Amazon EKS: generate/update kubeconfig via python script

Question

When using Amazon's K8s offering, the EKS service, at some point you need to connect the Kubernetes API and configuration to the infrastructure established within AWS. Especially we need a kubeconfig with proper credentials and URLs to connect to the k8s control plane provided by EKS.

The Amazon commandline tool aws provides a routine for this task

aws eks update-kubeconfig --kubeconfig /path/to/kubecfg.yaml --name <EKS-cluster-name>

Question: do the same through Python/boto3

When looking at the Boto API documentation, I seem to be unable to spot the equivalent for the above mentioned aws routine. Maybe I am looking at the wrong place.

• is there a ready-made function in boto to achieve this?
• otherwise how would you approach this directly within python (other than calling out to aws in a subprocess)?

Answer 1

There isn't a method function to do this, but you can build the configuration file yourself like this:

# Set up the client
s = boto3.Session(region_name=region)
eks = s.client("eks")

# get cluster details
cluster = eks.describe_cluster(name=cluster_name)
cluster_cert = cluster["cluster"]["certificateAuthority"]["data"]
cluster_ep = cluster["cluster"]["endpoint"]

# build the cluster config hash
cluster_config = {
        "apiVersion": "v1",
        "kind": "Config",
        "clusters": [
            {
                "cluster": {
                    "server": str(cluster_ep),
                    "certificate-authority-data": str(cluster_cert)
                },
                "name": "kubernetes"
            }
        ],
        "contexts": [
            {
                "context": {
                    "cluster": "kubernetes",
                    "user": "aws"
                },
                "name": "aws"
            }
        ],
        "current-context": "aws",
        "preferences": {},
        "users": [
            {
                "name": "aws",
                "user": {
                    "exec": {
                        "apiVersion": "client.authentication.k8s.io/v1alpha1",
                        "command": "heptio-authenticator-aws",
                        "args": [
                            "token", "-i", cluster_name
                        ]
                    }
                }
            }
        ]
    }

# Write in YAML.
config_text=yaml.dump(cluster_config, default_flow_style=False)
open(config_file, "w").write(config_text)