Why can't I access a ClusterIP service thru its name? - docker

Question

I set up a simple redis ClusterIP service to be accessed by a php LoadBalancer service inside the Cluster. The php log shows the connection timeout error. The redis service is not accessible.
'production'.ERROR: Operation timed out {"exception":"[object] (RedisException(code: 0):
Operation timed out at /var/www/html/vendor/laravel/framework/src/Illuminate/Redis
/html/vendor/laravel/framework/src/Illuminate/Redis/Connectors/PhpRedisConnector.php(109):
Redis->connect('redis-svc', '6379', 0, '', 0, 0)
My redis service is quite simple so I don't know what went wrong:
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
labels:
io.kompose.service: redis
name: redis
spec:
replicas: 1
strategy: {}
template:
metadata:
labels:
io.kompose.service: redis
spec:
containers:
- image: redis:alpine
name: redis
resources: {}
ports:
- containerPort: 6379
restartPolicy: Always
status: {}
---
kind: Service
apiVersion: v1
metadata:
name: redis-svc
spec:
selector:
app: redis
ports:
- protocol: TCP
port: 6379
targetPort: 6379
type: ClusterIP
I verify redis-svc is running, so why it can't be access by other service
kubectl get service redis-svc git:k8s*
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
redis-svc ClusterIP 10.101.164.225 <none> 6379/TCP 22m
This SO kubernetes cannot ping another service said ping doesn't work with service's cluster IP(indeed) how do I verify whether redis-svc can be accessed or not ?
---- update ----
My first question was a silly mistake but I still don't know how do I verify whether the service can be accessed or not (by its name). For example I changed the service name to be the same as the deployment name and I found php failed to access redis again.
kubectl get endpoints did not help now.
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: redis
...
status: {}
---
kind: Service
apiVersion: v1
metadata:
name: redis
...
my php is another service with env set the redis's service name
spec:
containers:
- env:
- name: REDIS_HOST # the php code access this variable
value: redis-svc #changed to "redis" when redis service name changed to "redis"
----- update 2------
The reason I can' set my redis service name to "redis" is b/c "kubelet adds a set of environment variables for each active Service" so with the name "redis", there will be a REDIS_PORT=tcp://10.101.210.23:6379 which overwrite my own REDIS_PORT=6379
But my php just expect the value of REDIS_PORT to be 6379

Answer 1

I ran the yaml configuration given by you and it created the deployment and service. However when I run the below commands:
>>> kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 5d14h
redis-svc ClusterIP 10.105.31.201 <none> 6379/TCP 109s
>>>> kubectl get endpoints
NAME ENDPOINTS AGE
kubernetes 192.168.99.116:8443 5d14h
redis-svc <none> 78s
As you see, the endpoints for redis-svc is none, it means that the service doesn't have an endpoint to connect to. You are using selector labels as app: redis in the redis-svc. But the pods doesn't have the selector label defined in the service. Adding the label app: redis to the pod template will work. The complete working yaml configuration of deployment will look like:
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
labels:
io.kompose.service: redis
name: redis
spec:
replicas: 1
strategy: {}
template:
metadata:
labels:
io.kompose.service: redis
app: redis
spec:
containers:
- image: redis:alpine
name: redis
resources: {}
ports:
- containerPort: 6379
restartPolicy: Always
status: {}