README
¶
Flatcar Linux Update Operator
Flatcar Linux Update Operator is a node reboot controller for Kubernetes running Flatcar Container Linux images. When a reboot is needed after updating the system via update_engine, the operator will drain the node before rebooting it.
Flatcar Linux Update Operator fulfills the same purpose as locksmith, but has better integration with Kubernetes by explicitly marking a node as unschedulable and deleting pods on the node before rebooting.
Design
Flatcar Linux Update Operator is divided into two parts: update-operator and update-agent.
update-agent runs as a DaemonSet on each node, waiting for a UPDATE_STATUS_UPDATED_NEED_REBOOT signal via D-Bus from update_engine.
It will indicate via node annotations that it needs a reboot.
update-operator runs as a Deployment, watching changes to node annotations and reboots the nodes as needed.
It coordinates the reboots of multiple nodes in the cluster, ensuring that not too many are rebooting at once.
Currently, update-operator only reboots one node at a time.
Requirements
- A Kubernetes cluster (>= 1.6) running on Flatcar Container Linux
- The
update-engine.servicesystemd unit on each machine should be unmasked, enabled and started in systemd - The
locksmithd.servicesystemd unit on each machine should be masked and stopped in systemd
To unmask a service, run systemctl unmask <name>.
To enable a service, run systemctl enable <name>.
To start/stop a service, run systemctl start <name> or systemctl stop <name> respectively.
or using a Container Linux Config file:
systemd:
units:
- name: locksmithd.service
mask: true
- name: update-engine.service
enabled: true
Usage
Create the update-operator deployment and update-agent daemonset.
kubectl kustomize examples/deploy | kubectl apply -f-
Test
To test that it is working, you can SSH to a node and trigger an update check by running update_engine_client -check_for_update or simulate a reboot is needed by running locksmithctl send-need-reboot.
You can also annotate one of your nodes using the command below. Shortly after, you should see the Node being drained as a preparation for the reboot.
export NODE="<node name>"
kubectl annotate node $NODE --overwrite \
flatcar-linux-update.v1.flatcar-linux.net/reboot-needed="true"
Directories
¶
| Path | Synopsis |
|---|---|
|
cmd
|
|
|
update-agent
Package main provides executable for FLUO agent.
|
Package main provides executable for FLUO agent. |
|
update-operator
Package main provides executable for FLUO.
|
Package main provides executable for FLUO. |
|
pkg
|
|
|
agent
Package agent implements Flatcar Linux Update Operator agent, which role is to run on every Flatcar Node on the cluster, watch update_engine for status updates, propagate them to operator via Node labels and annotations and react on operator decisions about when to drain a node and reboot to finish upgrade process.
|
Package agent implements Flatcar Linux Update Operator agent, which role is to run on every Flatcar Node on the cluster, watch update_engine for status updates, propagate them to operator via Node labels and annotations and react on operator decisions about when to drain a node and reboot to finish upgrade process. |
|
constants
Package constants has Kubernetes label and annotation constants shared by the update-agent and update-operator.
|
Package constants has Kubernetes label and annotation constants shared by the update-agent and update-operator. |
|
dbus
Package dbus provides a helper function for creating new D-Bus client.
|
Package dbus provides a helper function for creating new D-Bus client. |
|
k8sutil
Package k8sutil provides various wrappers over Kubernetes tooling.
|
Package k8sutil provides various wrappers over Kubernetes tooling. |
|
operator
Package operator contains main implementation of Flatcar Linux Update Operator.
|
Package operator contains main implementation of Flatcar Linux Update Operator. |
|
updateengine
Package updateengine provides an interface for communicating with update_engine via D-BUS interface on the host.
|
Package updateengine provides an interface for communicating with update_engine via D-BUS interface on the host. |
|
version
Package version is used to store the version information for the built binaries.
|
Package version is used to store the version information for the built binaries. |