How do pods in Google Container Engine talk/link to each other - docker

Question

I fiddle around with this example: https://cloud.google.com/container-engine/docs/tutorials/persistent-disk/
My modifications:
- I'm using my own Wordpress image [x] Works
Service starts (it needed more CPU 0.8 instead of 0.5, but now it works)
I want to use mariadb instead of mysql [ ] Fails!
I can't figure out how two pods link together!!!! ~5h + still failing
Here are my .yaml-Files
apiVersion: v1
kind: Pod
metadata:
name: wpsite
labels:
name: wpsite
spec:
containers:
- image: <my image on gcr.io>
name: wpsite
env:
- name: WORDPRESS_DB_PASSWORD
# Change this - must match mysql.yaml password.
value: example
ports:
- containerPort: 80
name: wpsite
volumeMounts:
# Name must match the volume name below.
- name: wpsite-disk
# Mount path within the container.
mountPath: /var/www/html
volumes:
- name: wpsite-disk
gcePersistentDisk:
# This GCE persistent disk must already exist.
pdName: wpsite-disk
fsType: ext4
service:
apiVersion: v1
kind: Service
metadata:
labels:
name: wpsite
name: wpsite
spec:
type: LoadBalancer
ports:
# The port that this service should serve on.
- port: 80
targetPort: 80
protocol: TCP
# Label keys and values that must match in order to receive traffic for this service.
selector:
name: wpsite
mariadb:
apiVersion: v1
kind: Pod
metadata:
name: mariadb
labels:
name: mariadb
spec:
containers:
- resources:
limits:
# 0.5 hat nicht funktioniert
# Fehlermeldung in: kubectl describe pod mariadb
cpu: 0.8
image: mariadb:10.1
name: mariadb
env:
- name: MYSQL_ROOT_PASSWORD
# Change this password!
value: example
ports:
- containerPort: 3306
name: mariadb
volumeMounts:
# This name must match the volumes.name below.
- name: mariadb-persistent-storage
mountPath: /var/lib/mysql
volumes:
- name: mariadb-persistent-storage
gcePersistentDisk:
# This disk must already exist.
pdName: mariadb-disk
fsType: ext4
maria-db-service:
apiVersion: v1
kind: Service
metadata:
labels:
name: mariadb
name: mariadb
spec:
ports:
# The port that this service should serve on.
- port: 3306
# Label keys and values that must match in
# order to receive traffic for this service.
selector:
name: mysql
kubectl logs wpsite shows error messages like this: Warning: mysqli::mysqli(): php_network_getaddresses: getaddrinfo failed: Name or service not known in - on line 10

Answer 1

OK - found it out!
It's the name in mariadb-service.yaml
metadata.name must be mysql and not mariadb, the selector in mariadb-service must point to mariadb (the pod)
Here are the working files:
mariadb.yaml
apiVersion: v1
kind: Pod
metadata:
name: mariadb
labels:
name: mariadb
spec:
containers:
- resources:
limits:
# 0.5 hat nicht funktioniert
# Fehlermeldung in: kubectl describe pod mariadb
cpu: 0.8
image: mariadb:10.1
name: mariadb
env:
- name: MYSQL_ROOT_PASSWORD
# Change this password!
value: example
ports:
- containerPort: 3306
name: mariadb
volumeMounts:
# This name must match the volumes.name below.
- name: mariadb-persistent-storage
mountPath: /var/lib/mysql
volumes:
- name: mariadb-persistent-storage
gcePersistentDisk:
# This disk must already exist.
pdName: mariadb-disk
fsType: ext4
mariadb-service.yaml
apiVersion: v1
kind: Service
metadata:
name: mysql
labels:
name: mysql
spec:
ports:
# The port that this service should serve on.
- port: 3306
# Label keys and values that must match in
# order to receive traffic for this service.
selector:
name: mariadb
wpsite.yaml
apiVersion: v1
kind: Pod
metadata:
name: wpsite
labels:
name: wpsite
spec:
containers:
- image: <change this to your imagename on gcr.io>
name: wpsite
env:
- name: WORDPRESS_DB_PASSWORD
# Change this - must match mysql.yaml password.
value: example
ports:
- containerPort: 80
name: wpsite
volumeMounts:
# Name must match the volume name below.
- name: wpsite-disk
# Mount path within the container.
mountPath: /var/www/html
volumes:
- name: wpsite-disk
gcePersistentDisk:
# This GCE persistent disk must already exist.
pdName: wpsite-disk
fsType: ext4
wpsite-service.yaml
apiVersion: v1
kind: Service
metadata:
name: wpsite
labels:
name: wpsite
spec:
type: LoadBalancer
ports:
# The port that this service should serve on.
- port: 80
targetPort: 80
protocol: TCP
# Label keys and values that must match in order to receive traffic for this service.
selector:
name: wpsite
With these settings I run: (my yaml-files are under gke)
$ kubectl create -f gke/mariadb.yaml
# Check
$ kubectl get pod
$ kubectl create -f gke/mariadb-service.yaml
# Check
$ kubectl get service mysql!!!! (name in mariadb = mysql)
$ kubectl create -f gke/wpsite.yaml
# Check
$ kubectl get pod
$ kubectl create -f gke/wpsite-service.yaml
# Check
$ kubectl describe service wpsite
Hope this helps someone...