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Offline Microk8s installation issues

See install alternatives for offline installation of Microk8s, but there are additional steps to install microk8s offline. See the following steps to install offline:

Importing images

After running the following:

snap ack microk8s_{microk8s_version}.assert
snap install microk8s_{microk8s_version}.snap --classic

You should check if the microk8s instance is healthy. Do it using the following command:

microk8s kubectl get pods -A

The output will probably look like:

NAMESPACE      NAME                                       READY   STATUS     RESTARTS   AGE
kube-system    calico-kube-controllers-7c9c8dd885-fg8f2   0/1     Pending    0          14m
kube-system    calico-node-zg4c4                          0/1     Init:0/3   0          23s

The pods are in the Pending/Init state because they’re trying to download images, which is impossible to do offline. In order to make them download, you need to download all the images on a different server with an internet connection, pack it up, and import it to a microk8s image registry on your offline server.

Packing up images for an offline environment

You need to monitor

microk8s kubectl get events -A

to see if microk8s fails to pull images, and then import anything it needs. An example of such information is:

kube-system    0s          Warning   Failed              pod/calico-node-sc784                           Failed to pull image "docker.io/calico/cni:v3.21.4": rpc error: code = Unknown desc = failed to pull and unpack image "docker.io/calico/cni:v3.21.4": failed to resolve reference "docker.io/calico/cni:v3.21.4": failed to do request: Head "https://registry-1.docker.io/v2/calico/cni/manifests/v3.21.4": dial tcp 54.83.42.45:443: i/o timeout
kube-system    0s          Warning   Failed              pod/calico-node-sc784                           Error: ErrImagePull

The previous information shows you that you lack a docker.io/calico/cni:v3.21.4 image, and need to import it in order to fix the issue.

The process to do this action is always the following:

docker pull <needed_image>
docker save <needed_image> > image.tar

Transfer package to the offline lab and execute:

microk8s ctr image import image.tar

Example of the offline installation

For example, microk8s version 3597 requires the following images to work correctly:

docker pull docker.io/calico/kube-controllers:v3.21.4 
docker pull docker.io/calico/node:v3.21.4
docker pull docker.io/calico/pod2daemon-flexvol:v3.21.4
docker pull docker.io/calico/cni:v3.21.4  
docker pull k8s.gcr.io/pause:3.1 
docker pull k8s.gcr.io/metrics-server/metrics-server:v0.5.2

You should issue the above commands on your instance connected to the internet, then save it to tar packages:

docker save docker.io/calico/kube-controllers:v3.21.4 > kube-controllers.tar
docker save docker.io/calico/node:v3.21.4 > node.tar
docker save docker.io/calico/pod2daemon-flexvol:v3.21.4 > pod2daemon-flexvol.tar
docker save docker.io/calico/cni:v3.21.4 > cni.tar
docker save k8s.gcr.io/pause:3.1  > pause.tar
docker save cdkbot/hostpath-provisioner:1.2.0 > cdkbot.tar 
docker save k8s.gcr.io/metrics-server/metrics-server:v0.5.2 > metrics.tar

After that, scp those packages to your offline server and import it to its microk8s image registry:

microk8s ctr image import kube-controllers.tar
microk8s ctr image import node.tar
microk8s ctr image import pod2daemon-flexvol.tar
microk8s ctr image import cni.tar
microk8s ctr image import pause.tar
microk8s ctr image import metrics.tar

NOTE: for other versions of microk8s, tags of images may differ.

After running the following:

microk8s enable hostpath-storage
microk8s enable rbac
microk8s enable metrics-server

The microk8s instance should be the following:

NAMESPACE      NAME                                       READY   STATUS                  RESTARTS   AGE
kube-system    calico-kube-controllers-7c9c8dd885-wxms9   1/1     Running                 0          3h21m
kube-system    calico-node-8cxsq                          1/1     Running                 0          3h21m
kube-system    hostpath-provisioner-f57964d5f-zs4sj       1/1     Running                 0          5m41s
kube-system    metrics-server-5f8f64cb86-x7k29            1/1     Running                 0          2m15s

Enabling DNS and Metallb

dns and metallb don’t require importing any images, so you can enable them simply through the following commands:

microk8s enable dns
microk8s enable metallb

For more information on metallb, see Install metallb.

Installing helm3

Additionally, you need to install the helm3 add-on. See the following steps:

  1. Check your server’s platform with:
dpkg --print-architecture

The output would be, for example: amd64. You need the platform to download the correct version of helm.

  1. Download the helm package from https://get.helm.sh/helm-v3.8.0-linux-{{arch}}.tar.gz, where {{arch}} should be replaced with the result from the previous command, for example: https://get.helm.sh/helm-v3.8.0-linux-amd64.tar.gz.

  2. Rename the package to helm.tar.gz and send it to an offline lab.

  3. Create tmp directory in /var/snap/microk8s/current and copy the package in the following locations: 
sudo mkdir -p /var/snap/microk8s/current/tmp/helm3
sudo cp helm.tar.gz /var/snap/microk8s/current/tmp/helm3
  1. Go to the directory containing enable script for helm3:
cd /var/snap/microk8s/common/addons/core/addons/helm3

Open enable file with vi, nano, or some other editor. Comment this line:

#fetch_as $SOURCE_URI/helm-$HELM_VERSION-linux-${SNAP_ARCH}.tar.gz "$SNAP_DATA/tmp/helm3/helm.tar.gz"

Save file.

  1. Run microk8s enable helm3

Verify your instance

Check if all the add-ons were installed successfully using the following command: microk8s status --wait-ready. An example of a correct output is:

microk8s is running
high-availability: no
  datastore master nodes: 127.0.0.1:19001
  datastore standby nodes: none
addons:
  enabled:
    dns                  # (core) CoreDNS
    ha-cluster           # (core) Configure high availability on the current node
    helm3                # (core) Helm 3 - Kubernetes package manager
    hostpath-storage     # (core) Storage class; allocates storage from host directory
    metallb              # (core) Loadbalancer for your Kubernetes cluster
    metrics-server       # (core) K8s Metrics Server for API access to service metrics
    rbac                 # (core) Role-Based Access Control for authorisation
    storage              # (core) Alias to hostpath-storage add-on, deprecated
  disabled:
    community            # (core) The community addons repository
    dashboard            # (core) The Kubernetes dashboard
    gpu                  # (core) Automatic enablement of Nvidia CUDA
    helm                 # (core) Helm 2 - the package manager for Kubernetes
    host-access          # (core) Allow Pods connecting to Host services smoothly
    ingress              # (core) Ingress controller for external access
    mayastor             # (core) OpenEBS MayaStor
    prometheus           # (core) Prometheus operator for monitoring and logging
    registry             # (core) Private image registry exposed on localhost:32000