Kubernetes Inject Env Variable with File in a Volume - mysql

Question

Just for training purpose, I'm trying to inject those env variables with this ConfigMap in my Wordpress and Mysql app by using a File with a Volume.
---
apiVersion: v1
kind: ConfigMap
metadata:
name: wordpress-mysql
namespace: ex2
data:
wordpress.conf: |
WORDPRESS_DB_HOST mysql
WORDPRESS_DB_USER admin
WORDPRESS_DB_PASSWORD "1234"
WORDPRESS_DB_NAME wordpress
WORDPRESS_DB_PREFIX wp_
mysql.conf: |
MYSQL_DATABASE wordpress
MYSQL_USER admin
MYSQL_PASSWORD "1234"
MYSQL_RANDOM_ROOT_PASSWORD "1"
---
apiVersion: v1
kind: Service
metadata:
labels:
app: mysql
name: mysql
namespace: ex2
spec:
ports:
- port: 3306
protocol: TCP
targetPort: 3306
selector:
app: mysql
type: ClusterIP
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: mysql
labels:
app: mysql
namespace: ex2
spec:
replicas: 1
selector:
matchLabels:
app: mysql
template:
metadata:
labels:
app: mysql
spec:
containers:
- image: mysql:5.6
name: mysql
volumeMounts:
- name: config
mountPath: "/etc/env"
readOnly: true
ports:
- containerPort: 3306
protocol: TCP
volumes:
- name: config
configMap:
name: wordpress-mysql
---
apiVersion: v1
kind: Service
metadata:
labels:
app: wordpress
name: wordpress
namespace: ex2
spec:
ports:
- nodePort: 30999
port: 80
protocol: TCP
targetPort: 80
selector:
app: wordpress
type: NodePort
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: wordpress
labels:
app: wordpress
namespace: ex2
spec:
replicas: 1
selector:
matchLabels:
app: wordpress
template:
metadata:
labels:
app: wordpress
spec:
containers:
- image: wordpress
name: wordpress
volumeMounts:
- name: config
mountPath: "/etc/env"
readOnly: true
ports:
- containerPort: 80
protocol: TCP
volumes:
- name: config
configMap:
name: wordpress-mysql
When I deploy the app the mysql pod fails with this error:
kubectl -n ex2 logs mysql-56ddd69598-ql229
2020-12-26 19:57:58+00:00 [ERROR] [Entrypoint]: Database is
uninitialized and password option is not specified
You need to specify one of MYSQL_ROOT_PASSWORD, MYSQL_ALLOW_EMPTY_PASSWORD and MYSQL_RANDOM_ROOT_PASSWORD
I don't understand because I have specified everything in my configMap. I also have tried by using envFrom and Single Env Variables and it works just fine. I'm just having an issue with File in a Volume

Answer 1

#DavidMaze is correct; you're mixing two useful features.
Using test.yaml:
---
apiVersion: v1
kind: ConfigMap
metadata:
name: wordpress-mysql
data:
wordpress.conf: |
WORDPRESS_DB_HOST mysql
WORDPRESS_DB_USER admin
WORDPRESS_DB_PASSWORD "1234"
WORDPRESS_DB_NAME wordpress
WORDPRESS_DB_PREFIX wp_
mysql.conf: |
MYSQL_DATABASE wordpress
MYSQL_USER admin
MYSQL_PASSWORD "1234"
MYSQL_RANDOM_ROOT_PASSWORD "1"
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: test
labels:
app: test
spec:
replicas: 1
selector:
matchLabels:
app: test
template:
metadata:
labels:
app: test
spec:
containers:
- image: busybox
name: test
args:
- ash
- -c
- while true; do sleep 15s; done
volumeMounts:
- name: config
mountPath: "/etc/env"
readOnly: true
volumes:
- name: config
configMap:
name: wordpress-mysql
Then:
kubectl apply --filename=./test.yaml
kubectl exec --stdin --tty deployment/test -- ls /etc/env
mysql.conf wordpress.conf
kubectl exec --stdin --tty deployment/test -- more /etc/env/mysql.conf
MYSQL_DATABASE wordpress
MYSQL_USER admin
MYSQL_PASSWORD "1234"
MYSQL_RANDOM_ROOT_PASSWORD "1"
NOTE the files are missing (and should probably include) = between the variable and its value e.g. MYSQL_DATABASE=wordpress
So, what you have is a ConfigMap that represents 2 files (mysql.conf and wordpress.conf) and, if you use e.g. busybox and mount the ConfigMap as a volume, you can see that it includes 2 files and that the files contain the configurations.
So, if you can run e.g. WordPress or MySQL and pass a configuration file to them, you're good but what you probably want to do is reference the ConfigMap entries as environment variables, per #DavidMaze suggestion, i.e. run Pods with environment variables set by the ConfigMap entries, i.e.:
https://kubernetes.io/docs/tasks/configure-pod-container/configure-pod-configmap/#define-container-environment-variables-using-configmap-data

Answer 2

I would really suggest not to use configmap for wordpress. You can use directly the official repo https://github.com/docker-library/wordpress/tree/master/php7.4/apache it has a docker-entrypoint.sh which you can use to inject the env values from the deployment.yaml directly or if you use vault that works perfectly too.