diff --git a/docs/configuration/nodegroup.md b/docs/configuration/nodegroup.md index 888f7676..a1ba2401 100644 --- a/docs/configuration/nodegroup.md +++ b/docs/configuration/nodegroup.md @@ -27,6 +27,7 @@ node_groups: soft_delete_grace_period: 1m hard_delete_grace_period: 10m taint_effect: NoExecute + max_node_age: 24h aws: fleet_instance_ready_timeout: 1m launch_template_id: lt-1a2b3c4d @@ -258,3 +259,17 @@ be taken from the launch template. Tag ASG and Fleet Request resources used by Escalator with the metatdata key-value pair `k8s.io/atlassian-escalator/enabled`:`true`. Tagging doesn't alter the functionality of Escalator. Read more about tagging your AWS resources [here](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/Using_Tags.html). + +### `max_node_age` + +`max_node_age` allows the configuration of a maximum age for nodes in the node group when the node group has scaled down +to the minimum node group size. When at the minimum node grop size, Escalator will trigger a scale up by a minimum of 1 +if there are any nodes exceeding this max node age in an effort to have the old node rotated out. + +This is to ensure that nodes in the node group are kept relatively new to pick up any changes to the launch +configuration or launch template. + +When not at the minimum, the natural scaling up and down of the node group will ensure new nodes are introduced to the +node group. + +This is an optional feature and by default is disabled.