Set up Operational Rules

You can set up operational rules in the AppConfiguration model via the opsRule field and corresponding platform configurations in the workspace directory. The opsRule is the collection of operational rule requirements for the application that are used as a preemptive measure to police and stop any unwanted changes.

Prerequisites

Please refer to the prerequisites in the guide for deploying an application.

The example below also requires you to have initialized the project using the kusion workspace create and kusion init command, which will create a workspace and also generate a kcl.mod file under the stack directory.

Managing Workspace Configuration

In the first guide in this series, we introduced a step to initialize a workspace with an empty configuration. The same empty configuration will still work in this guide, no changes are required there.

However, if you (or the platform team) would like to set default values for the opsRule to standardize the behavior of applications, you can do so by updating the ~/dev.yaml:

modules:
    opsRule:
        default:
            maxUnavailable: "40%"

Please note that the maxUnavailable in the workspace configuration only works as a default value and will be overridden by the value set in the application configuration.

The workspace configuration need to be updated with the command:

kusion workspace update dev -f ~/dev.yaml

info

If the platform engineers have set the default workload to Kusion Operation and installed the Kusion Operation controllers properly, the opsRules module will generate a PodTransitionRule instead of updating the maxUnavailable value in the deployment

Example

Add the opsRule snippet to the AppConfiguration in simple-service/dev/main.k:

import catalog.models.schema.v1 as ac
import catalog.models.schema.v1.workload as wl
import catalog.models.schema.v1.workload.container as c
import catalog.models.schema.v1.trait as t

helloworld: ac.AppConfiguration {
    workload: wl.Service {
        ...
    }
    # Configure the maxUnavailable rule
    opsRule = t.OpsRule {
        maxUnavailable: "30%"
    }
}

Applying

Re-run steps in Applying, resource scaling is completed.

$ kusion apply
✔︎  Generating Intent in the Stack dev...                                                                                                                                                                                                     
Stack: dev  ID                                                               Action
* ├─     v1:Namespace:simple-service                                      UnChanged
* ├─     v1:Service:simple-service:simple-service-dev-helloworld-private  UnChanged
* └─     apps/v1:Deployment:simple-service:simple-service-dev-helloworld  Update


? Do you want to apply these diffs? yes
Start applying diffs ...
 SUCCESS  UnChanged v1:Namespace:simple-service, skip                                                                                                                                                                                         
 SUCCESS  UnChanged v1:Service:simple-service:simple-service-dev-helloworld-private, skip                                                                                                                                                     
 SUCCESS  Update apps/v1:Deployment:simple-service:simple-service-dev-helloworld success                                                                                                                                                      
Update apps/v1:Deployment:simple-service:simple-service-dev-helloworld success [3/3] ███████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████ 100% | 0s
Apply complete! Resources: 0 created, 1 updated, 0 deleted.

Validation

We can verify the application deployment strategy now has the updated attributes maxUnavailable: 30% in the container configuration:

kubectl get deployment -n simple-service -o yaml
...
apiVersion: apps/v1
    kind: Deployment
...
  spec:
    strategy:
      rollingUpdate:
        maxUnavailable: 30%
      type: RollingUpdate

...