Kubernetes in a snap that you can run locally.
Snaps are frequently updated to match each release of Kubernetes. The quickest way to get started is to install directly from the snap store. You can install MicroK8s and let it update to the latest stable upstream Kubernetes release with:
snap install microk8s --classic
Alternatively, you can select a MicroK8s channel that will follow a specific Kubernetes release series. For example, you install MicroK8s and let it follow the v1.12 series with:
snap install microk8s --classic --channel=1.12/stable
You can read more on the MicroK8s release channels in the Release Channels and Upgrades doc.
At any point you can check MicroK8s' availability with:
microk8s.status
During installation you can use the --wait-ready flag to wait for the kubernetes services to initialise:
microk8s.status --wait-ready
In order to install MicroK8s make sure
- you go though the list of ports that need to be available
To avoid colliding with a kubectl already installed and to avoid overwriting any existing Kubernetes configuration file, MicroK8s adds a microk8s.kubectl command, configured to exclusively access the new MicroK8s install. When following instructions online, make sure to prefix kubectl with microk8s..
microk8s.kubectl get nodes
microk8s.kubectl get services
If you do not already have a kubectl installed you can alias microk8s.kubectl to kubectl using the following command
snap alias microk8s.kubectl kubectl
This measure can be safely reverted at anytime by doing
snap unalias kubectl
If you already have kubectl installed and you want to use it to access the MicroK8s deployment you can export the cluster's config with:
microk8s.kubectl config view --raw > $HOME/.kube/config
Note: The API server on port 8080 is listening on all network interfaces. In its kubeconfig file MicroK8s is using the loopback interface, as you can see with microk8s.kubectl config view. The microk8s.config command will output a kubeconfig with the host machine's IP (instead of the 127.0.0.1) as the API server endpoint.
MicroK8s installs a barebones upstream Kubernetes. This means just the api-server, controller-manager, scheduler, kubelet, cni, kube-proxy are installed and run. Additional services like kube-dns and dashboard can be run using the microk8s.enable command
microk8s.enable dns dashboard
These addons can be disabled at anytime using the disable command
microk8s.disable dashboard dns
With microk8s.status you can see the list of available addons and which ones are currently enabled. You can find the addon manifests and/or scripts under ${SNAP}/actions/, with ${SNAP} pointing by default to /snap/microk8s/current.
- dns: Deploy kube dns. This addon may be required by others thus we recommend you always enable it. In environments where the external dns servers
8.8.8.8and8.8.4.4are blocked you will need to update the upstream dns servers inmicrok8s.kubectl -n kube-system edit configmap/kube-dnsafter enabling the addon. - dashboard: Deploy kubernetes dashboard as well as grafana and influxdb. To access grafana point your browser to the url reported by
microk8s.kubectl cluster-info. - storage: Create a default storage class. This storage class makes use of the hostpath-provisioner pointing to a directory on the host. Persistent volumes are created under
${SNAP_COMMON}/default-storage. Upon disabling this addon you will be asked if you want to delete the persistent volumes created. - ingress: Create an ingress controller.
- gpu: Expose GPU(s) to MicroK8s by enabling the nvidia runtime and nvidia-device-plugin-daemonset. Requires NVIDIA drivers to already be installed on the host system.
- istio: Deploy the core Istio services. You can use the
microk8s.istioctlcommand to manage your deployments. - registry: Deploy an image private registry and expose it on
localhost:32000. The storage addon will be enabled as part of this addon. See the registry documentation for more details. - metrics-server: Deploy the Metrics Server.
- prometheus: Deploy the Prometheus Operator v0.25.
- fluentd: Deploy Elasticsearch-Kibana-Fluentd logging and monitoring solution.
- jaeger: Deploy the Jaeger Operator v1.8.2 in the "simplest" configuration.
You may wish to temporarily shutdown MicroK8s when not in use without un-installing it.
MicroK8s can be shutdown with:
microk8s.stop
MicroK8s can be restarted later with:
microk8s.start
Before removing MicroK8s, use microk8s.reset to stop all running pods.
microk8s.reset
snap remove microk8s
The following systemd services will be running in your system:
- snap.microk8s.daemon-apiserver, is the kube-apiserver daemon started using the arguments in
${SNAP_DATA}/args/kube-apiserver - snap.microk8s.daemon-controller-manager, is the kube-controller-manager daemon started using the arguments in
${SNAP_DATA}/args/kube-controller-manager - snap.microk8s.daemon-scheduler, is the kube-scheduler daemon started using the arguments in
${SNAP_DATA}/args/kube-scheduler - snap.microk8s.daemon-kubelet, is the kubelet daemon started using the arguments in
${SNAP_DATA}/args/kubelet - snap.microk8s.daemon-proxy, is the kube-proxy daemon started using the arguments in
${SNAP_DATA}/args/kube-proxy - snap.microk8s.daemon-containerd, is the containerd daemon started using the configuration in
${SNAP_DATA}/args/containerdand${SNAP_DATA}/args/containerd-template.toml. - snap.microk8s.daemon-etcd, is the etcd daemon started using the arguments in
${SNAP_DATA}/args/etcd
Normally, ${SNAP_DATA} points to /var/snap/microk8s/current.
To reconfigure a service you will need to edit the corresponding file and then restart the respective daemon. For example:
echo '-l=debug' | sudo tee -a /var/snap/microk8s/current/args/containerd
sudo systemctl restart snap.microk8s.daemon-containerd.service
To let MicroK8s use a proxy enter the proxy details in ${SNAP_DATA}/args/containerd-env and restart the containerd daemon service with:
sudo systemctl restart snap.microk8s.daemon-containerd.service
To troubleshoot a non-functional MicroK8s deployment, start by running the microk8s.inspect command. This command performs a set of tests against MicroK8s and collects traces and logs in a report tarball. In case any of the aforementioned daemons are failing you will be urged to look at the respective logs with journalctl -u snap.microk8s.<daemon>.service. microk8s.inspect may also make suggestions on potential issues it may find. If you do not manage to resolve the issue you are facing please file a bug attaching the inspection report tarball.
Some common problems and solutions are listed below.
The Kubenet network plugin used by MicroK8s creates a cbr0 interface when the first pod is created. If you have ufw enabled, you'll need to allow traffic on this interface:
sudo ufw allow in on cbr0 && sudo ufw allow out on cbr0
Make sure packets to/from the pod network interface can be forwarded to/from the default interface on the host:
sudo iptables -P FORWARD ACCEPT
or, if using ufw:
sudo ufw default allow routed
The MicroK8s inspect command can be used to check the firewall configuration:
microk8s.inspect
A warning will be shown if the firewall is not forwarding traffic.
By default container logs are located in /var/log/pods/{id}. You have to mount this location in your log collector for that to work. Following is an example diff for fluent-bit:
@@ -36,6 +36,9 @@
- name: varlibdockercontainers
mountPath: /var/lib/docker/containers
readOnly: true
+ - name: varlibdockercontainers
+ mountPath: /var/snap/microk8s/common/var/lib/containerd/
+ readOnly: true
- name: fluent-bit-config
mountPath: /fluent-bit/etc/
terminationGracePeriodSeconds: 10
@@ -45,7 +48,7 @@
path: /var/log
- name: varlibdockercontainers
hostPath:
- path: /var/lib/docker/containers
+ mountPath: /var/snap/microk8s/common/var/lib/containerd/
- name: fluent-bit-config
configMap:
name: fluent-bit-configTo build the snap you need a working LXD. To install LXD on Ubuntu first remove any old packages:
sudo apt-get purge lxc*
sudo apt-get purge lxd*
Get the latest LXD and configure it with:
sudo snap install lxd
lxd init --auto
Build MicroK8s with:
git clone https://github.com/ubuntu/microk8s
cd microk8s
snapcraft cleanbuild
To produce a custome build with specific component versions we need to prepare an LXC container with Ubuntu 16:04 and snapcraft:
lxc launch ubuntu:16.04 --ephemeral test-build
lxc exec test-build -- snap install snapcraft --classic
lxc exec test-build -- apt update
lxc exec test-build -- git clone https://github.com/ubuntu/microk8s
We can then set the following environment variables prior to building:
- KUBE_VERSION: kubernetes release to package. Defaults to latest stable.
- ETCD_VERSION: version of etcd. Defaults to v3.3.4.
- CNI_VERSION: version of CNI tools. Defaults to v0.7.1.
- KUBE_TRACK: kubernetes release series (e.g., 1.10) to package. Defaults to latest stable.
- ISTIO_VERSION: istio release. Defaults to v1.0.5.
- RUNC_COMMIT: the commit hash from which to build runc
- CONTAINERD_COMMIT: the commit hash from which to build containerd
For building we use snapcraft (not snapcraft cleanbuild) and we prepend and variables we need. For example to build the MicroK8s snap for Kubernetes v1.9.6 we:
lxc exec test-build -- sh -c "cd microk8s && KUBE_VERSION=v1.9.6 snapcraft"
The produced snap is inside the ephemeral LXC container, we need to copy it to the host:
lxc file pull test-build/root/microk8s/microk8s_v1.9.6_amd64.snap .
snap install microk8s_latest_amd64.snap --classic --dangerous
Check out the "MicroK8s In The Wild" page to see some interesting use cases.
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