I have created a Kubernetes cluster with 2 nodes, one Master node and one Worker node (2 different VMs).
The worker node has joined the cluster successfully, so when I run the commanad:
kubectl get nodes in my master node it appears the 2 nodes exists in the cluster!
However, when I run the command kubectl apply -f https://k8s.io/examples/controllers/nginx-deployment.yaml from my worker node terminal, in order to create a deployment in the worker node, I have the following error:
The connection to the server localhost:8080 was refused. - did you specify the right host or port?
Any help what is going on here?
It looks like you have issue with your kubeconfig file, as usually localhost:8080 is the default server to connect in absence of this file . Generally, Kubernetes uses this file to store cluster authentication information and a list of contexts to which kubectl refers when running commands - that's why kubectl can't work properly without this file.
To check the presence of kubeconfig file, enter this command: kubectl config view.
Or just check the presence of the file named config in the $HOME/.kube directory, which is the default location for kubeconfig file.
If it is absent, you would need to copy the config file to your node, e.g.:
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
sudo service kubelet restart
It is also possible to generate config file in a more difficult way - instead of copying - as described here.
The easy way to do it is to copy the config from master node usually found here : /etc/kubernetes/admin.conf , to whetever node you want to configure kubectl ( even on master node) . The location to be copied is : $HOME/.kube/config
Also, you can this command from master node by specify nodeselector or label.
Assign POD node
Related
I'm using two virtual machine with operating system Centos 8
master-node:
kubeadm init
node-1:
kubeadm join
node-1 joined successfully, and got the result run "kubectl get nodes".
but running kubectl get nodes got response "The connection to the server localhost:8080 was refused - did you specify the right host or port?"
I've checked my config using command kubectl config view and I got a result:
apiVersion: v1
clusters: null
contexts: null
current-context: ""
kind: Config
preferences: {}
users: null
I've ls /etc/kubernetes/ and it show kubelet.conf only
From what I see you are trying to use kubectl on worker node after successfull kubeadm join.
kubeadm init is genereting kubeadmin credentials/config files that are used to connect to the cluster and you were expecting that kubeadm join will also create simmilar credentials so you can run kubectl commands from worker node. kubeadm join command is not placing any admin credentials on worker nodes (where applications are running; for security reasons).
If you want it there you need to copy it from master to worker manually (or create a new ones).
Based on the writing, once kubeadm init is completed the master node is initialized and components are set.
Running kubeadm join on worker node would join this node to previous master.
After this step if you're running kubectl get nodes on master and encountering the above mentioned issue then its because cluster config is missing for kubectl.
The default config will be /etc/kubernetes/admin.conf which can set to environmental variables with key as KUBECONFIG.
Or simplest way would be to copy this file into .kube folder.
cp -f /etc/kubernetes/admin.conf ~/.kube/config
Running under Ubuntu I used kubeadm init to setup my cluster (master node) and copied over the /etc/kubernetes/admin.conf $HOME/.kube/config and all was well when using kubectl.
However after a reboot my master node has had an IP address change which is not the same as what is in $HOME/.kube/config so now I can no longer connect kubectl
So how do I regenerate the admin.conf now that I have a new IP address? Running kubeadm init will just kill everything which is not what I want.
I found this solution on the internet and it works for me:
systemctl stop kubelet docker
cd /etc/
mv kubernetes kubernetes-backup
mv /var/lib/kubelet /var/lib/kubelet-backup
mkdir -p kubernetes
cp -r kubernetes-backup/pki kubernetes
rm kubernetes/pki/{apiserver.*,etcd/peer.*}
systemctl start docker
kubeadm init --ignore-preflight-errors=DirAvailable--var-lib-etcd
#Run "kubeadm reset" on all nodes if was this error "error execution phase preflight: [preflight] Some fatal errors occurred:
[ERROR FileAvailable--etc-kubernetes-kubelet.conf]: /etc/kubernetes/kubelet.conf already exists
[ERROR Port-10250]: Port 10250 is in use
[ERROR FileAvailable--etc-kubernetes-pki-ca.crt]: /etc/kubernetes/pki/ca.crt already exists"
cp kubernetes/admin.conf ~/.kube/config
kubectl get nodes --sort-by=.metadata.creationTimestamp
kubectl delete node $(kubectl get nodes -o jsonpath='{.items[(#.status.conditions[0].status=="Unknown")].metadata.name}')
kubectl get pods --all-namespaces
After These, Join your Slaves to Master.
Reference: https://medium.com/#juniarto.samsudin/ip-address-changes-in-kubernetes-master-node-11527b867e88
The following command can be used to regenerate admin.conf
kubeadm alpha phase kubeconfig admin --apiserver-advertise-address <new_ip>
However, if you use an IP instead of a hostname, your API-server certificate will be invalid. So, either regenerate your certs ( kubeadm alpha phase certs renew apiserver ), use hostnames instead of IPs or add the insecure --insecure-skip-tls-verify flag when using kubectl
You do not want to use kubeadm reset. That will reset everything and you would have to start configuring your cluster again.
Well, in your scenario, please have a look on the steps below:
nano /etc/hosts (update your new IP against YOUR_HOSTNAME)
nano /etc/kubernetes/config (configuration settings related to your cluster) here in this file look for the following params and update accordingly
KUBE_MASTER="--master=http://YOUR_HOSTNAME:8080"
KUBE_ETCD_SERVERS="--etcd-servers=http://YOUR_HOSTNAME:2379" #2379 is default port
nano /etc/etcd/etcd.conf (conf related to etcd)
KUBE_ETCD_SERVERS="--etcd-servers=http://YOUR_HOSTNAME/WHERE_EVER_ETCD_HOSTED:2379"
2379 is default port for etcd. and you can have multiple etcd servers defined here comma separated
Restart kubelet, apiserver, etcd services.
It is good to use hostname instead of IP to avoid such scenarios.
Hope it helps!
I have deployed Kubernetes using the link Kubernetes official page
I see that Kubernetes is deployed because in the end i got this
Your Kubernetes master has initialized successfully!
To start using your cluster, you need to run the following as a regular user:
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
https://kubernetes.io/docs/concepts/cluster-administration/addons/
You can now join any number of machines by running the following on each node
as root:
kubeadm join 172.16.32.101:6443 --token ma1d4q.qemewtyhkjhe1u9f --discovery-token-ca-cert-hash sha256:408b1fdf7a5ea5f282741db91ebc5aa2823802056ea9da843b8ff52b1daff240
when i do kubectl get pods it thorws this error
# kubectl get pods
The connection to the server 127.0.0.1:6553 was refused - did you specify the right host or port?
When I do see the cluster-info it says as follows
kubectl cluster-info
Kubernetes master is running at https://127.0.0.1:6553
But when i see the config it shows as follows
apiVersion: v1
clusters:
- cluster:
certificate-authority-data: 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
**server: https://172.16.32.101:6443**
Even telnet shows that there is a process running on 6443 but not on 6553
how can change the port and how can I fix the issue??
Any help would be of great use
Thanks in advance.
It looks like your last kubectl config interferes with the previous clusters configurations.
It is possible to have settings for several different clusters in one .kube/config or in separate files.
But in some cases, you may want to manage only the cluster you've just created.
Note: After tearing down the exited cluster using kubeadm reset followed by initializing fresh cluster using kubeadm init, new certificates will be generated. To operate the new cluster, you have to update kubectl configuration or replace it with the new one.
To clean up old kubectl configurations and apply the last one, run the following commands:
rm -rf $HOME/.kube
unset KUBECONFIG
# Check if you have KUBECONFIG configured in profile dot files and comment or remove it.
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
It gives you up-to-date configuration for the last cluster you've created using kubeadm tool.
Note: You should copy kubectl configuration for all users accounts which you are going to use to manage the cluster.
Here are some examples of how to manage config file using the command line.
I figured out the issue it is because of the firewall in the machine I could join nodes to the cluster once I allowed traffic via port 6443. I didn't fix the issue with this post but for beginners use this K8's on AWS for a better idea.
Thanks for the help guys...!!!
On my master node
root#k8smaster:~# kubectl get nodes
The connection to the server localhost:8080 was refused - did you specify the right host or port?
root#k8smaster:~# exit
logout
yoda#k8smaster:~/bin$ kubectl get nodes
NAME STATUS ROLES AGE VERSION
k8smaster Ready master 5d v1.9.2
k8sworker Ready <none> 51s v1.9.2
Why do I need to run kubectl as my own user ?
What Michael said is exactly accurate; kubectl looks in the current user's home directory, which for yoda will likely be /home/yoda but for root is almost certainly /root.
You can very quickly test this theory by re-running your kubectl command with an explicit --kubeconfig ~yoda/.kube/config:
kubectl --kubeconfig ~yoda/.kube/config get nodes
You can also export the shell variable KUBECONFIG to avoid having to constantly include that long --kubeconfig syntax:
export KUBECONFIG=~yoda/.kube/config
kubectl get nodes
Ensure you don't put any characters between the ~ and yoda or it will look for a yoda directory inside the current user's home directory.
kubectl needs kubeconfig at $HOME/.kube/config by default.
Kubeadm puts the original kubeconfig in /etc/kubernetes/admin.conf.
Any user (including root) can do the following to get kubeconfig in the current user's home directory at $HOME/.kube/config:
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
Alternatively, if you are the root user, you can run this:
export KUBECONFIG=/etc/kubernetes/admin.conf
Running kubectl get pods with sudo:
sudo kubectl get pods
The connection to the server localhost:8080 was refused - did you specify the right host or port?
Running as a normal user:
kubectl get pods
No resources found.
By default, kubectl looks in ~/.kube/config (or the file pointed to be $KUBECONFIG) to determine what server to connect to. Your home directory and environment are different when running commands as root. When no connection info is found, kubectl defaults to localhost:8080
You would have run these commands from the normal user :
sudo cp /etc/kubernetes/admin.conf $HOME/
sudo chown $(id -u):$(id -g) $HOME/admin.conf
export KUBECONFIG=$HOME/admin.conf
which would have copied config file in your normal user home directory and that is why you are able to get to the connection from the normal host and not from sudo.