How to mount volume with specific UID in Kubernetes Pod?
Solution 1:
There is no way to set the UID
using the definition of Pod
, but Kubernetes saves the UID
of sourced volume.
So, you can set the UID
by InitContainer
, which launches before the main container, just add it to the containers
path of the Deployment
:
initContainers:
- name: volume-mount-hack
image: busybox
command: ["sh", "-c", "chown -R 200:200 /nexus"]
volumeMounts:
- name: <your nexus volume>
mountPath: /nexus
Solution 2:
Like Anton said, although we can't set the UID using the definition of Pod. Here comes another workaround for this topic.
Please refer to the Kubernetes official document Configure a Security Context for a Pod or Container
The pod definition I used:
apiVersion: v1
kind: Pod
metadata:
name: nexus3
labels:
app: nexus3
spec:
securityContext:
fsGroup: 200
volumes:
- name: nexus-data-vol
emptyDir: {}
containers:
- name: nexus3-container
image: sonatype/nexus3
volumeMounts:
- name: nexus-data-vol
mountPath: /nexus-data
The Service definition:
apiVersion: v1
kind: Service
metadata:
name: nexus3-service
spec:
type: NodePort
ports:
- port: 8081
nodePort: 30390
protocol: TCP
targetPort: 8081
selector:
app: nexus3
And then create pod and service without any permission denied or other errors:
# kubectl create -f nexus3.yaml
# kubectl create -f nexus3-svc.yaml
Try to login the Nexus3 container and check the owner/permission of /nexus-data:
# kubectl exec -it nexus3 -- sh
sh-4.2$ ls -ld /nexus-data/
drwxrwsrwx 16 root nexus 4096 Mar 13 09:00 /nexus-data/
sh-4.2$
As you can see, the directory belongs to root:nexus, and you can also check the files in the directory:
sh-4.2$ cd /nexus-data/
sh-4.2$ ls -l
total 72
drwxr-sr-x 3 nexus nexus 4096 Mar 13 09:00 blobs
drwxr-sr-x 269 nexus nexus 12288 Mar 13 08:59 cache
drwxr-sr-x 8 nexus nexus 4096 Mar 13 09:00 db
drwxr-sr-x 3 nexus nexus 4096 Mar 13 09:00 elasticsearch
drwxr-sr-x 3 nexus nexus 4096 Mar 13 08:59 etc
drwxr-sr-x 2 nexus nexus 4096 Mar 13 08:59 generated-bundles
drwxr-sr-x 2 nexus nexus 4096 Mar 13 08:59 instances
drwxr-sr-x 3 nexus nexus 4096 Mar 13 08:59 javaprefs
drwxr-sr-x 2 nexus nexus 4096 Mar 13 08:59 kar
drwxr-sr-x 3 nexus nexus 4096 Mar 13 08:59 keystores
-rw-r--r-- 1 nexus nexus 8 Mar 13 08:59 lock
drwxr-sr-x 2 nexus nexus 4096 Mar 13 09:00 log
drwxr-sr-x 2 nexus nexus 4096 Mar 13 08:59 orient
-rw-r--r-- 1 nexus nexus 5 Mar 13 08:59 port
drwxr-sr-x 2 nexus nexus 4096 Mar 13 08:59 restore-from-backup
drwxr-sr-x 7 nexus nexus 4096 Mar 13 09:00 tmp
sh-4.2$ touch test-file
sh-4.2$ ls -l test-file
-rw-r--r-- 1 nexus nexus 0 Mar 13 09:13 test-file
sh-4.2$ mkdir test-dir
sh-4.2$ ls -l test-dir
total 0
sh-4.2$ ls -ld test-dir
drwxr-sr-x 2 nexus nexus 4096 Mar 13 09:13 test-dir
That is the power of SetGID :)
Now Let's check the service is working or not. I use minikube to running a kubernetes cluster:
chris@XPS-13-9350 ~ $ minikube service nexus3-service --url
http://192.168.39.95:30390
chris@XPS-13-9350 ~ $ curl -u admin:admin123 http://192.168.39.95:30390/service/metrics/ping
pong
The service is working as expected.