How to make a kubernetes cups server on a raspberry pi 3 using k3s.

a-howto.md

Introduction

• Me: I want a kubernetes cluster for my nefarious purposes, but I'm a cheapskate who doesnt want to spend money on a DO droplet.
• Also Me: LOOK! A raspberry pi 3 I'm not using. But wait, it's too small for a k8s cluster.

That's when I decided I wanted a k3s master. It seems a raspberry pi 3 is exactly what I needed.

Requiments

• Raspberry Pi 3B
• raspbian (or the artist formerly known as raspbian) raspberry pi os?
• A static IP. On my router I set up a static ip for my raspberry pi. Thought this might make discovery and kubectl happier if it was always an ip I could count on.

Node Setup

On the router set the raspberry pi's ip to something known. I made mine 192.168.8.200 because that's in the CIDR range used by my router. Makes ssh easier also ie:

ssh pi@192.168.8.200
# raspberry

Install raspberry pi os here

ON THE PI: Disable swap (just like a real kubernetes). On a raspberry pi os, this means:

sudo dphys-swapfile swapoff
sudo systemctl disable dphys-swapfile.service

ON THE PI: Install k3s as per the website:

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

ON THE PI: make the kubeconfig available for copy via scp:

cp /etc/rancher/k3s/k3s.yaml  /home/pi

From your laptop copy the kubeconfig:

scp pi@192.168.8.200:k3s.yaml .
export KUBECONFIG=$PWD/k3s.yaml
sed -i 's/127.0.0.1/192.168.8.200/' k3s.yaml   # or whatever IP you selected for the rpi
kubectl get po -A

Congrats, That should be enough for a single node k3s master

b-add-cups.md

Adding cups to your k3s raspberry pi server

Requirements:

• Cross building of docker images requires buildx

steps:

• setup the infrastructure:

 { 
   docker run --rm --privileged multiarch/qemu-user-static --reset -p yes;
   docker buildx rm builder;
   docker buildx create --name builder --driver docker-container --use;
   docker buildx inspect --bootstrap; 
 }

• Build your docker using buildx:

 docker buildx build --platform linux/arm/v7 -t cups:stephan2 . --output type=docker,dest=- > container-data.tar 

• copy container-data.tar to the raspberry pi and import:

k3s ctr i  import container-data.tar

• apply all the yaml on the new cluster:

kubectl apply -f configmap.yaml # see the other files in this gist
kubectl apply -f cups-deployment-and-service.yaml

Note that this is a privileged pod, and that it requires to mount the dbus and dev directories.

Then you can navigate to your raspberrypi-ip:31631 (I changed the default port of the cups server from 631)

Set up your printer from there. If it worked you printer should be visible in the Administration --> Add a printer view.

configmap.yaml

apiVersion: v1
data:
  cupsd.conf: "#\n#\n# Sample configuration file for the CUPS scheduler.  See \"man
    cupsd.conf\" for a\n# complete description of this file.\n#\n\n# Log general information
    in error_log - change \"warn\" to \"debug\"\n# for troubleshooting...\nLogLevel
    debug2\n\n# Deactivate CUPS' internal logrotating, as we provide a better one,
    especially\n# LogLevel debug2 gets usable now\nMaxLogSize 0\n\n# Listen to all\nPort
    31631\nListen /var/run/cups/cups.sock\nListen 127.0.0.1:31631 \n\n# Show shared
    printers on the local network.\nBrowsing On\nBrowseLocalProtocols dnssd\n\n# Default
    authentication type, when authentication is required...\nDefaultAuthType Basic\nDefaultEncryption
    IfRequested\n\n# Web interface setting...\nWebInterface Yes\n\n# Restrict access
    to the server...\n<Location />\n  Order allow,deny\n  Allow all\n</Location>\n\n#
    Restrict access to the admin pages...\n<Location /admin>\n  Order allow,deny\n
    \ Allow all\n</Location>\n\n# Restrict access to configuration files...\n<Location
    /admin/conf>\n  AuthType Default\n  Require user @SYSTEM\n  Order allow,deny\n
    \ Allow all\n</Location>\n\n# Set the default printer/job policies...\n<Policy
    default>\n  # Job/subscription privacy...\n  JobPrivateAccess default\n  JobPrivateValues
    default\n  SubscriptionPrivateAccess default\n  SubscriptionPrivateValues default\n\n
    \ # Job-related operations must be done by the owner or an administrator...\n
    \ <Limit Create-Job Print-Job Print-URI Validate-Job>\n    Order deny,allow\n
    \ </Limit>\n\n  <Limit Send-Document Send-URI Hold-Job Release-Job Restart-Job
    Purge-Jobs Set-Job-Attributes Create-Job-Subscription Renew-Subscription Cancel-Subscription
    Get-Notifications Reprocess-Job Cancel-Current-Job Suspend-Current-Job Resume-Job
    Cancel-My-Jobs Close-Job CUPS-Move-Job CUPS-Get-Document>\n    Require user @OWNER
    @SYSTEM\n    Order deny,allow\n  </Limit>\n\n  # All administration operations
    require an administrator to authenticate...\n  <Limit CUPS-Add-Modify-Printer
    CUPS-Delete-Printer CUPS-Add-Modify-Class CUPS-Delete-Class CUPS-Set-Default CUPS-Get-Devices>\n
    \   AuthType Default\n    Require user @SYSTEM\n    Order deny,allow\n  </Limit>\n\n
    \ # All printer operations require a printer operator to authenticate...\n  <Limit
    Pause-Printer Resume-Printer Enable-Printer Disable-Printer Pause-Printer-After-Current-Job
    Hold-New-Jobs Release-Held-New-Jobs Deactivate-Printer Activate-Printer Restart-Printer
    Shutdown-Printer Startup-Printer Promote-Job Schedule-Job-After Cancel-Jobs CUPS-Accept-Jobs
    CUPS-Reject-Jobs>\n    AuthType Default\n    Require user @SYSTEM\n    Order deny,allow\n
    \ </Limit>\n\n  # Only the owner or an administrator can cancel or authenticate
    a job...\n  <Limit Cancel-Job CUPS-Authenticate-Job>\n    Require user @OWNER
    @SYSTEM\n    Order deny,allow\n  </Limit>\n\n  <Limit All>\n    Order deny,allow\n
    \ </Limit>\n</Policy>\n\n# Set the authenticated printer/job policies...\n<Policy
    authenticated>\n  # Job/subscription privacy...\n  JobPrivateAccess default\n
    \ JobPrivateValues default\n  SubscriptionPrivateAccess default\n  SubscriptionPrivateValues
    default\n\n  # Job-related operations must be done by the owner or an administrator...\n
    \ <Limit Create-Job Print-Job Print-URI Validate-Job>\n    AuthType Default\n
    \   Order deny,allow\n  </Limit>\n\n  <Limit Send-Document Send-URI Hold-Job Release-Job
    Restart-Job Purge-Jobs Set-Job-Attributes Create-Job-Subscription Renew-Subscription
    Cancel-Subscription Get-Notifications Reprocess-Job Cancel-Current-Job Suspend-Current-Job
    Resume-Job Cancel-My-Jobs Close-Job CUPS-Move-Job CUPS-Get-Document>\n    AuthType
    Default\n    Require user @OWNER @SYSTEM\n    Order deny,allow\n  </Limit>\n\n
    \ # All administration operations require an administrator to authenticate...\n
    \ <Limit CUPS-Add-Modify-Printer CUPS-Delete-Printer CUPS-Add-Modify-Class CUPS-Delete-Class
    CUPS-Set-Default>\n    AuthType Default\n    Require user @SYSTEM\n    Order deny,allow\n
    \ </Limit>\n\n  # All printer operations require a printer operator to authenticate...\n
    \ <Limit Pause-Printer Resume-Printer Enable-Printer Disable-Printer Pause-Printer-After-Current-Job
    Hold-New-Jobs Release-Held-New-Jobs Deactivate-Printer Activate-Printer Restart-Printer
    Shutdown-Printer Startup-Printer Promote-Job Schedule-Job-After Cancel-Jobs CUPS-Accept-Jobs
    CUPS-Reject-Jobs>\n    AuthType Default\n    Require user @SYSTEM\n    Order deny,allow\n
    \ </Limit>\n\n  # Only the owner or an administrator can cancel or authenticate
    a job...\n  <Limit Cancel-Job CUPS-Authenticate-Job>\n    AuthType Default\n    Require
    user @OWNER @SYSTEM\n    Order deny,allow\n  </Limit>\n\n  <Limit All>\n    Order
    deny,allow\n  </Limit>\n</Policy>\n\n#\n#\n"
kind: ConfigMap
metadata:
  name: cupsd-conf
  namespace: default

cups-deployment-and-service.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: cups
  name: cups
  namespace: default
spec:
  replicas: 1
  selector:
    matchLabels:
      app: cups
  strategy:
    rollingUpdate:
      maxSurge: 25%
      maxUnavailable: 25%
    type: RollingUpdate
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: cups
    spec:
      containers:
      - image: cups:stephan2
        imagePullPolicy: IfNotPresent
        name: cups
        resources: {}
        securityContext:
          privileged: true
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
        volumeMounts:
        - mountPath: /etc/cups/ppd/
          name: printy-ppd
        - mountPath: /etc/cups/
          name: cupsd-conf
        - mountPath: /var/run/dbus
          name: dbus-host-vol
        - mountPath: /dev/bus/usb
          name: usb-host-vol
      dnsPolicy: ClusterFirst
      hostIPC: true
      hostNetwork: true
      hostPID: true
      restartPolicy: Always
      schedulerName: default-scheduler
      securityContext: {}
      terminationGracePeriodSeconds: 30
      volumes:
      - configMap:
          defaultMode: 420
          items:
          - key: cupsd.conf
            path: cupsd.conf
          name: cupsd-conf
        name: cupsd-conf
      - hostPath:
          path: /tmp/printyppd
          type: ""
        name: printy-ppd
      - hostPath:
          path: /var/run/dbus
          type: ""
        name: dbus-host-vol
      - hostPath:
          path: /dev/bus/usb
          type: ""
        name: usb-host-vol
---
apiVersion: v1
kind: Service
metadata:
  labels:
    app: cups
  name: cups
  namespace: default
  selfLink: /api/v1/namespaces/default/services/cups
spec:
  clusterIP: 10.43.105.64
  externalTrafficPolicy: Cluster
  ports:
  - nodePort: 31631
    port: 31631
    protocol: TCP
    targetPort: 31631
  selector:
    app: cups
  sessionAffinity: None
  type: NodePort
status:
  loadBalancer: {}

Dockerfile

# stole this basically from `https://github.com/lemariva/wifi-cups-server`
# creates a docker image `cups:stephan2`

FROM debian:buster

ARG TARGETPLATFORM
ARG BUILDPLATFORM
RUN echo "I am running on $BUILDPLATFORM, building for $TARGETPLATFORM" 

RUN apt-get update && apt-get install -y \
  sudo \
  locales \
  whois \
  cups \
  cups-client \
  cups-bsd \
  printer-driver-all \
  printer-driver-gutenprint \
  hpijs-ppds \
  hp-ppd  \
  hplip \
  printer-driver-foo2zjs

ENV LANG=en_US.UTF-8 \
  LC_ALL=en_US.UTF-8 \
  LANGUAGE=en_US:en

RUN useradd \
  --groups=sudo,lp,lpadmin \
  --create-home \
  --home-dir=/home/print \
  --shell=/bin/bash \
  --password=$(mkpasswd print) \
  print \
  && sed -i '/%sudo[[:space:]]/ s/ALL[[:space:]]*$/NOPASSWD:ALL/' /etc/sudoers \
  && apt-get clean \
  && rm -rf /var/lib/apt/lists/* \
  && mkdir /var/lib/apt/lists/partial

# Might not be necessary since we are using configmaps now.
# alternatively make a `etc-cups` directory with a default `cupsd.conf`
# COPY etc-cups/cupsd.conf /etc/cups/cupsd.conf

EXPOSE 631

ENTRYPOINT ["/usr/sbin/cupsd", "-f"]

Note I deviate from the original Dockerfile in using a configmap. I did however make the image with a default configmap originally just like
https://github.com/lemariva/wifi-cups-server did, but am now overriding it.

Tabs can not be encoded properly in yaml. If you get rid of \t you can make your Configmap human-readable

Hello @svanellewee , thank you for posting your code. I tried working with your code on Openshift locally on my laptop. I had to make some modifications to the yaml and the cupsd.conf to get it deployed. After deployment i'm facing two issues.

1. logs do not show up anywhere for the pods
2. while trying to add a printer, every time I click on add a printer, I get the following error "Request Entity Too Large" .
   Do you have any idea how to fix these?
   The modified files are here https://github.com/sayantandas/cups-ocp