Silta downscaler

About

Silta downscaler is a set of two applications that allows saving resources by suspending deployments on a time based schedule.

• downscaler.js is a cronjob initiated process that selects Ingress resources with special annotations in your cluster, marking deployments that can be downscaled. When an application is downscaled, kubernetes service type is changed to externalName and pointed to placeholder site.
• index.js, provides placeholder site that allows downscaled application to be be scaled back up.

The Silta downscaler is, obviously, meant for use on non-production clusters.

Supported versions

• Networking API V1 is only available since kubernetes v1.19. Older versions of downscaler support older kubernetes versions.

Development

Downscaler cronjob test:

PLACEHOLDER_SERVICE_NAME=silta-cluster-placeholder-upscaler \
PLACEHOLDER_SERVICE_NAMESPACE=silta-cluster \
PLACEHOLDER_PROXY_IMAGE=wunderio/silta-downscaler:v1-proxy \
DEFAULT_MIN_AGE=1h \
RELEASE_MIN_AGE='{"^(dev|develop|development)":"2w","^(master|main|stage|staging)":"4w","^dependabot":"1h","^production":"10y"}' \
node downscale.js

Terminal log from downscaler.js

Marked ingress drupal-project-k8s/cli-test-drupal as down
Downscaled deployment drupal-project-k8s/cli-test-drupal from 1 to 0
Downscaled deployment drupal-project-k8s/cli-test-shell from 1 to 0
Suspended cronjob drupal-project-k8s/cli-test-cron-drupal
Downscaled statefulset drupal-project-k8s/cli-test-mariadb from 1 to 0

Placeholder site test:

node index.js

curl -X POST "http://localhost:3000/upscale?domain=cli-test.drupal-project-k8s.[cluster-domain]
# Successful response:
# {"message":"cli-test-drupal triggered"}

# Repeated or incorrect request response
# Not Found

Terminal log from index.js

node ./index.js
Example app listening on port 3000!
Requesting to scale cli-test-drupal to 1 replica(s)
Requesting to scale cli-test-shell to 1 replica(s)
Requesting to scale cli-test-mariadb to 1 replica(s)
Updated last-update annotation on drupal-project-k8s/cli-test-drupal ingress
Unsuspended cronjob drupal-project-k8s/cli-test-cron-drupal
Upscaled deployment drupal-project-k8s/cli-test-shell from 0 to 1
Upscaled statefulset drupal-project-k8s/cli-test-mariadb from 0 to 1
Upscaled deployment drupal-project-k8s/cli-test-drupal from 0 to 1
drupal-project-k8s/release=cli-test selector resources are ready
drupal-project-k8s/app.kubernetes.io/instance=cli-test selector resources are ready
Reset service drupal-project-k8s/cli-test-drupal to original service
Someone tried to upscale cli-test.drupal-project-k8s.[cluster-domain] via ingress/cli-test-drupal

Docker image build

Automated builds:

Tag a new release in github, docker hub integration will build and publish the images automatically.

Manual builds (only when automated builds are not working):

docker build --tag 'wunderio/silta-downscaler:v1' --tag 'wunderio/silta-downscaler:v1.X' --tag 'wunderio/silta-downscaler:v1.X.Y' .
docker push wunderio/silta-downscaler:v1 
docker push wunderio/silta-downscaler:v1.X
docker push wunderio/silta-downscaler:v1.X.Y

docker build --tag 'wunderio/silta-downscaler:v1-proxy' proxy/
docker push wunderio/silta-downscaler:v1-proxy