Nightshift is a service that will enable automatic down and upscaling of deployments within an OpenShift project at a predefined schedule. This in order to save resource usage (or use resources for something else). It will monitor and scale the namespaces according to a preset configuration.
Install in OpenShift
Nightshift can be run both from a seperate namespace, or in the namespace which it will schedule. In order to allow OpenShift scaling the services, it needs to run with a service account that has both read and edit permissions on the namespace it should control. Adding the service account can be done with the below commands, where a service account named "nightshift" is created in the project specified with "source" which has access to the project "target". If multiple projects should be scaled by nightshift, the policies should be added for each project individually.
oc create sa nightshift -n <source> oc policy add-role-to-user view system:serviceaccount:<target>:nightshift -n <source> oc policy add-role-to-user edit system:serviceaccount:<target>:nightshift -n <source>
This repository also includes an example OpenShift template, which contains the basis configuration for installing the service. The configuration is stored in a configmap, the example folder contains an example for this as well. The template includes the OpenShift oauth proxy for authentication with an OpenShift account. Access is restricted to users that have update permissions in the project where nightshift is deployed. The example template pulls the nightshift image from docker hub.
oc create configmap nightshift-config --from-file=examples/config.yaml oc process -f examples/openshift.yaml | oc apply -f - oc rollout latest dc/nightshift
Nightshift can be configured with both annotations, or via a config file. They can also be combined, where annotations always override any other configuration set.
Nightshift scales deployments according to a schedule. A schedule can be added to a pod with an annotation, or can be defined in a config file. A schedule definition contains out of 3 elements; a section defining the day(s) in the week this schedule applies to, a time and the action that should be taken.
The first section defines the day(s) of the week. This can be a combination of single day(s), a range of days, or both. Each day is specified by the first three letters of the English name. If multiple days, or ranges are specified, they should be seperated by a comma. A range is specified by two days seperated by a hyphen.
The second part defines the time. The time is specified in the timezone that has been configured in the configuration file (default is Local, which usually equals to UTC in most deployments).
The last part defines the action that needs to be taken in this time event. At this point only the number of replicas can be specified.
An example of a schedule configuration is:
Mon-Wed,Fri 9:00 replicas=1.
Saving and restoring states
Next to specifying the exact number of replicas, it is also possible to save
and restore states. In order to do this, the
can be added to the schedule. When the state should be saved, it will be saved
before actual scaling to the number of replicas. When restoring the state, if
no state is available, it will take the number of replicas that has been
(optionally) specified in the schedule. The saved state will take precedence
on the number that is set in replicas if both are configured.
By default the scanner will only scan deploymentconfigs. Statefulsets are
supported as well by use of the
statefulset scanner. This can be configured
by specifying the
type of the scanner in the scanner configuration
section. The default is
openshift which scans for deploymentconfigs.
Nightshift can be configured by both a configuration file, as well as annotations that should be set on a DeploymentConfig. These annotations will always override the configuration specified in the configuration file. The annotations supported by nightshift are:
joyrex2001.com/nightshift.schedulein which a schedule can be specified. Multiple schedules are allowed, and should be seperated with a semicolon.
joyrex2001.com/nightshift.ignorewhich can be set to
trueto ignore this deployment.
The most flexible way to configure nightshift is by using a configuration file. The configuration file allow complex schedules, with both default schedules as well as allowing to fix schedules for certain label criteria, specified with a selector.
In the below example , namespace
development will be scanned for
annotations. If a deployment in this namespace doesn't have any schedule
annotations, it will apply the default schedule. For a deployment that matches
app=shell, no schedule will be applied at all.
scanner: - namespace: - "development" default: schedule: - "Mon-Fri 9:00 replicas=1" - "Mon-Fri 18:00 replicas=0" deployment: - selector: - "app=shell" schedule: - ""
The scanner configuration will be handled top down. If a pod is found in multiple scanner configurations, only the last one will be applied.
See the examples folder for another example, which also includes basic nightshift configuration.
Nightshift is able to trigger events when it will scale. This is done by triggers. Currently there is only one type of trigger "webhook", which will call a http endpoint with a predefined configuration.
Triggers can only be configured in the configuration file. Each trigger has an id which can be used in the schedule definition to execute the trigger. When at a certain time, the endpoint is referenced by multiple schedules, it will be called only once.
An detailed reference example can be found in the examples folder in the
When the web interface is enabled, prometheus metrics will be available as well.
The endpoint of the metrics is
/metrics. If an id is set for the schedule
definitions, the current number of applied replicas for that schedule is
reflected in the
nightshift_replicas metric, and can be used to e.g.
disable alerting when nightshift downscaled the pods as planned.