How to merge two configmaps using volume mount in kubernetes
You have to use special projected volumes for achieve that. Example your deployment:
apiVersion: apps/v1
kind: Deployment
metadata:
name: testing
spec:
replicas: 1
selector:
matchLabels:
app: testing
template:
metadata:
name: testing
labels:
app: testing
spec:
containers:
- name: testing-container
image: testing
imagePullPolicy: IfNotPresent
ports:
- containerPort: __PORT__
volumeMounts:
- name: commonconfig-volume
mountPath: /usr/src/app/config
volumes:
- name: commonconfig-volume
projected:
sources:
- configMap:
name: test-configmap
- configMap:
name: common-config
You can use secret
same as configMap
You cannot mount two ConfigMaps to the same location.
But mentioning subPath
and key
for every item in each configmaps will let you get items from both configmaps in the same location. You'll have to write mount points for each file manually:
apiVersion: v1
kind: Pod
metadata:
name: config-single-file-volume-pod
spec:
containers:
- name: test-container
image: gcr.io/google_containers/busybox
command: [ "/bin/sh", "-c", "cat /etc/special-key" ]
volumeMounts:
- name: config-volume-1
mountPath: /etc/special-key1
subPath: path/to/special-key1
- name: config-volume-2
mountPath: /etc/special-key2
subPath: path/to/special-key2
volumes:
- name: config-volume-1
configMap:
name: test-configmap1
items:
- key: data-1
path: path/to/special-key1
- name: config-volume-2
configMap:
name: test-configmap2
items:
- key: data-2
path: path/to/special-key2
restartPolicy: Never
Another way is to mount them under same directory, but different subPath so that you don't have to specify items by hand. But, here keys from each configmap will be put into two different directories:
apiVersion: v1
kind: Pod
metadata:
name: config-single-file-volume-pod
spec:
containers:
- name: test-container
image: gcr.io/google_containers/busybox
command: [ "/bin/sh", "-c", "cat /etc/special-key" ]
volumeMounts:
- name: config-volume-1
mountPath: /etc/special-keys
subPath: cm1
- name: config-volume-2
mountPath: /etc/special-keys
subPath: cm2
volumes:
- name: config-volume-1
configMap:
name: test-configmap1
- name: config-volume-2
configMap:
name: test-configmap2
restartPolicy: Never
cm1
and cm2
will be two directories containing files derived from keys in test-configmap1
and test-configmap2
respectively.
Another example of how this can be done for mounting multiple configmaps. This for an nginx dock were you want to both replace the main /etc/nginx/nginx.conf and the files in /etc/nginx/conn.f. This also deletes the default.conf file in conf.d
containers:
- name: nginx-proxy
image: nginx:1.16-alpine
imagePullPolicy: Always
ports:
- containerPort: 443
- containerPort: 80
volumeMounts:
- name: nginx-main-conf-file
mountPath: /etc/nginx/nginx.conf
subPath: nginx.conf
- name: nginx-site-conf-file
mountPath: /etc/nginx/conf.d
volumes:
- name: nginx-main-conf-file
configMap:
name: nginx-main-conf
- name: nginx-site-conf-file
configMap:
name: nginx-site-conf
And one very important point. If you have any out commented lines (# something) in your yaml file, then this will not work. It's a bug. Tested in kubectl v1.14