I have install kubeadm in master and connected 2 worker node to it, after that i deploy nginx pod and ssh into that nginx pod after that i type nslookup google.com or apt update its not working got connection timeout it think due its not connecting to internet. How to solve it, The 3 VM is running in azure portal and 3 VM are connected to together. kubectl v1.24.2 im using it
The 3 VM is running in azure portal and 3 VM are connected to together. kubectl v1.24.2 im using it and calico network also im using
nginx pod is running in worker2 and services of containerd container runtime/Docker Application Container Engine both are in running state. if i type lsmod | grep br_netfilter i got
br_netfilter 28672 0
bridge 266240 1 br_netfilter
here is my nginx.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx
spec:
replicas: 1
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx
ports:
- containerPort: 80
# command: ["/bin/sh","-c"]
# args: ["apt update"]
# securityContext:
# privileged: true
---
apiVersion: v1
kind: Service
metadata:
name: nginx
labels:
app: nginx
spec:
type: ClusterIP
selector:
app: nginx
ports:
- port: 8080
targetPort: 80
name: nginx-http
And Here is the screenshot of coredns install in kube-system naming space
Seems like name is not resolving, please check if coredns is working properly. You can break down the issue like this:
from inside the pod first check you have network reachability to the internet: curl -v telnet://8.8.8.8:53
check you have connectivity to core DNS: curl -v telnet://coredns_service_name:53 or curl -v telnet://coredns_cluster_ip:53
I am trying to run web application developed using Java, Jsp, Servlet, Angularjs and Jquery on K8s cluster.
While login into the application line which have request.getCookies() or request.getSession() hit, it is returning null and then it will throw NullPointerException. This exception is not allow me to login in to the application.
I have tried running the same application in local machine and on azure using docker and it is working fine. This confirms there is no issue in image . Following command used to run on docker,
docker run -p 8080:8080 <image_name>
I am using k8s on Azure(Azure kubernates service) and following is the configuration I have used.
apiVersion: v1
kind: Service
metadata:
labels:
app: app
namespace: default
name: app
spec:
ports:
- port: 8080
protocol: TCP
targetPort: 8080
name: http
selector:
app: app
type: LoadBalancer
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: app
spec:
replicas: 1
selector:
matchLabels:
app: app
strategy:
type: Recreate
template:
metadata:
labels:
app: app
spec:
containers:
- image: <image_name>
name: app
imagePullPolicy: Always
ports:
- containerPort: 8080
name: app
All the pods, services and ingress are running normally without restarting or throwing any exception.
I tried creating ingress as well, but issue is still same. Following configuration I have used to create an ingress and also changed service.spec.type to NodePort before deploying the ingress.
apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
name: gateway-app
annotations:
nginx.ingress.kubernetes.io/rewrite-target: /
spec:
rules:
- http:
paths:
- path: /app/*
backend:
serviceName: app
servicePort: 8080
Please guide here how can we run applications with sessions and cookies on k8s cluster.
Hi All,
My node.js app is failing while I am trying to deploy it in Kubernetes using a docker image. The container in Kubernetes pod is getting created but it's immediately getting terminated, after executing the command "npm start" Here is the content of my dockerfile:
FROM node:13.12.0-alpine
WORKDIR /app
ENV PATH /app/node_modules/.bin:$PATH
COPY nodejs/package.json ./
RUN npm install
RUN npm update
COPY nodejs/ .
COPY . ./
CMD ["npm", "start"]
Here is the content of the yaml file:
kind: Service
apiVersion: v1
metadata:
name: nodejs-service
spec:
selector:
app: nodejs
type: NodePort
ports:
- port: 3000
targetPort: 3000
nodePort: 30016
selector:
app: nodejs
---
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app: nodejs
name: nodejs-deployment
spec:
replicas: 1
selector:
matchLabels:
app: nodejs
template:
metadata:
labels:
app: nodejs
spec:
containers:
- image: 336319716199.dkr.ecr.ap-south-1.amazonaws.com/ddp/nodejs-frontend:106
name: frontend-nodejs
command: ["npm", "start"]
ports:
- containerPort: 3000
Any suggestion will be highly appreciated ! Thanks in advance !
I am new to the world of Kubernetes and was testing a sample Django "Hello world" app deployment. Using docker-compose I was able to access the hell world page on a browser but I need to use Kubernetes. So I tested two options and none of them worked.
1) I created an Azure CICD pipeline to build and push the image in ACR using the following Dockerfile,
FROM python:3.8
ENV PYTHONDONTWRITEBYTECODE 1
ENV PYTHONUNBUFFERED 1
RUN mkdir /hello_world
WORKDIR /hello_world
COPY . /hello_world/
RUN pip install -r requirements.txt
CMD [ "python", "manage.py", "runserver", "0.0.0.0:8000" ]
The pipeline completes successfully and uploads the image in the repository.
Now I use kubectl to deploy using the deployment file,
apiVersion: apps/v1
kind: Deployment
metadata:
name: django-helloworld
spec:
replicas: 3
selector:
matchLabels:
app: django-helloworld
template:
metadata:
labels:
app: django-helloworld
spec:
containers:
- name: django-helloworld
image: acrshgpdev1.azurecr.io/django-helloworld:194
#imagePullPolicy: Always
ports:
- containerPort: 8000
---
apiVersion: v1
kind: Service
metadata:
name: django-helloworld-service
spec:
type: LoadBalancer
ports:
- port: 80
selector:
app: django-helloworld
The deployment and service are created but when I try to access the external IP of the LB service through a browser the page is inaccessible. I used the external ip:port and it didn't work.
Any thoughts why would this be happening?
2) I used the same Dockerfile but a different deployment file(changed the image to the locally created image & removed LB service) to deploy the app to my local Kubernetes. the deployment file was as follows,
apiVersion: v1
kind: Service
metadata:
name: django-helloworld-service
spec:
selector:
app: django-helloworld
ports:
- protocol: TCP
port: 80
targetPort: 30800
type: NodePort
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: django-helloworld
spec:
replicas: 3
selector:
matchLabels:
app: django-helloworld
template:
metadata:
labels:
app: django-helloworld
spec:
containers:
- name: django-helloworld
image: django-helloworld:1.0
#imagePullPolicy: Always
ports:
- containerPort: 8000
It creates the deployment and service but doesn't assign an external IP to the NodePort service so I am not able to figure out what service should I choose to test the app is successful. I know I can't choose a LB as it doesn't go locally and I need to deploy using a cloud service.
just configure your service to be of type LoadBalancer and do a proper port mapping:
apiVersion: v1
kind: Service
metadata:
name: django-helloworld-service
spec:
type: LoadBalancer
ports:
- port: 80
targetPort: 8000
selector:
app: django-helloworld
https://kubernetes.io/docs/concepts/services-networking/service/
Make sure the deployment has associated healthy pods too (they show as Running and with 1/1 next to their name). If there aren't, make sure your cluster can successfully pull from acrshgpdev1.azurecr.io registry; you can integrate directly an AKS cluster with an ACR registry following this article:
az aks update -n myAKSCluster -g myResourceGroup --attach-acr acrshgpdev1.azurecr.io
or by adding the SP of the AKS cluster manually to the Reader role on the ACR.
I have a very simple node.js application (HTTP service), which "talks" to redis. I want to create a deployment and run it with minikube.
From my understanding, I need a kubernetes Pod for my app, based on the docker image. Here's my Dockerfile:
FROM node:8.9.1
WORKDIR /usr/src/app
COPY package*.json ./
RUN npm install
COPY . .
EXPOSE 8080
CMD ["npm", "start"]
I build the docker image with docker build -t my-app .
Next, I created a Pod definition for my app's Pod:
apiVersion: v1
kind: Pod
metadata:
name: my-app
spec:
containers:
- name: my-app
image: my-app:latest
imagePullPolicy: Never
ports:
- containerPort: 8080
So far, so good. But from now on, I have no clear idea how to proceed with redis:
should redis be another Pod, or a Service (in terms of Kubernetes kind)?
How do I reference redis from inside my app? Based on whether redis will be defined as a Pod/Service, how do I obtain a connection URL and port? I read about environment variables being created by Kubernetes, but I am not sure whether these work for Pods or Services.
How do I aggregate both (my app & redis) under single configuration? How do I make sure that redis starts first, then my app (which requires running redis instance), and how do I expose my HTTP endpoints to the "outside world"? I read about Deployments, but I am not sure how to connect these pieces together.
Ideally, I would like to have all configurations inside YAML files, so that at the end of the day the whole infrastructure could be started with a single command.
I think I figured out a solution (using a Deployment and a Service).
For my deployment, I used two containers (webapp + redis) within one Pod, since it doesn't make sense for a webapp to run without active redis instance, and additionally it connects to redis upon application start. I could be wrong in this reasoning, so feel free to correct me if you think otherwise.
Here's my deployment:
apiVersion: apps/v1
kind: Deployment
metadata:
name: my-app-deployment
spec:
selector:
matchLabels:
app: my-app-deployment
template:
metadata:
labels:
app: my-app-deployment
spec:
containers:
- name: redis
image: redis:latest
ports:
- containerPort: 6379
volumeMounts:
- mountPath: /srv/www
name: redis-storage
- name: my-app
image: my-app:latest
imagePullPolicy: Never
ports:
- containerPort: 8080
volumes:
- name: redis-storage
emptyDir: {}
And here's the Service definition:
apiVersion: v1
kind: Service
metadata:
name: my-app-service
spec:
ports:
- port: 8080
protocol: TCP
type: NodePort
selector:
app: my-app-deployment
I create the deployment with:
kubectl create -f deployment.yaml
Then, I create the service with kubectl create -f service.yaml
I read the IP with minikube ip and extract the port from the output of kubectl describe service my-app-service.
I agree with all of the previous answers. I'm just trying to things more simple by executing a single command.
First, create necessary manifests for redis in a file say redis.yaml and service to expose it outside.
apiVersion: v1
kind: Service
metadata:
name: redis
labels:
app: node-redis
spec:
ports:
- name: redis
port: 6379
targetPort: 6379
type: NodePort
selector:
app: node-redis
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: redis
spec:
selector:
matchLabels:
app: node-redis
replicas: 1
template:
metadata:
labels:
app: node-redis
spec:
containers:
- name: redis
image: redis:latest
imagePullPolicy: IfNotPresent
ports:
- containerPort: 6379
# data volume where redis writes data
volumeMounts:
- name: data
mountPath: /data
readOnly: false
volumes:
- name: data
persistentVolumeClaim:
claimName: redis-data
---
# data volume
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: redis-data
labels:
app: node-redis
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 100Mi
Next put manifests for your app in another file say my-app.yaml. Here i put the volume field so that you can use the data that stored by redis.
apiVersion: v1
kind: Pod
metadata:
name: my-app
labels:
app: node-redis
spec:
containers:
- name: my-app
image: my-app:latest
ports:
- containerPort: 8080
# data volume from where my-app read data those are written by redis
volumeMounts:
- name: data
mountPath: /data
readOnly: false
volumes:
- name: data
persistentVolumeClaim:
claimName: redis-data
Now we can use the following bash file my-app.sh.
#!/bin/bash
kubectl create -f redis.yaml
pod_name=$(kubectl get po -l app=node-redis | grep app-with-redis | awk '{print $1}')
# check whether redis server is ready or not
while true; do
pong=$(kubectl exec -it $pod_name -c redis redis-cli ping)
if [[ "$pong" == *"PONG"* ]]; then
echo ok;
break
fi
done
kubectl create -f my-app.yaml
Just run chmod +x my-app.sh; ./my-app.sh to deploy. To get the url run minikube service redis --url. You can similarly get the url for your app. The only thing is you need a nodePort type service for your app to access it from outside of the cluster.
So, everything is in your hand now.
I would run redis in a separate pod (i.e.: so your web app doesn't take down the redis server if itself crashes).
Here is your redis deployment & service:
deployment.yaml:
apiVersion: apps/v1
kind: Deployment
metadata:
name: redis
spec:
selector:
matchLabels:
app: redis
replicas: 1
template:
metadata:
labels:
app: redis
spec:
volumes:
- name: host-sys
hostPath:
path: /sys
initContainers:
- name: disable-thp
image: redis:4.0-alpine
volumeMounts:
- name: host-sys
mountPath: /host-sys
command: ["sh", "-c", "echo never > /host-sys/kernel/mm/transparent_hugepage/enabled"]
containers:
- name: redis
image: redis:4.0-alpine
imagePullPolicy: IfNotPresent
resources:
requests:
cpu: 350m
memory: 1024Mi
ports:
- containerPort: 6379
service.yaml:
apiVersion: v1
kind: Service
metadata:
name: redis
labels:
app: redis
spec:
ports:
- port: 6379
name: redis
selector:
app: redis
Since we've exposed a kubernetes Service you can then access your redis instance by hostname, or it's "service name", which is redis.
You can check out my kubernetes redis repository at https://github.com/mateothegreat/k8-byexamples-redis. You can simply run make install if you want the easier route.
Good luck and if you're still stuck please reach out!
yes you need a separete deployement and service for redis
use kubernetes service discovery , should be built in , KubeDNS , CoreDNS
use readniness and liveness probes
Yes , you can write a single big yaml file to describe all the deployments and services. then:
kubectl apply -f yourfile.yml
or you can place the yaml in separate files and then do the :
kubectl apply -f dir/
I recommend you to read further the k8s docs, but in general re your questions raised above:
Yes another pod (with the relevant configuration) and an additional service depends on your use case, check this great example: https://kubernetes.io/docs/tutorials/configuration/configure-redis-using-configmap/
Using services, read more here: https://kubernetes.io/docs/concepts/services-networking/connect-applications-service/
There are several ways to manage dependencies - search for deployment dependencies, but in general you can append them in the same file with readiness endpoint and expose using a Service - read more in the link in bullet 2