      default Labels:         name=lbl-msg-api Selector:       name=lbl-msg-api Type:           NodePort IP:         10.0.0.170 Port:           <unset> 8080/TCP NodePort:       <unset> 30887/TCP Endpoints:      172.17.0.6:8080 Session Affinity:   None No events.

So we have Port which is the port of our messaging API service. NodePort is the port on which the exposed service is available (accessible) i.e., the service is available on NodeIP:NodePort

Let’s try that out:

$ curl 192.168.99.100:30887/ping hello there! I m up and running!% $ curl 192.168.99.100:30887/msg-api/all []%

Very nice, so far we are able to hit our MySQL database, let’s insert some data into our database using terminal.

$ kubectl exec k8s-mysql -it -- bash root@k8s-mysql:/# mysql --user=root --password=$MYSQL_ROOT_PASSWORD mysql: [Warning] Using a password on the command line interface can be insecure. ... mysql> use k8smysqldb; Reading table information for completion of table and column names You can turn off this feature to get a quicker startup with -A Database changed mysql> show tables; +----------------------+ | Tables_in_k8smysqldb | +----------------------+ | messages             | +----------------------+ 1 row in set (0.01 sec) mysql> insert into messages(text) values ('this is the first msg!'); Query OK, 1 row affected (0.01 sec) mysql> insert into messages(text) values ('this is the second msg!'); Query OK, 1 row affected (0.01 sec)

Let’s get this data through our nodejs API using curl:

$ curl 192.168.99.100:30887/msg-api/all [{"id":1,"text":"this is the first msg!"},{"id":2,"text":"this is the second msg!"}]%

Conclusion

Containerizing the MySQL database and running DBMS on a Kubernetes cluster brings a lot of benefits to DevOps team, such as portability across environments, start/stop and update easier and having better security due to the services are isolated.

Thanks for reading and please leave your suggestion in the below comment section.

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