如何编辑存在于 kubernetes mysql 容器中的 my.cnf 文件？

Question

I have created mysql container inside pod by giving mount path as /var/lib/mysql. When I try to create container with this mountPath getting below error.

2022-12-16T07:13:59.139528Z 0 [ERROR] [MY-010457] [Server] --initialize specified but the data directory has files in it. Aborting.

2022-12-16T07:13:59.139537Z 0 [ERROR] [MY-013236] [Server] The designated data directory /var/lib/mysql/ is unusable. You can remove all files that the server added to it.

So I decided to change the data directory path in my.cnf to give it to empty folder such as /var/lib/dbmysql.

But I am not able to change the my.cnf file inside the mysql container.

Steps that I followed:

1. kubectl exec -i -t pod-name --container container-name -- /bin/bash

2. In the bash trying to change the file using

   a) bash-4.2$ cat > /etc/my.cnf

    bash: /etc/my.cnf: Permission denied

   b) vim /etc/my.cnf

    bash: vim: command not found

same for nano and vi

c) Also tried to install vim using apt-get as well as apk update but getting same error command not found.

Please guide me !!

Answer 1

One possibility is changing the volume path /var/lib/mysql , if you want to use the same path then you can try the below recommended way also.

To run a single-instance stateful MySQL application in Kubernetes using a PV and a Deployment refer to Run a Single-Instance Stateful Application .

Try by deploying everything again and also check if the MySQL image you are using doesn't have any issues and runs without PVC first.

For example, this YAML file describes a Deployment that runs MySQL and references the PVC. The file defines a volume mount for /var/lib/mysql, and then creates a PVC that looks for a 20G volume. This claim is satisfied by any existing volume that meets the requirements, or by a dynamic provisioner.

Before applying, update necessary changes like an image of MySQL.

apiVersion: v1
kind: PersistentVolume
metadata:
  name: mysql-pv-volume
  labels:
    type: local
spec:
  capacity:
    storage: 20Gi
  accessModes:
    - ReadWriteOnce
  hostPath:
    path: "/mnt/data"
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mysql-pv-claim
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 20Gi

And Deployment & Service like..

apiVersion: v1
kind: Service
metadata:
  name: mysql
spec:
  ports:
  - port: 3306
  selector:
    app: mysql
  clusterIP: None
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: mysql
spec:
  selector:
    matchLabels:
      app: mysql
  strategy:
    type: Recreate
  template:
    metadata:
      labels:
        app: mysql
    spec:
      containers:
      - image: mysql:5.6
        name: mysql
        env:
          # Use secret in real usage
        - name: MYSQL_ROOT_PASSWORD
          value: password
        ports:
        - containerPort: 3306
          name: mysql
        volumeMounts:
        - name: mysql-persistent-storage
          mountPath: /var/lib/mysql
      volumes:
      - name: mysql-persistent-storage
        persistentVolumeClaim:
          claimName: mysql-pv-claim