I have run a basic example project and can confirm it is running, but I cannot identify its URL?
Kubectl describe service - gives me
NAME READY STATUS RESTARTS AGE
frontend-6c8b5cc5b-v9jlb 1/1 Running 0 26s
PS D:\git\helm3\lab1_kubectl_version1\yaml> kubectl describe service
Name: frontend
Namespace: default
Labels: name=frontend
Annotations: <none>
Selector: app=frontend
Type: ClusterIP
IP Family Policy: SingleStack
IP Families: IPv4
IP: 10.108.59.44
IPs: 10.108.59.44
Port: <unset> 80/TCP
TargetPort: 4200/TCP
Endpoints: 10.1.0.38:4200
Session Affinity: None
Events: <none>
Name: kubernetes
Namespace: default
Labels: component=apiserver
provider=kubernetes
Annotations: <none>
Should I be able to hit this locally or not? The demo suggests yes but no URL is given and anything I attempt fails.
From outside you do not have any way to connect to your service since its type is set to ClusterIP if you want directly to expose your service, you should set it to either type LoadBalancer or NodePort. For more info about these types check this link.
However your service has an internal url ( which works within the cluster, for example if you exec into a pod and curl that url, you will get a response ) and that is: <your service>.<your namespace>.svc.cluster.local
Instead of <your service> type the name of the service and instead of <your namespace> namespace in which that service resides. The rest of the url is the same for all services.
Related
I am following the instructions here:
https://z2jh.jupyter.org/en/stable/jupyterhub/installation.html
to install locally with kubernetes and minikube a jupyter hub.
Its almost done as can be seen in the pic
the namespace is called k8s-namespace-jose
I had to run the command:
kubectl --namespace get service proxy-public --output jsonpath='{.status.loadBalancer.ingress[].ip}'
In order to get the EXTERNAL-IP shown above.
The thing is that going to:
http://104.196.41.97 does not work (server not responding)
nor the folowing works:
http://104.196.41.97:80
the error that I get is:
What can I do in order to get my jupyterhub in my local server?
EDIT:
In order to have all the info about the loadbalancer:
Name: proxy-public
Namespace: k8s-namespace-jose
Labels: app=jupyterhub
app.kubernetes.io/managed-by=Helm
chart=jupyterhub-2.0.0
component=proxy-public
heritage=Helm
release=helm-release-name-jose
Annotations: meta.helm.sh/release-name: helm-release-name-jose
meta.helm.sh/release-namespace: k8s-namespace-jose
Selector: component=proxy,release=helm-release-name-jose
Type: LoadBalancer
IP Family Policy: SingleStack
IP Families: IPv4
IP: 10.103.131.233
IPs: 10.103.131.233
External IPs: 104.196.41.97
Port: http 80/TCP
TargetPort: http/TCP
NodePort: http 32297/TCP
Endpoints: 10.244.0.13:8000
Session Affinity: None
External Traffic Policy: Cluster
Events: <none>
Due to the minikube installation, probably the address is the address of minikube cluster and not the External-IP
Can you try an alternative to hit the minikube IP instead of the External IP?
sgrigori#sgrigori-vbox:~/Dev/jupyterhub$ minikube ip
192.168.49.2
and use your node port 32297
http://192.168.49.2:32297
In my namespace I have services
k get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
blue-service NodePort 10.107.127.118 <none> 80:32092/TCP 60m
demo ClusterIP 10.111.134.22 <none> 80/TCP 3d
I added blue-service to /etc/hosts
It failes again
wget -O- blue-service
--2022-06-13 11:11:32-- http://blue-service/
Resolving blue-service (blue-service)... 10.107.127.118
Connecting to blue-service (blue-service)|10.107.127.118|:80... failed: Connection timed out.
Retrying.
I decided to chech with describe
Name: blue-service
Namespace: default
Labels: app=blue
Annotations: <none>
Selector: app=blue
Type: NodePort
IP Family Policy: SingleStack
IP Families: IPv4
IP: 10.107.127.118
IPs: 10.107.127.118
Port: <unset> 80/TCP
TargetPort: 8080/TCP
NodePort: <unset> 32092/TCP
Endpoints: 172.17.0.39:8080,172.17.0.40:8080,172.17.0.41:8080
Session Affinity: None
External Traffic Policy: Cluster
Events: <none>
Why?
The services you are referring to do not have an external IP (the External IP field is empty) so you cannot access those services.
If you want to access those services, you either need to
Make them a LoadBalancer service type which will give them an external IP
or
Use kubectl port-forward to connect a local port on your machine to the service then use localhost:xxxx to access the service
If you want to map a DNS name to the service, you should look at the External DNS project as mentioned in this answer which will allow you to create DNS entries in your provider's DNS service (if you are running the cluster on a managed platform)
OR, use nip.io if you're only testing
Hi Kubernetes Experts,
I have an application cluster running in the azure kubernetes cluster. There are 3 pods inside the application cluster. The app is designed in a way, that each pod listens on a different port. For example, pod 1 listens on 31090, pod2 on 31091 and pod 3 on 31092.
This application is needed to be connected from outside the network. At this point, I need to create a separate load balancer service for each of the pods.
In the service, I cannot use selector as app name/label as it tries to distribute traffic between all 3 pods in round robin way. Now as you see above that one port (say 31090) is running only on one pod. So, external connections to the load balancer IP fails 2/3 rd of times.
So, I am trying to create 3 different load balancer services individual to each pod, without mentioning the selector and later assigning endpoint individually to them.
The approach is explained here:
In Kubernetes, how does one select a pod by name in a service selector?
But after the endpoint is created, the service shows endpoint as blank. See below.
First I created only the service
---
apiVersion: v1
kind: Service
metadata:
name: myservice
spec:
ports:
- protocol: TCP
port: 31090
targetPort: 31090
name: b0
type: LoadBalancer
After this, the service shows endpoint as "none". So far, so good.
kubectl describe service myservice
Name: myservice
Namespace: confluent
Labels: <none>
Annotations: <none>
Selector: <none>
Type: LoadBalancer
IP: 10.0.184.1
Port: b0 31090/TCP
TargetPort: 31090/TCP
NodePort: b0 31354/TCP
**Endpoints: <none>**
Session Affinity: None
External Traffic Policy: Cluster
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal EnsuringLoadBalancer 3s service-controller Ensuring load balancer
Then I create the end point, I have made sure the names match between service and endpoint, including any spaces or tabs. But the endpoint in service desc shows "" (blank). And this is why, I am unable to get to the app from outside network. Telnet to the port and external IP just keeps trying.
---
apiVersion: v1
kind: Endpoints
metadata:
name: myservice
subsets:
- addresses:
- ip: 10.240.1.32
ports:
- port: 31090
kubectl describe service myservice
Name: myservice
Namespace: confluent
Labels: <none>
Annotations: <none>
Selector: <none>
Type: LoadBalancer
IP: 10.0.184.1
LoadBalancer Ingress: 20.124.49.192
Port: b0 31090/TCP
TargetPort: 31090/TCP
NodePort: b0 31354/TCP
**Endpoints:**
Session Affinity: None
External Traffic Policy: Cluster
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal EnsuringLoadBalancer 3m22s service-controller Ensuring load balancer
Normal EnsuredLoadBalancer 3m10s service-controller Ensured load balancer
Only this service is failing (using no selector). All my other external load balancer services are working fine. They all are getting to the pods. They all are using selector as app label.
Here is the pod ip. I have ensured port 31090 is running inside the pod.
kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
ck21-cp-kafka-0 2/2 Running 2 (76m ago) 78m **10.240.1.32** aks-agentpool-26199219-vmss000013 <none> <none>
Can someone please help me here?
Thanks !
This is my first time running through the Kubernetes tutorial.
I installed Docker, Kubectl and Minikube on a headless Ubuntu server (18.04).
I ran Minikube like this -
minikube start --vm-driver=none
I have a local docker image that run a restful service on port 9110. I create a deployment and expose it like this -
kubectl run hello-node --image=dbtemplate --port=9110 --image-pull-policy=Never
kubectl expose deployment hello-node --type=NodePort
status of my service -
# kubectl get services
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
hello-node NodePort 10.98.104.45 <none> 9110:32651/TCP 39m
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 3h2m
# kubectl describe services hello-node
Name: hello-node
Namespace: default
Labels: run=hello-node
Annotations: <none>
Selector: run=hello-node
Type: NodePort
IP: 10.98.104.45
Port: <unset> 9110/TCP
TargetPort: 9110/TCP
NodePort: <unset> 32651/TCP
Endpoints: 172.17.0.5:9110
Session Affinity: None
External Traffic Policy: Cluster
Events: <none>
# minikube ip
192.168.1.216
As you can see, the service is available on the internal IP of 172.17.0.5.
Is there some way for me to get this service mapped to/exposed on the IP of the parent host, which is 192.168.1.216. I would like my restful service at 192.168.1.216:9110.
I think minikube tunnel might be what you're looking for. https://github.com/kubernetes/minikube/blob/master/docs/networking.md
Services of type LoadBalancer can be exposed via the minikube tunnel command.
Within the same kubernetes cluster,
Can I have multiple StatefulSets attached to one headless service or should each StatefulSet have it's own headless service? What are the pros and cons of doing this?
Can I mix standard and headless services in the same cluster? Specifically, I would like to use LoadBalancer service to load balance headless services. Can I define a service of type LoadBalancer and have headless services (ClusterIP = None) attached to it? If yes, how can I achieve this?
Here is my intended architecture:
Load Balancer Service
- Headless Service (Database-service)
- MySql
- BlazeGraph
- Headless Service (Web / Tomcat)
- Web Service (RESTful / GraphQL)
Any advice and insight is appreciated.
My setup
My service and the statefulsets attached to it have different labels.
database-service: app=database
mysqlset: app=mysql
My pods
khteh#khteh-T580:~ 2007 $ k get pods -l app=mysql -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE
mysql-0 1/1 Running 1 18h 10.1.1.4 khteh-t580 <none>
khteh#khteh-T580:~ 2008 $ k get pods -l app=blazegraph -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE
blazegraph-0 1/1 Running 1 18h 10.1.1.254 khteh-t580 <none>
khteh#khteh-T580:~ 2009 $ k describe service database-service
Name: database-service
Namespace: default
Labels: app=database
Annotations: kubectl.kubernetes.io/last-applied-configuration:
{"apiVersion":"v1","kind":"Service","metadata":{"annotations":{},"labels":{"app":"database"},"name":"database-service","namespace":"defaul...
Selector: app=database,tier=database
Type: ClusterIP
IP: None
Port: mysql 3306/TCP
TargetPort: 3306/TCP
Endpoints: <none>
Port: blazegraph 9999/TCP
TargetPort: 9999/TCP
Endpoints: <none>
Session Affinity: None
Events: <none>
Notice the service Endpoints is <none>. I am not sure this is the right setup.
Headless Service you should use in any case where you want to automatically discover all pods under the service as opposed to regular Service where you get ClusterIP instead. As an illustration from above mentioned example here is difference between DNS entries for Service (with ClusterIP) and Headless Service (without ClusterIP):
Standard service you will get the clusterIP value:
kubectl exec zookeeper-0 -- nslookup zookeeper
Server: 10.0.0.10
Address: 10.0.0.10#53
Name: zookeeper.default.svc.cluster.local
Address: 10.0.0.213
Headless service you will get IP of each pod
kubectl exec zookeeper-0 -- nslookup zookeeper
Server: 10.0.0.10
Address: 10.0.0.10#53
Name: zookeeper.default.svc.cluster.local
Address: 172.17.0.6
Name: zookeeper.default.svc.cluster.local
Address: 172.17.0.7
Name: zookeeper.default.svc.cluster.local
Address: 172.17.0.8
Now, If you connect two statefulset with single headless service, it will return the address of each pod in both the statefulset. There will be no way to differentiate the pods from two applications if you create two statefulset and one headless service for that. See the following article to understand why headless services are used
Headless service allow developer to reduce coupling from kubernetes system by allowing them to do discovery their own way. For such services, clusterIP is not allocated, kube-proxy doesn't handle these services and there is no load balancing and proxying done by platform for them. So, If you define clusterIP: None in your service there will be no load-balancing will be done from kubernetes end.
Hope this helps.
EDIT:
I did a little experiment to answer your queries, created two statefulsets of mysql database named mysql and mysql2, with 1 replica for each statefulset. They have their own PV, PVC but bound by only single headless service.
[root#ip-10-0-1-235 centos]# kubectl get pods -l app=mysql -o wide
NAME READY STATUS RESTARTS AGE IP NODE
mysql-0 1/1 Running 0 4m 192.168.13.21 ip-10-0-1-235.ec2.internal
mysql2-0 1/1 Running 0 3m 192.168.13.22 ip-10-0-1-235.ec2.internal
Now you can see the single headless service attached to both the pods
[root#ip-10-0-1-235 centos]# kubectl describe svc mysql
Name: mysql
Namespace: default
Labels: <none>
Annotations: <none>
Selector: app=mysql
Type: ClusterIP
IP: None
Port: <unset> 3306/TCP
TargetPort: 3306/TCP
Endpoints: 192.168.13.21:3306,192.168.13.22:3306
Session Affinity: None
Events: <none>
Now when you lookup the service from some other pod, it returns IP address of both the pods:
[root#rtp-worker-0 /]# nslookup mysql
Server: 10.96.0.10
Address: 10.96.0.10#53
Name: mysql.default.svc.cluster.local
Address: 192.168.13.21
Name: mysql.default.svc.cluster.local
Address: 192.168.13.22
Now, it is impossible to identify which address(pod) is of which statefulset. Now I tried to identify the statefulset using its metadata name, but couldn't
[root#rtp-worker-0 /]# nslookup mysql2.mysql.default.svc.cluster.local
Server: 10.96.0.10
Address: 10.96.0.10#53
** server can't find mysql2.mysql.default.svc.cluster.local: NXDOMAIN
Hope it clarifies.