Now i did three things：
First, install kubectl on one linux machine,
Second, copy the admin.conf file from the remote k8s server to the ~/.kube/ file on the linux host,
Third, running kubectl get nodes under Linux reports an error. .
wanlei#kf-test:~/.kube$ kubectl get nodes
The connection to the server localhost:8080 was refused - did you specify the right host or port?
I want to know what steps I have missed. .
The goal is to use kubectl from my linux host to manage k8s on the remote host
You need to place the kubeconfig file at .kube/config location i.e there should be a file with name config at .kube directory.That's where kubectl looks for the kubeconfig file by default.
Alternative to above would be defining KUBECONFIG environment variable to point to a kubeconfig file in a different location.
Related
I have a .pcap file on the master node, which I want to view in Wireshark on the local machine. I access the Kubernetes cluster via the Kops server by ssh from the local machine. I checked kubectl cp --help but provides a way to cp a file from remote pod to kops server.
If anyone knows how to bring a file from Master Node -> Kops Server -> Local machine, please share your knowledge! Thanks!
Solution is simple - scp, thanks to #OleMarkusWith's quick response.
All I did was:
On Kops Server:
scp admin#<master-node's-external-ip>:/path/to/file /dest/path
On local machine:
scp <kops-server-ip>:/path/to/file /dest/path
I'm currently using minikube and I'm trying to access my application by utilizing the minikube tunnel since the service type is LoadBalancer.
I'm able to obtain an external IP when I execute the minikube tunnel, however, when I try to check it on the browser it doesn't work. I've also tried Postman and curl, they both don't work.
To add to this, if I shell into the pod I can use curl and it does work. Furthermore, I executed kubectl port-forward and I was able to access my application through localhost.
Does anyone have any idea as to why I'm not being able to access my application even though everything seems to be running correctly?
Your service is probably bound to localhost. Minikube starts the cluster in a VM or docker (depending on the driver you are using) that is bound to an external IP, $(minikube ip).
When you are running a minikube tunnel you're tunneling from minikube cluster external IP to the internal IP of the load balancer, the LB service in Kubernete the External IP goes from "Pending" to an actual internal IP and something like this should work:
curl -H 'Host: localhost' -v $(minikube ip)
However, it doesn't in the browser, since in the above command you are sending the request to the minikube's IP, not localhost. What I do for this to work is a ssh tunnel like this one:
ssh -i $(minikube ssh-key) docker#$(minikube ip) -L 8008:localhost:80
This maps the LB listener in port 80, in minikube's cluster, to 8008 in localhost. The external IP of the service remains pending but it works since the Kube controller can still find it. If you want to map port 80 then you will need to add sudo.
If the version of ssh on your system (the one in your path) is less than 8.0, 'minikube tunnel' will silently fail to instantiate the ssh tunnel for some port forwards. (e.g. privileged ports)
Open a command prompt as administrator, and type 'where.exe ssh'. Navigate to that location in windows explorer, and right-click on 'ssh.exe'. Choose Properties->Details to see the version.
If this is less than version 8.0 you must upgrade that to at least version 8.0 to prevent this silent failure of ssh by 'minikube tunnel'.
After upgrading, ssh, ensure that the newer version is the one that will be executed by using the 'where.exe' command again. If there are two on your system, then reorder the paths in your path environment variable. Restart your shell (or better) reboot the system so that all processes environments pick up the path changes.
Then try 'minikube tunnel' again. When it is working, you should see an ssh instance in the task manager for each tunnel that minikube creates.
In my case minikube service <serviceName> solved this issue.
For further details look here in minikube docs.
I installed Kubernetes in virtual BOX previously it was working properly but not it is showing The connection to the server 192.168.42.141:6443 was refused - did you specify the right host or port?, Please help.
The connection to the server 192.168.42.141:6443 was refused - did you specify the right host or port?
According to issue there might be kube-apiserver not running state. To check the apiserver status run following command
$ docker ps
# If above is not sowing apiserver container, then it is stopped, To see the stopped container run
$ docker ps -a
P.S: From the comment there is also a version mismatch. To update kubectl follow this
kubectl on any machine reads the current context from kubeconfig file. The file is located at the path $USER_HOME/.kube/config
There are clusters configured inside this file alongwith the IP or domain name of the cluster. If the IP is invalid or not reachable OR the domain name can not be resolved and is unreachable OR the config file is corrupted or the config file is empty, then this error occurs.
In brief, you need to check your config file. It will save you a lot of effort.
How to ssh to the node inside the cluster in local. I am using docker edge version which has kubernetes inbuilt. If i run
kubectl ssh node
I am getting
Error: unknown command "ssh" for "kubectl"
Did you mean this?
set
Run 'kubectl --help' for usage.
error: unknown command "ssh" for "kubectl"
Did you mean this?
set
There is no "ssh" command in kubectl yet, but there are plenty of options to access Kubernetes node shell.
In case you are using cloud provider, you are able to connect to nodes directly from instances management interface.
For example, in GCP: Select Menu -> Compute Engine -> VM instances, then press SSH button on the left side of the desired node instance.
In case of using local VM (VMWare, Virtualbox), you can configure sshd before rolling out Kubernetes cluster, or use VM console, which is available from management GUI.
Vagrant provides its own command to access VMs - vagrant ssh
In case of using minikube, there is minikube ssh command to connect to minikube VM. There are also other options.
I found no simple way to access docker-for-desktop VM, but you can easily switch to minikube for experimenting with node settings.
How to ssh to the node inside the cluster in local
Kubernetes is aware of nodes on level of secure communication with kubelets on nodes (geting hostname and ip from node), and as such, does not provide cluster-level ssh to nodes out of the box. Depending on your actual provide/setup there are different ways of connecting to nodes and they all boil down to locate your ssh key, open appropriate ports on firewall/security groups and issue ssh -i key user#node_instance_ip command to access node. If you are running locally with virtual machines you can setup your own ssh keypairs and do the trick..
You can effectively shell into a pod using exec(I know its not exactly what the question asks, but might be helpful).
An example usage would be kubectl exec -it name-of-your-pod -- /bin/bash. assuming you have bash installed.
Hope that helps.
You have to first Extend kubectl with plugins adding https://github.com/luksa/kubectl-plugins.
Basically, to "install" ssh, e.g.:
wget https://raw.githubusercontent.com/luksa/kubectl-plugins/master/kubectl-ssh
Then make sure the file is in kubectl-ssh your path.
When I define multiple containers in a pod/pod template like one container running agent and another php-fpm, how can they access each other? I need the agent container to connect to php-fpm by shell and need to execute few steps interactively through agent container.
Based on my understanding, we can package kubectl into the agent container and use kubectl exec -it <container id> sh to connect to the container. But I don't want Agent container to have more privilege than to connect to the target container with is php-fpm.
Is there a better way for agent container to connect to php-fpm by a shell and execute commands interactively?
Also, I wasn't successful in running kubectl from a container when using minikube due to following errors
docker run -it -v ~/.kube:/root/.kube lachlanevenson/k8s-kubectl get nodes
Error in configuration:
* unable to read client-cert /Users/user/.minikube/apiserver.crt for minikube due to open /Users/user/.minikube/apiserver.crt: no such file or directory
* unable to read client-key /Users/user/.minikube/apiserver.key for minikube due to open /Users/user/.minikube/apiserver.key: no such file or directory
* unable to read certificate-authority /Users/user/.minikube/ca.crt for minikube due to open /Users/user/.minikube/ca.crt: no such file or directory
docker run -it -v ~/.kube:/root/.kube lachlanevenson/k8s-kubectl get nodes
First off, every Pod within a k8s cluster has its own k8s credentials provided by /var/run/secrets/kubernetes.io/serviceaccount/token, and thus there is absolutely no need to attempt to volume mount your home directory into a docker container
The reason you are getting the error about client-cert is because the contents of ~/.kube are merely strings that point to the externally defined ssl key, ssl certificate, and ssl CA certificate defined inside ~/.kube/config -- but I won't speak to fixing that problem further since there is no good reason to be using that approach