Kubernetes Connectivity Checker

Kubernetes Connectivity Checker was created for .. checking http(s) connnectivity in Kubernetes environments with several admin network policies, network policies, and baseline admin network policies defined.

Some parameters of checks such as target url, check interval, accepted status code, proxy can be configured.

The check result is made available in a status page /status on port 8080 in form of simple OK, NOK message, while more information can be found in the STDOUT log.

This program should work with 2 other programs (which are outside of this repo):

• provisioning of k8s connectivity checkers on a Kubernetes cluster
• visualization dashboard of k8s connectivity checker results

Build

Code can be used direcly or inside a Docker container. To create a Docker image, run:

docker build -t k8s-connectivity-checker .

Configuration

Program is configured using environment variables:

Variable	Required	Description	Default
TARGET_URL	yes	HTTP(s) endpoint to check	-
CHECK_INTERVAL	no	Interval between checks	60s
ACCEPTED_STATUS_CODES	no	When defined, check is marked as successful only if returned http status code is included in this parameter	200
HTTP_PROXY	no	Proxy address to use for http checks	-
HTTPS_PROXY	no	Proxy address to use for https checks	-

Usage

While the program was created with the specific need of checking K8s connectivity, it can be used outside of the Kubernetes ecosystem.

Direct usage

Program can be executed directly using Python virtual environment.

Environment preparation

When running the program directly using Python, a virtual environment has to be created, and dependencies installed:

python3 -m venv venv
source venv/bin/activate
python3 -m pip install -r requirements.txt

Python execution

Supply parameters using environment variables, e.g.:

TARGET_URL=https://example.com python3 app.py

Docker container

Build image

For instructions on how to build checker docker image see Build

Docker container execution

docker run -e TARGET_URL=https://example.com k8s-connectivity-checker

Build image and push to registry

For instructions on how to build checker docker image see Build

Image has to be available for the Kubernetes cluster => push to a OCI registry:

docker push <registry_url>/k8s-connectivity-checker:latest

Kubernetes cluster

Create a deployment:

kubectl create deployment listener --image="<registry-url>/k8s-connectivity-checker" -n "<namespace>"
kubectl patch deployment listener -n "<namespace>" -p "{\"spec\": {\"template\": {\"spec\": {\"imagePullSecrets\": [{\"name\": \"<secret-with-docker-credentials>\"}], \"containers\": [{\"name\": \"k8s-connectivity-checker\", \"env\": [{\"name\": \"TARGET_URL\", \"value\": \"http://listener:8080/status\"}]}]}}}}"

TODO

• supply k8s manifests
• provisioning / visualisation dashboard