minikube shared volume not shows files after sometime - docker

Question

I have to share local .ssh directory content to pod. I search for hat and got answer from one of the post to share start as --mount-string.
$ minikube start --mount-string="$HOME/.ssh/:/ssh-directory" --mount
😄 minikube v1.9.2 on Darwin 10.14.6
✨ Using the docker driver based on existing profile
👍 Starting control plane node m01 in cluster minikube
🚜 Pulling base image ...
🔄 Restarting existing docker container for "minikube" ...
🐳 Preparing Kubernetes v1.18.0 on Docker 19.03.2 ...
▪ kubeadm.pod-network-cidr=10.244.0.0/16
E0426 23:44:18.447396 80170 kubeadm.go:331] Overriding stale ClientConfig host https://127.0.0.1:32810 with https://127.0.0.1:32813
📁 Creating mount /Users/myhome/.ssh/:/ssh-directory ...
🌟 Enabling addons: default-storageclass, storage-provisioner
🏄 Done! kubectl is now configured to use "minikube"
❗ /usr/local/bin/kubectl is v1.15.5, which may be incompatible with Kubernetes v1.18.0.
💡 You can also use 'minikube kubectl -- get pods' to invoke a matching version
When I check the docker for the given Minikube, it return
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
5ad64f642b63 gcr.io/k8s-minikube/kicbase:v0.0.8 "/usr/local/bin/entr…" 3 weeks ago Up 45 seconds 127.0.0.1:32815->22/tcp, 127.0.0.1:32814->2376/tcp, 127.0.0.1:32813->8443/tcp minikube
And check the .ssh directory content are there or not.
$ docker exec -it 5ad64f642b63 ls /ssh-directory
id_rsa id_rsa.pub known_hosts
I have deployment yml as
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: api-deployment
labels:
stack: api
app: api-web
spec:
replicas: 1
selector:
matchLabels:
app: api-web
template:
metadata:
labels:
app: api-web
spec:
containers:
- name: api-web-pod
image: tiangolo/uwsgi-nginx-flask
ports:
- name: api-web-port
containerPort: 80
envFrom:
- secretRef:
name: api-secrets
volumeMounts:
- name: ssh-directory
mountPath: /app/.ssh
volumes:
- name: ssh-directory
hostPath:
path: /ssh-directory/
type: Directory
When it ran, it gives error for /ssh-directory.
$ kubectl describe pod/api-deployment-f65db9c6c-cwtvt
Name: api-deployment-f65db9c6c-cwtvt
Namespace: default
Priority: 0
Node: minikube/172.17.0.2
Start Time: Sat, 02 May 2020 23:07:51 -0500
Labels: app=api-web
pod-template-hash=f65db9c6c
Annotations: <none>
Status: Pending
IP:
Controlled By: ReplicaSet/api-deployment-f65db9c6c
Containers:
api-web-pod:
Container ID:
Image: tiangolo/uwsgi-nginx-flask
Image ID:
Port: 80/TCP
Host Port: 0/TCP
State: Waiting
Reason: ContainerCreating
Ready: False
Restart Count: 0
Environment Variables from:
api-secrets Secret Optional: false
Environment: <none>
Mounts:
/app/.ssh from ssh-directory (rw)
/var/run/secrets/kubernetes.io/serviceaccount from default-token-9shz5 (ro)
Conditions:
Type Status
Initialized True
Ready False
ContainersReady False
PodScheduled True
Volumes:
ssh-directory:
Type: HostPath (bare host directory volume)
Path: /ssh-directory/
HostPathType: Directory
default-token-9shz5:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-9shz5
Optional: false
QoS Class: BestEffort
Node-Selectors: <none>
Tolerations: node.kubernetes.io/not-ready:NoExecute for 300s
node.kubernetes.io/unreachable:NoExecute for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled <unknown> default-scheduler Successfully assigned default/api-deployment-f65db9c6c-cwtvt to minikube
Warning FailedMount 11m kubelet, minikube Unable to attach or mount volumes: unmounted volumes=[ssh-directory], unattached volumes=[default-token-9shz5 ssh-directory]: timed out waiting for the condition
Warning FailedMount 2m13s (x4 over 9m) kubelet, minikube Unable to attach or mount volumes: unmounted volumes=[ssh-directory], unattached volumes=[ssh-directory default-token-9shz5]: timed out waiting for the condition
Warning FailedMount 62s (x14 over 13m) kubelet, minikube MountVolume.SetUp failed for volume "ssh-directory" : hostPath type check failed: /ssh-directory/ is not a directory
When I check the content of /ssh-directory in docker.
It gives IO error.
$ docker exec -it 5ad64f642b63 ls /ssh-directory
ls: cannot access '/ssh-directory': Input/output error
I know there are default mount points for Minikube. As mentioned in https://minikube.sigs.k8s.io/docs/handbook/mount/,
+------------+----------+---------------+----------------+
| Driver | OS | HostFolder | VM |
+------------+----------+---------------+----------------+
| VirtualBox | Linux | /home |/hosthome |
+------------+----------+---------------+----------------+
| VirtualBox | macOS | /Users |/Users |
+------------+----------+---------------+----------------+
| VirtualBox | Windows |C://Users | /c/Users |
+------------+----------+---------------+----------------+
|VMware Fusio| macOS |/Users |/Users |
+------------+----------+---------------+----------------+
| KVM | Linux | Unsupported. | |
+------------+----------+---------------+----------------+
| HyperKit | Linux | Unsupported |(see NFS mounts)|
+------------+----------+---------------+----------------+
But I installed minikube as brew install minikube and its set driver as docker.
$ cat ~/.minikube/config/config.json
{
"driver": "docker"
}
There is no mapping for docker driver in mount point.
Initially, this directory has the files, but somehow, when I try to create the pod, it delete or something is wrong.

Answer 1

While reproducing this on ubuntu I encountered the exact issue.
The directory was indeed looked like mounted but the files were missing which lead me to think that this is a general issue with mounting directories with docker driver.
There is open issue on github about the same problem ( mount directory empty ) and open feature request to mount host volumes into docker driver.
Inspecting minikube container shows no record of that mounted volume and confirms information mentioned in the github request that the only volume shared with host as of now is the one that mounts by default (that is /var/lib/docker/volumes/minikube/_data mounted into minikube's /var directory).
$ docker inspect minikube
"Mounts": [
{
"Type": "volume",
"Name": "minikube",
"Source": "/var/lib/docker/volumes/minikube/_data",
"Destination": "/var",
"Driver": "local",
"Mode": "z",
"RW": true,
"Propagation": ""
}
As the workaround you could copy your .ssh directory into the running minikube docker container with following command:
docker cp $HOME/.ssh minikube:<DESIRED_DIRECTORY>
and then mount this desired directory into the pod.