I have noticed that when I create and mount a config map that contains some text files, the container will see those files as symlinks to ../data/myfile.txt .
For example, if my config map is named tc-configs and contains 2 xml files named stripe1.xml and stripe2.xml, if I mount this config map to /configs in my container, I will have, in my container :
bash-4.4# ls -al /configs/
total 12
drwxrwxrwx 3 root root 4096 Jun 4 14:47 .
drwxr-xr-x 1 root root 4096 Jun 4 14:47 ..
drwxr-xr-x 2 root root 4096 Jun 4 14:47 ..2018_06_04_14_47_03.291041453
lrwxrwxrwx 1 root root 31 Jun 4 14:47 ..data -> ..2018_06_04_14_47_03.291041453
lrwxrwxrwx 1 root root 18 Jun 4 14:47 stripe1.xml -> ..data/stripe1.xml
lrwxrwxrwx 1 root root 18 Jun 4 14:47 stripe2.xml -> ..data/stripe2.xmlI guess Kubernetes requires those symlinks and ../data and ..timestamp/ folders, but I know some applications that can fail to startup if they see non expected files or folders
Is there a way to tell Kubernetes not to generate all those symlinks and directly mount the files ?
I am afraid I don't know if you can tell Kubernetes not to generate those symlinks although I think that it is a native behaviour.
If having those files and links is an issue, a workaround that I can think of is to mount the configmap on one folder and copy the files over to another folder when you initialise the container:
initContainers:
- name: copy-config
image: busybox
command: ['sh', '-c', 'cp /configmap/* /configs']
volumeMounts:
- name: configmap
mountPath: /configmap
- name: config
mountPath: /configsBut you would have to declare two volumes, one for the configMap (configmap) and one for the final directory (config):
volumes:
- name: config
emptyDir: {}
- name: configmap
configMap:
name: myconfigmap
Change the type of volume for the config volume as you please obviously.
I think this solution is satisfactory : specifying exact file path in mountPath, will get rid of the symlinks to ..data and ..2018_06_04_19_31_41.860238952
So if I apply such a manifest :
apiVersion: v1
kind: Pod
metadata:
name: my-lamp-site
spec:
containers:
- name: php
image: php:7.0-apache
volumeMounts:
- mountPath: /var/www/html/users.xml
name: site-data
subPath: users.xml
volumes:
- name: site-data
configMap:
name: users
---
apiVersion: v1
kind: ConfigMap
metadata:
name: users
data:
users.xml: |
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<users>
</users>
Apparently, I'm making use of subpath explicitly, and they're not part of the "auto update magic" from ConfigMaps, I won't see any more symlinks :
$ kubectl exec my-lamp-site -c php -- ls -al /var/www/html
total 12
drwxr-xr-x 1 www-data www-data 4096 Jun 4 19:18 .
drwxr-xr-x 1 root root 4096 Jun 4 17:58 ..
-rw-r--r-- 1 root root 73 Jun 4 19:18 users.xmlBe careful to not forget subPath, otherwise users.xml will be a directory !
Back to my initial manifest :
spec:
containers:
- name: php
image: php:7.0-apache
volumeMounts:
- mountPath: /var/www/html
name: site-data
volumes:
- name: site-data
configMap:
name: usersI'll see those symlinks coming back :
$ kubectl exec my-lamp-site -c php -- ls -al /var/www/html
total 12
drwxrwxrwx 3 root root 4096 Jun 4 19:31 .
drwxr-xr-x 3 root root 4096 Jun 4 17:58 ..
drwxr-xr-x 2 root root 4096 Jun 4 19:31 ..2018_06_04_19_31_41.860238952
lrwxrwxrwx 1 root root 31 Jun 4 19:31 ..data -> ..2018_06_04_19_31_41.860238952
lrwxrwxrwx 1 root root 16 Jun 4 19:31 users.xml -> ..data/users.xmlMany thanks to psycotica0 on K8s Canada slack for putting me on the right track with subpath (they are quickly mentioned in configmap documentation)