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Harness Policy as a Code using OPA

Before you begin​

  1. Harness Governance Overview
  2. Harness Governance Quickstart
  3. Policies use OPA authoring language Rego. For more information, go to OPA Policy Authoring.

Introduction​

Harness Policy As Code uses Open Policy Agent (OPA) as the central service to store and enforce policies for the different entities and processes across the Harness platform.

You can centrally define and store policies and then select where (which entities) and when (which events) they will be applied.

Examples with Harness OPA using Scorecards​

Presently we support two set of OPA Policies that could be applied to any CD pipeline.

Example A: Pipeline > On Save (Policy Used: IDP Scorecard)​

When a Pipeline is saved, the service used in the pipeline should have a score more than the set limit, before being able to save the pipeline.

Rego​

package pipeline

# Deny pipelines that are configured for service name 'orderService'
# ... and score of 'Service Maturity' scorecard is less than 50.
# Absence of either of these will not halt the pipeline execution
deny[msg] {
    stage = input.pipeline.stages[_].stage      # Find all stages ...
    stage.type == "Deployment"                  # ... that are deployments

    scorecard := stage.spec.idpScorecard.orderService[_]
    scorecard.name == "Service Maturity"
    scorecard.score < 50

    msg := sprintf("orderService has score less than 50, current score: '%v'", [scorecard.score])
}

In the REGO script we use stage.spec.idpScorecard.orderService[_] to fetch the Harness service ID mentioned in the annotation harness.io/cd-serviceId: <SERVICE_IDENTIFIER>. If you have followed the onboarding guide then this annotation is auto ingested in your catalog-info.yaml or-else you have to manually add it.

Success:​

Check the Score for the service you're using in your pipeline to be above the set limit so that when you save the Pipeline, the policy rule is evaluated and returns success.

Warning:​

A warning message appears: Your Score for the service used needs to be more than 50. If you save the Pipeline and deploy, Harness will throw an error.

Failure:​

You configure a Pipeline with a Deploy stage that deploys to a prod environment with a service having Score less than the set limit. When you save the Pipeline, Harness throws an error message indicating the rule was enforced and the Pipeline fails validation.

Example B: Pipeline > On Run (Policy Used: IDP Scorecard For Multi Service )​

On deployment, I need all the services used in my pipeline to have a Score above 50.

package pipeline

# Deny pipelines that are configured for all services
# ... if the score of 'Service Maturity' scorecard is less than 50.
# Absence of either of these will not halt the pipeline execution
deny[msg] {
    stage = input.pipeline.stages[_].stage      # Find all stages ...
    stage.type == "Deployment"                  # ... that are deployments

    some key                                   # run through all services
    scorecard = stage.spec.idpScorecard[key][_]
    scorecard.name == "Service Maturity"
    scorecard.score < 50

    msg := sprintf("service '%s' has score less than 50, Actual Score: '%v'", [key, scorecard.score])
}

Success:​

You deploy the Pipeline and during the dry run the Scores of all the services you have used in the pipeline turns to be more than the set limit(here: 50). As a result, the dry run progresses. Harness indicates that the rule was evaluated and the action was valid.

Failure:​

Some of the services you have used have a score less than the set limit(here: 50). As a result, the dry run fails. Harness indicates that a rule was enforced and the deployment is prevented.