Kubernetes

Aka k8s.

k3s

k3s is a lighter-weight implementation of k8s that runs in a single binary with a smaller memory footprint. You can run this (barely) with 1GB of ram but you probably want at least 2GB + swap.

Install

curl -sfL https://get.k3s.io | sh -

Commands

# Get a list of pods:
kubectl -n <NAMESPACE> get pods

# Edit the deployment config of a deployment (defaults to vim)
kubectl -n <NAMESPACE> edit deploy <DEPLOYMENT NAME>

# Edit the service config of a deployment (defaults to vim)
kubectl -n <NAMESPACE> edit svc <DEPLOYMENT NAME>

# Display the deployment logs
kubectl -n <NAMESPACE> logs deploy/<DEPLOYMENT NAME>

# Get the service config for a deployment
kubectl -n <NAMESPACE> get svc <DEPLOYMENT NAME> -o yaml

# Perform a rolling restart on a config.
kubectl rollout restart deploy <DEPLOYMENT NAME>

# Patch a deployment config (cli alternative to editing)
kubectl -n <NAMESPACE> patch deployment <DEPLOYMENT NAME> --type='json' -p='[{"op": "add", "path": "/spec/template/spec/containers/0/args", "value":["--address", "0.0.0.0:8080"]}]'

# Forward a port locally.
kubectl port-forward -n <NAMESPACE> svc/<DEPLOYMENT NAME> 8080:8080 &

# Scale a deployment to 0 (i.e. disable it)
kubectl scale deployment -n <NAMESPACE> <DEPLOYMENT NAME> --replicas=0

# Get the details of a pod.
kubectl describe pod -n <NAMESPACE> <POD NAME>

# View k8s config:
kubectl config view --raw

# Delete pod:
kubectl delete pod -n <NAMESPACE> -l app=<APP>

OpenFaas

https://docs.openfaas.com/

Install

# Install arkade (pre-req)
curl -sLS https://get.arkade.dev | sh

# Write the config from k3s to where kubernetes would put it.
kubectl config view --raw > ~/.kube/config

# Install OpenFaas to the k3s instance.
arkade install openfaas

# Install the CLI
curl -sSL https://cli.openfaas.com | sudo sh

Get Service Password

PASSWORD=$(kubectl get secret -n openfaas basic-auth -o jsonpath="{.data.basic-auth-password}" | base64 --decode; echo)

Lower Memory

You can reduce memory usage by disabling prometheus and alertmanager:

kubectl scale deployment alertmanager -n openfaas --replicas=0
kubectl scale deployment prometheus -n openfaas --replicas=0

Exposing 8080

Expose the port in the deployment:

kubectl -n openfaas edit deploy gateway

spec:
  template:
    spec:
      containers:
      - args:
        ports:
        - containerPort: 8080
          hostPort: 8080 # Add this line
          name: http
          protocol: TCP

Change the type to NodePort (instead of ClsuterPort):

kubectl -n openfaas edit svc gateway

spec:
  type: NodePort # Change this to "NodePort"

References

• https://midnightprogrammer.net/post/installing-openfaas-on-k3s-single-node/