I have local and dockerized apps which are working excelent on localhost : java backend at 8080, angular at 4200, activemq at 8161, and postgres on 5432
Now,I am trying also to kubernetize apps to make them work on localhosts.
As far as I know kubernetes provides random Ip on clusters, what should I do do make them work on localhosts to listen to each other ? Is there any way to make them automatically start at those localhosts instead of using port forwariding for each service ?
Every service and deployment has similiar structure :
apiVersion: v1
kind: Service
metadata:
name: backend
spec:
selector:
app: backend
type: LoadBalancer
ports:
- protocol: 8080
port: 8080
targetPort: 8080
Deployment
apiVersion: apps/v1
kind: Deployment
metadata:
name: backend
labels:
app: backend
spec:
replicas: 3
selector:
matchLabels:
app: backend
template:
metadata:
labels:
app: backend
spec:
containers:
- name: backend
image:
ports:
- containerPort: 8080
Tried port-forwarding, works, but requires lot of manual work ( open few new powershell windows and then do manual port forwarding)
In the kubernetes eco system apps talk to each other through their services.
If they are in the same namespace they can directly go to the service name of not they need to specify the full name which includes the namespace name:
my-svc.my-namespace.svc.cluster-domain.example
Never mind, find a way to do it automaticaly with port - forwarding, with simply running 1 script
I have wrote a .bat script with these steps:
kubernetes run all deployments file
kubernetes run all services file
15 second timeout to give time to change pod state from pending to running
{ do port forwarding for each service. Every forwarding is in new powershell windows without exiting }
Related
I have created a very simple spring boot application with only one REST service. This app is converted into a docker image ("springdockerimage:1") and deployed in the Kubernetes cluster with 3 replicas. Contents of my "Deployment" definition is as follows:
apiVersion: apps/v1
kind: Deployment
metadata:
name: springapp
labels:
app: distributiondemo
spec:
selector:
matchLabels:
app: distributiondemo
replicas: 3
template:
metadata:
labels:
app: distributiondemo
spec:
containers:
- name: spring-container
image: springdockerimage:1
I have created service for my above deployment as follows:
apiVersion: v1
kind: Service
metadata:
name: springservice
labels:
app: distributiondemo
spec:
selector:
app: distributiondemo
ports:
- port: 8080
protocol: TCP
targetPort: 8080
name: spring-port
nodePort: 32000
type: NodePort
After deploying both the above YAML(deployment and service) files, I noticed that everything has been deployed as expected i.e., 3 replicas are created and my service is having 3 endpoints as well. Below screenshot is the proof of the same:
Since I am using minikube for my local testing, I am port forwarding and accessing the application as kubectl port-forward deployment.apps/springapp 40002:8080 .
But one thing I noticed is that all my HTTP requests are getting redirected to only one pod.
while true ; do curl http://localhost:40002/docker-java-app/test ;done
I am not getting where exactly I am doing it wrong. Any help would be appreciated. Thank you.
The loadbalancing might not work with port-forwarded ports as it might be directly redirecting traffic to pod (read more here). The K8s service is the feature will give you that loadbalancing capability.
So you can try either of below instead
Use http://your_service_dns_name:8080/docker-java-app/test
Use http://service_cluster_ip:8080/docker-java-app/test
Use http://any_host_ip_from_k8s_cluster:32000/docker-java-app/test
Option 1 and 2 works only if you are accessing those urls from a host which is part of K8s cluster. Option 3 just needs connectivity to target host and port, from the host you are accessing url.
I have two k8s deployments in one cluster GKE, for one web application, one is frontend(react) and the other is backend(python), the frontend is working fine but when I try to do something on the frontend that calls the backend i got this , I have ingress for the frontend, which works perfectly, the only thing i can't figure it out is why the frontend can't reach the backend, i want them to communicate via services. I have the following services:
Frontend service
apiVersion: v1
kind: Service
metadata:
name: frontend
spec:
selector:
app: hello
tier: frontend
ports:
- protocol: "TCP"
port: 80
targetPort: 3000
Backend service
apiVersion: v1
kind: Service
metadata:
name: backend
spec:
selector:
app: hello
tier: backend
track: stable
ports:
- protocol: TCP
port: 80
targetPort: 8000
Any fix suggestions?
When the applications are client side applications like react or Angular, the application runs on the client browser; not in the server side. In that case, the application in the client browser must invoke the APIs on the server (backend application).
In such a situation, even though the application is named backend; it must expose the APIs via the Ingress so that those APIs can be used by the frontend application running on the client browser.
I have a very simple Python app that works fine when I execute uvicorn main:app --reload. When I go to http://127.0.0.1:8000 on my machine, I'm able to interact with the API. (My app has no frontend, it is just an API built with FastAPI). However, I am trying to deploy this via Kubernetes, but am not sure how I can access/interact with my API.
Here is my deployment.yaml.
apiVersion: apps/v1
kind: Deployment
metadata:
name: my-deployment
spec:
selector:
matchLabels:
app: nginx
replicas: 1
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.16.1
ports:
- containerPort: 80
When I enter kubectl describe deployments my-deployment in the terminal, I get back a print out of the deployment, the namespace it is in, the pod template, a list of events, etc. So, I am pretty sure it is properly deployed.
How can I access the application? What would the url be? I have tried a variety of localhost + port combinations to no avail. I am new to kubernetes so I'm trying to understand how this works.
Update:
apiVersion: apps/v1
kind: Deployment
metadata:
name: app-deployment
namespace: default
spec:
selector:
matchLabels:
app: web
replicas: 2
template:
metadata:
labels:
app: web
spec:
containers:
- name: site
image: nginx:1.16.1
ports:
- containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
name: app-entrypoint
namespace: default
spec:
type: NodePort
selector:
app: web
ports:
- port: 80
targetPort: 80
nodePort: 30001
Again, when I use the k8s CLI, I'm able to see my deployment, yet when I hit localhost:30001, I get an Unable to connect message.
You have given containerPort: 80 but if your app listens on port 8080 change it to 8080.
There are different ways to access an application deployed on kubernetes
Port Forward using kubectl port-forward deployment/my-deployment 8080:8080
Creare a NodePort service and use http://<NODEIP>:<NODEPORT>
Create a LoadBalanceer service. This works only in supported cloud environment such as AWS, GKE etc.
Use ingress controller such nginx to expose the application.
By Default k8s application are exposed only within the cluster, if you want to access it from outside of the cluster then you can select any of the below options:
Expose Deployment as a node port service (kubectl expose deployment my-deployment --name=my-deployment-service --type=NodePort), describe the service and get the node port assigned to it (kubectl describe svc my-deployment-service). Then try http://<node-IP:node-port>/
For production grade cluster the best practice is to use LoadBalancer type (kubectl expose deployment my-deployment --name=my-deployment-service --type=LoadBalancer --target-port=8080) as part of this service you get an external IP which can be used to access your service http://EXTERNAL-IP:8080/
You can also see the details about the endpoint using kubectl get ep
Thanks,
I am trying to setup a very simple monitoring cluster for my k8s cluster. I have successfully created prometheus pod and is running fine.
When I tried to create grafana pod the same way, its not accessible through the node port.
My Grafana deploy file is-
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: grafana-deployment
namespace: monitoring
spec:
replicas: 1
template:
metadata:
labels:
app: grafana-server
spec:
containers:
- name: grafana
image: grafana/grafana:5.1.0
ports:
- containerPort: 3000
And Service File is --
apiVersion: v1
kind: Service
metadata:
name: grafana-service
namespace: monitoring
spec:
selector:
app: grafana-server
type: NodePort
ports:
- port: 3000
targetPort: 3000
Note- When I am creating a simple docker container on the same host using same image, its working fine.
I have come to know that my servers provider had not enabled these ports (like grafana-3000, kibana-5601). Never thought of this since i am using these servers from quite a long time and never faced such blocker. They implemented these rules recently.
Well, after some port approvals, I tried the same config again and it worked like a charm.
I'm trying to expose my Deployment to a port which I can access through my local computer via Minikube.
I have tried two YAML configurations (one a load balancer, one just a service exposing a port).
I: http://pastebin.com/gL5ZBZg7
apiVersion: v1
kind: Service
metadata:
name: bot
labels:
app: bot
spec:
type: LoadBalancer
ports:
- port: 8000
targetPort: 8000
protocol: TCP
selector:
app: bot
II: http://pastebin.com/sSuyhzC5
apiVersion: v1
kind: Service
metadata:
name: bot
labels:
app: bot
spec:
ports:
- port: 8000
targetPort: 8000
protocol: TCP
selector:
app: bot
The deployment and the docker container image both expose port 8000, and the Pod is tagged with app:bot.
The first results in a service with a port which never finishes, and the external IP never gets assigned.
The second results in a port of bot:8000 TCP, bot:0 TCP in my dashboard and when I try "minikube service bot" nothing happens. The same happens if I type in "kubectl expose service bot".
I am on Mac OS X.
How can I set this up properly?
The LoadBalancer service is meant for Cloud providers and not really relevant for minikube.
From the documentation:
On cloud providers which support external load balancers, setting the type field to "LoadBalancer" will provision a load balancer for your Service.
Using a Service of type NodePort (see documentation) as mentioned in the Networking part of the minikube documentation is the intended way of exposing services on minikube.
So your configuration should look like this:
apiVersion: v1
kind: Service
metadata:
name: bot
labels:
app: bot
spec:
type: NodePort
ports:
- port: 8000
targetPort: 8000
nodePort: 30356
protocol: TCP
selector:
app: bot
And access your application through:
> IP=$(minikube ip)
> curl "http://$IP:30356"
Hope that helps.
Minikube now has the service command to access a service.
Use kubectl service <myservice>.
That will give you a URL which you can use to talk to the service.