'Unable to connect to the server: dial tcp: lookup <Server Location>: no such host

I'm beginning to build out a kubernetes cluster for our applications. We are using Azure for cloud services, so my K8s cluster is built using AKS. The AKs cluster was created using the portal interface for Azure. It has one node, and I am attempting to create a pod with a single container to deploy to the node. Where I am stuck currently is trying to connect to the AKS cluster from Powershell. The steps I have taken are:

az login (followed by logging in)
az account set --subscription <subscription id>
az aks get-credentials --name <cluster name> --resource-group <resource group name>
kubectl get nodes

After entering the last line, I am left with the error: Unable to connect to the server: dial tcp: lookup : no such host

I've also gone down a few other rabbit holes found on SO and other forums, but quite honestly, I'm looking for a straight forward way to access my cluster before complicating it further.

Edit: So in the end, I deleted the resource I was working with and spun up a new version of AKS, and am now having no trouble connecting. Thanks for the suggestions though!

Solution 1:^[1]

As of now, the aks run command adds a fourth option to connect to private clusters extending @Darius's three options posted earlier:

Use the AKS Run Command feature.

az aks command invoke -g <resourceGroup> -n <clusterName> -c "kubectl get pods -n kube-system"
az aks command invoke -g <resourceGroup> -n <clusterName> -c "kubectl get nodes"

In case you get a (ResourceGroupNotFound) error, try adding the subscription, too

az aks command invoke -g <resourceGroup> -n <clusterName> --subscription <subscription> -c "kubectl get nodes"

You can also configure the default subscription:

az account set -s <subscription>

Solution 2:^[2]

Unable to connect to the server: dial tcp: lookup : no such host

The error is coming because of private cluster. The Private Cluster option is enabled while creating the AKS cluster. You need to disable this option.

Kubectl is a kubernetes control client. It is an external connectivity provider to connect with our kubernetes cluster. We can't connect with the private cluster externally.

Believe me.... just disable the private cluster options And see your success. Thank you.

Note: We can't disable this option after the cluster creation. you need to delete the cluster and again reform it.

Solution 3:^[3]

Posting this as Community Wiki for better visibility.

Solution provided by OP:

Delete resource and spun up a new version of AKS.

For details, you can check docs Create a resource group, Create AKS cluster and resource create.

Next try worth to try:

kubectl config use-context <cluster-name>

as it was proposed in similar Github issue.

Solution 4:^[4]

Gaurav's answer pretty much sums it up. In fact you can refer to the documentation which states that

The API server endpoint has no public IP address. To manage the API server, you'll need to use a VM that has access to the AKS cluster's Azure Virtual Network (VNet). There are several options for establishing network connectivity to the private cluster.

To connect to a private cluster, there are only 3 methods:

Create a VM in the same Azure Virtual Network (VNet) as the AKS cluster.

Use a VM in a separate network and set up Virtual network peering. See the section below for more information on this option.

Use an Express Route or VPN connection.

Solution 5:^[5]

It is more convenient to use Az module from desktop Powershell for any management operation with Azure portal. Microsoft adds a lot of new cmdlets for managing AKS and Service Fabric clusters.

Please take a look Az.Aks

In your case:

Connect-AzAccount

Get-AzAksNodePool

Solution 6:^[6]

I was also facing the issue, I'm using a private cluster and I have a machine (bastion) in a different vnet with peering enabled but still, I was not able to connect the cluster (I was able to SSH and telnet to the machine).

Then I added a virtual network link in the private DNS zone for the vnet where the bastion host resides. It worked for me, I'm able to access the cluster.

Solution 7:^[7]

When using a private cluster, the kubernetes api-endpoint is only accessible on the cluster's VNet. Connecting via VPN unfortunately does not work painlessly since the azure private DNS will not be available via for VPN clients (yet).

However, it is possible to connect kubectl directly to the IP-address of the api-endpoint, but that will require you to ignore certificate errors since we are using the IP directly.

If you edit your .kube/config and change the server address to the IP number. Then call kubectl with something like this

kubectl get all --all-namespaces --insecure-skip-tls-verify

Solution 8:^[8]

Usually, this is all that is required to connect. Check whether firewall is not blocking any traffic. Also, verify subscription id and other identifiers again and make sure you are using the correct values. If the issue still persists, I recommend you ask azure support to help you out.

Solution 9:^[9]

I had the same issues when running the kubectl command from jenkins. For me it was the permission issues of ~/.kube/config I gave it access to jenkins as well which solved the issue for me.

Solution 10:^[10]

You can run kubectl commands on a private AKS cluster using az aks command invoke. Refer to this for more info.

As for why you might want to run private AKS clusters, read this

Solution 11:^[11]

For me I had this issue when I was trying to connect a new Linux user to my Elastic Kubernetes Cluster in AWS.

I setup a new user called jenkins-user, then I tried to run the command below to get pods:

kubectl get pods

And then I will run into the error below:

Unable to connect to the server: dial tcp: lookup 23343445ADFEHGROGMFDFMG.sk1.eu-east-2.eks.amazonaws.com on 198.74.83.506:53: no such host

Here's how I solved it:

The issue was because I had not set the context for the Kubernetes cluster in the kube config file of the new linux user (jenkins-user).

All I had to do was either first install the aws-cli for this new user (install it into the home directory of this new user). And then run the command aws configure to configure the necessary credentials. Although, since I already had the aws-cli setup for the other users on the linux system I simply copied the ~/.aws directory from an already existing user to the jenkins-user home directory using the command:

sudo cp -R /home/existing-user/.aws/ /home/jenkins-user/

Next, I had to create a context for the kubernetes configuration which will create a new ~/.kube/config file for the jenkins-user using the command below:

aws eks --region my-aws-region update-kubeconfig --name my-cluster-name

Next, I checked the kube config file to confirm that my context has been added using the command:

sudo nano /.kube/config

This time when I ran the command below, it was successful:

kubectl get pods

Resources: Create a kubeconfig for Amazon EKS

That's all

Solution 12:^[12]

You can simply append "--admin" to the query as seen below.

az aks get-credentials --name <cluster name> --resource-group <resource group name> --admin

Solution 13:^[13]

I also hit this after restarting my kubernetes cluster, but it turned out I was just not waiting long enough, after about 10 minutes the "kubectrl" commands started working again.

Solution 14:^[14]

If you are using AWS with kops then this might help you

mkdir autoscaler
cd autoscaler/
git clone https://github.com/kubernetes/autoscaler.git

create a file called ig-policy.json with the contents

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "autoscaling:DescribeAutoScalingGroups",
                "autoscaling:DescribeAutoScalingInstances",
                "autoscaling:DescribeLaunchConfigurations",
                "autoscaling:SetDesiredCapacity",
                "autoscaling:TerminateInstanceInAutoScalingGroup"
            ],
            "Resource": "*"
        }
    ]
}

Then you need to create iam policy

aws iam create-policy --policy-name ig-policy --policy-document file://ig-policy.json

And attach the above create iam policy with the user id to the cluster name

aws iam attach-role-policy --policy-arn arn:aws:iam::005935423478650:policy/ig-policy --role-name nodes.testing.k8s.local

Then update the cluster

kops update cluster testing.k8s.local --yes

Then run

kops rolling-update cluster

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution	Source
Solution 1	Carambakaracho
Solution 2	Gaurav Gupta
Solution 3
Solution 4	Darius
Solution 5	Oleh Tarasenko
Solution 6	harsha
Solution 7	Martin S
Solution 8	Saurabh Nigam
Solution 9	Tara Prasad Gurung
Solution 10	Ilhaan Rasheed
Solution 11
Solution 12	Harsh Manvar
Solution 13	Chris
Solution 14	yogesh cl

'Unable to connect to the server: dial tcp: lookup <Server Location>: no such host

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