This Kubernetes project is implementing the wordpress application that shares an NFS volume with mySQL. The idea behind sharing a NFS volume between pods is to implement in the next step a StatefulSet for mySQL. This StatefulSet application will need to share the database between all the pods of mySQL so that a multi node database is created that ensures the requested high performance.
To do that, there is an example janakiramm/wp-statefulset. This example is using etcd. So why not using nfs in stead of etcd?
Below is then a trial to implement it with nfs.
gcloud compute disks create --size=5GB --zone=us-east1-b gce-nfs-disk
gcloud container clusters create mappedinn-cluster --num-nodes=3
# (if needed)
gcloud container clusters get-credentials mappedinn-cluster --zone us-east1-b --project mappedinn
# creation of PV and PVC for the nfs server Deployment
kubectl create -f 01-pv-gce.yml
# creation of the Deployment for the NFS server
kubectl create -f 02-dep-nfs.yml
# Creation of a service for the NFS server
kubectl create -f 03-srv-nfs.yml
# Getting the IP address of the `nfs-server` to update the file 04-pv-pvc.yml file
kubectl get services
# Creation of the NFS PV and NFS PVC to be shared by wordpress and mysql
kubectl create -f 04-pv-pvc.yml
# create a mysql Deployment with its service
kubectl create -f 05-mysql.yml
# create a wordpress Deployment with its service
kubectl create -f 06-wordpress.yml
The problem is that the wordpress pod is not succeding to start as it can be seen down:
$ kubectl get pods
NAME READY STATUS RESTARTS AGE
nfs-server-2899972627-jgjx0 1/1 Running 0 4m
wp01-mysql-1941769936-m9jjd 1/1 Running 0 3m
wp01-wordpress-2362719074-bv53t 0/1 CrashLoopBackOff 4 2m
This is the output of the kubectl describe pods:
$ kubectl describe pods wp01-wordpress-2362719074-bv53t
Name: wp01-wordpress-2362719074-bv53t
Namespace: default
Node: gke-mappedinn-cluster-default-pool-6264f94a-z0sh/10.240.0.4
Start Time: Thu, 04 May 2017 05:59:12 +0400
Labels: app=wp01
pod-template-hash=2362719074
tier=frontend
Annotations: kubernetes.io/created-by={"kind":"SerializedReference","apiVersion":"v1","reference":{"kind":"ReplicaSet","namespace":"default","name":"wp01-wordpress-2362719074","uid":"44b91da0-306d-11e7-a0d1-42010a...
kubernetes.io/limit-ranger=LimitRanger plugin set: cpu request for container wordpress
Status: Running
IP: 10.244.0.4
Controllers: ReplicaSet/wp01-wordpress-2362719074
Containers:
wordpress:
Container ID: docker://658c7392c1b7a5033fe1a1b456a9653161003ee2878a4f02c6a12abb49241d47
Image: wordpress:4.6.1-apache
Image ID: docker://sha256:ee397259d4e59c65e2c1c5979a3634eb3ab106bba389acea8b21862053359134
Port: 80/TCP
State: Waiting
Reason: CrashLoopBackOff
Last State: Terminated
Reason: Error
Exit Code: 1
Started: Thu, 04 May 2017 06:03:16 +0400
Finished: Thu, 04 May 2017 06:03:16 +0400
Ready: False
Restart Count: 5
Requests:
cpu: 100m
Environment:
WORDPRESS_DB_HOST: wp01-mysql
WORDPRESS_DB_PASSWORD: <set to the key 'password' in secret 'wp01-pwd-wordpress'> Optional: false
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-k650h (ro)
/var/www/html from wordpress-persistent-storage (rw)
Conditions:
Type Status
Initialized True
Ready False
PodScheduled True
Volumes:
wordpress-persistent-storage:
Type: PersistentVolumeClaim (a reference to a PersistentVolumeClaim in the same namespace)
ClaimName: wp01-pvc-data
ReadOnly: false
default-token-k650h:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-k650h
Optional: false
QoS Class: Burstable
Node-Selectors: <none>
Tolerations: <none>
Events:
FirstSeen LastSeen Count From SubObjectPath Type Reason Message
--------- -------- ----- ---- ------------- -------- ------ -------
5m 5m 1 default-scheduler Normal Scheduled Successfully assigned wp01-wordpress-2362719074-bv53t to gke-mappedinn-cluster-default-pool-6264f94a-z0sh
4m 4m 1 kubelet, gke-mappedinn-cluster-default-pool-6264f94a-z0sh spec.containers{wordpress} Normal Pulling pulling image "wordpress:4.6.1-apache"
4m 4m 1 kubelet, gke-mappedinn-cluster-default-pool-6264f94a-z0sh spec.containers{wordpress} Normal Pulled Successfully pulled image "wordpress:4.6.1-apache"
4m 4m 1 kubelet, gke-mappedinn-cluster-default-pool-6264f94a-z0sh spec.containers{wordpress} Normal Created Created container with docker id 8647e997d6f4; Security:[seccomp=unconfined]
4m 4m 1 kubelet, gke-mappedinn-cluster-default-pool-6264f94a-z0sh spec.containers{wordpress} Normal Started Started container with docker id 8647e997d6f4
4m 4m 1 kubelet, gke-mappedinn-cluster-default-pool-6264f94a-z0sh spec.containers{wordpress} Normal Created Created container with docker id 37f4f0fd392d; Security:[seccomp=unconfined]
4m 4m 1 kubelet, gke-mappedinn-cluster-default-pool-6264f94a-z0sh spec.containers{wordpress} Normal Started Started container with docker id 37f4f0fd392d
4m 4m 1 kubelet, gke-mappedinn-cluster-default-pool-6264f94a-z0sh Warning FailedSync Error syncing pod, skipping: failed to "StartContainer" for "wordpress" with CrashLoopBackOff: "Back-off 10s restarting failed container=wordpress pod=wp01-wordpress-2362719074-bv53t_default(44ba1226-306d-11e7-a0d1-42010a8e0084)"
3m 3m 1 kubelet, gke-mappedinn-cluster-default-pool-6264f94a-z0sh spec.containers{wordpress} Normal Created Created container with docker id b78a661388a2; Security:[seccomp=unconfined]
3m 3m 1 kubelet, gke-mappedinn-cluster-default-pool-6264f94a-z0sh spec.containers{wordpress} Normal Started Started container with docker id b78a661388a2
3m 3m 2 kubelet, gke-mappedinn-cluster-default-pool-6264f94a-z0sh Warning FailedSync Error syncing pod, skipping: failed to "StartContainer" for "wordpress" with CrashLoopBackOff: "Back-off 20s restarting failed container=wordpress pod=wp01-wordpress-2362719074-bv53t_default(44ba1226-306d-11e7-a0d1-42010a8e0084)"
3m 3m 1 kubelet, gke-mappedinn-cluster-default-pool-6264f94a-z0sh spec.containers{wordpress} Normal Created Created container with docker id 2b6384407678; Security:[seccomp=unconfined]
3m 3m 1 kubelet, gke-mappedinn-cluster-default-pool-6264f94a-z0sh spec.containers{wordpress} Normal Started Started container with docker id 2b6384407678
3m 2m 4 kubelet, gke-mappedinn-cluster-default-pool-6264f94a-z0sh Warning FailedSync Error syncing pod, skipping: failed to "StartContainer" for "wordpress" with CrashLoopBackOff: "Back-off 40s restarting failed container=wordpress pod=wp01-wordpress-2362719074-bv53t_default(44ba1226-306d-11e7-a0d1-42010a8e0084)"
2m 2m 1 kubelet, gke-mappedinn-cluster-default-pool-6264f94a-z0sh spec.containers{wordpress} Normal Created Created container with docker id 930a3410b213; Security:[seccomp=unconfined]
2m 2m 1 kubelet, gke-mappedinn-cluster-default-pool-6264f94a-z0sh spec.containers{wordpress} Normal Started Started container with docker id 930a3410b213
2m 1m 7 kubelet, gke-mappedinn-cluster-default-pool-6264f94a-z0sh Warning FailedSync Error syncing pod, skipping: failed to "StartContainer" for "wordpress" with CrashLoopBackOff: "Back-off 1m20s restarting failed container=wordpress pod=wp01-wordpress-2362719074-bv53t_default(44ba1226-306d-11e7-a0d1-42010a8e0084)"
4m 1m 5 kubelet, gke-mappedinn-cluster-default-pool-6264f94a-z0sh spec.containers{wordpress} Normal Pulled Container image "wordpress:4.6.1-apache" already present on machine
1m 1m 1 kubelet, gke-mappedinn-cluster-default-pool-6264f94a-z0sh spec.containers{wordpress} Normal Created Created container with docker id 658c7392c1b7; Security:[seccomp=unconfined]
1m 1m 1 kubelet, gke-mappedinn-cluster-default-pool-6264f94a-z0sh spec.containers{wordpress} Normal Started Started container with docker id 658c7392c1b7
4m 10s 19 kubelet, gke-mappedinn-cluster-default-pool-6264f94a-z0sh spec.containers{wordpress} Warning BackOff Back-off restarting failed docker container
1m 10s 5 kubelet, gke-mappedinn-cluster-default-pool-6264f94a-z0sh Warning FailedSync Error syncing pod, skipping: failed to "StartContainer" for "wordpress" with CrashLoopBackOff: "Back-off 2m40s restarting failed container=wordpress pod=wp01-wordpress-2362719074-bv53t_default(44ba1226-306d-11e7-a0d1-42010a8e0084)"
# deleting the cluser
gcloud container clusters delete mappedinn-cluster
# deleting the GCE PV
gcloud compute disks delete gce-nfs-disk