I'm new to k8s and I'm trying to build a distributed system. The idea is that a stateful pod will be spawened for each user.
Main services are two Python applications MothershipService and Ship. MothershipService's purpose is to keep track of ship-per-user, do health checks, etc. Ship is running some (untrusted) user code.
MothershipService Ship-user1
| | ---------- | |---vol1
|..............| -----. |--------|
\
\ Ship-user2
'- | |---vol2
|--------|
I can manage fine to get up the ship service
> kubectl get all -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
pod/ship-0 1/1 Running 0 7d 10.244.0.91 minikube <none> <none>
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE SELECTOR
service/ship ClusterIP None <none> 8000/TCP 7d app=ship
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 7d <none>
NAME READY AGE CONTAINERS IMAGES
statefulset.apps/ship 1/1 7d ship ship
My question is how do I go about testing this via curl or a browser? These are all backend services so NodePort seems not the right approach since none of this should be accessible to the public. Eventually I will build a test-suite for all this and deploy on GKE.
ship.yml (pseudo-spec)
kind: Service
metadata:
name: ship
spec:
ports:
- port: 8000
name: ship
clusterIP: None # headless service
..
---
kind: StatefulSet
metadata:
name: ship
spec:
serviceName: "ship"
replicas: 1
template:
spec:
containers:
- name: ship
image: ship
imagePullPolicy: IfNotPresent
ports:
- containerPort: 8000
name: ship
..
CodePudding user response：
One possibility is to use the kubectl port-forward command to expose the pod port locally on your system. For example, if I'm use this deployment to run a simple web server listening on port 8000:
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app: example
name: example
spec:
selector:
matchLabels:
app: example
template:
metadata:
labels:
app: example
spec:
containers:
- args:
- --port
- "8000"
image: docker.io/alpinelinux/darkhttpd
name: web
ports:
- containerPort: 8000
name: http
I can expose that on my local system by running:
kubectl port-forward deploy/example 8000:8000
As long as that port-forward command is running, I can point my browser (or curl) at http://localhost:8000 to access the service.
Alternately, I can use kubectl exec to run commands (like curl or wget) inside the pod:
kubectl exec -it web -- wget -O- http://127.0.0.1:8000
CodePudding user response：
Example process on how to create a Kubernetes Service object that exposes an external IP address :
**Creating a service for an application running in five pods: **
Run a Hello World application in your cluster:
kubectl run hello-world --replicas=5 --labels="run=load-balancer-example" --image=gcr.io/google-samples/node-hello:1.0 --port=8080
The preceding command creates a Deployment object and an associated ReplicaSet object. The ReplicaSet has five Pods, each of which runs the Hello World application.
Display information about the Deployment:
kubectl get deployments hello-world
kubectl describe deployments hello-world
Display information about your ReplicaSet objects:
kubectl get replicasets
kubectl describe replicasets
Create a Service object that exposes the deployment:
kubectl expose deployment hello-world --type=LoadBalancer --name=my-service
Display information about the Service:
kubectl get services my-service
The output is similar to this:
NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE
my-service 10.3.245.137 104.198.205.71 8080/TCP 54s
Note: If the external IP address is shown as , wait for a minute and enter the same command again.
Display detailed information about the Service:
kubectl describe services my-service The output is similar to this:
Name: my-service
Namespace: default
Labels: run=load-balancer-example
Selector: run=load-balancer-example
Type: LoadBalancer
IP: 10.3.245.137
LoadBalancer Ingress: 104.198.205.71
Port: <unset> 8080/TCP
NodePort: <unset> 32377/TCP
Endpoints: 10.0.0.6:8080,10.0.1.6:8080,10.0.1.7:8080 2 more...
Session Affinity: None
Events: Make a note of the external IP address exposed by your service. In this example, the external IP address is 104.198.205.71. Also note the value of Port. In this example, the port is 8080.
In the preceding output, you can see that the service has several endpoints: 10.0.0.6:8080,10.0.1.6:8080,10.0.1.7:8080 2 more. These are internal addresses of the pods that are running the Hello World application. To verify these are pod addresses, enter this command:
kubectl get pods --output=wide
The output is similar to this:
NAME ... IP NODE
hello-world-2895499144-1jaz9 ... 10.0.1.6 gke-cluster-1-default-pool-e0b8d269-1afc
hello-world-2895499144-2e5uh ... 0.0.1.8 gke-cluster-1-default-pool-e0b8d269-1afc
hello-world-2895499144-9m4h1 ... 10.0.0.6 gke-cluster-1-default-pool-e0b8d269-5v7a
hello-world-2895499144-o4z13 ... 10.0.1.7 gke-cluster-1-default-pool-e0b8d269-1afc
hello-world-2895499144-segjf ... 10.0.2.5 gke-cluster-1-default-pool-e0b8d269-cpuc
Use the external IP address to access the Hello World application:
curl http://<external-ip>:<port>
where <external-ip> is the external IP address of your Service, and <port> is the value of Port in your Service description.
The response to a successful request is a hello message:
Hello Kubernetes!
Please refer to How to Use external IP in GKE and Exposing an External IP Address to Access an Application in a Cluster for more information.