healthcheck-k8s

README

healthcheck-k8s

Check if the specified Kubernetes node is schedulable and return as HTTP status code.

Requirements

• Go
• Kubernetes

Installation

$ docker buildx build .

# Port number (required)
export PORT=8080

# Name of header in which client sends a node name (required)
export HEADER_NAME=X-Node

# Path to the kubeconfig, or else falls back to service account token mounted inside the Pod (optional)
export KUBECONFIG=$HOME/.kube/config

# Timeout in milliseconds (optional; zero means infinity)
export TIMEOUT_MS=30000

# IPv4/IPv6 addresses of trusted proxies in CIDR (optional; comma-separated)
export TRUSTED_PROXIES=10.0.0.0/8,172.16.0.0/12,192.168.0.0/16

Testing

Set up

$ make setup-envtest

Run

$ source <(bin/setup-envtest use latest -p env)
$ go test ./...

Usage

$ ./healthcheck-k8s

Normal: node is schedulable

$ curl --dump-header - -H 'X-Node: minikube' localhost:8080
HTTP/1.1 200 OK
Content-Type: text/plain; charset=utf-8
Date: Wed, 01 Jan 2020 00:00:00 GMT
Content-Length: 26

Node(s) are OK: "minikube"

Cordoned: node is unschedulable

$ kubectl cordon minikube
node/minikube uncordoned

$ curl --dump-header - -H 'X-Node: minikube' localhost:8080
HTTP/1.1 503 Service Unavailable
Content-Type: text/plain; charset=utf-8
Date: Wed, 01 Jan 2020 00:00:00 GMT
Content-Length: 52

Node "minikube" is currently undergoing maintenance.

Spec

Status	Condition
200	Node is schedulable.
400	Header is not present in the request.
404	Node was not found.
500	Unexpected error when retrieving node status.
503	Node is unschedulable.
504	Timed out connecting to kube-apiserver.