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			- Implemented PolicyDslValidator with command-line options for strict mode and JSON output. - Created PolicySchemaExporter to generate JSON schemas for policy-related models. - Developed PolicySimulationSmoke tool to validate policy simulations against expected outcomes. - Added project files and necessary dependencies for each tool. - Ensured proper error handling and usage instructions across tools.
		
			
				
	
	
	
		
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Serverless Policy Example (serverless.stella)
Optimised for short-lived serverless workloads: focus on runtime integrity, disallow vulnerable layers entirely, and permit temporary suppressions only with strict justification windows.
policy "Serverless Tight Policy" syntax "stella-dsl@1" {
  metadata {
    description = "Aggressive blocking for serverless runtimes."
    tags = ["serverless","prod","strict"]
  }
  profile severity {
    env runtime_overrides {
      if env.runtime == "serverless" then +0.7
      if env.runtime == "batch" then +0.2
    }
  }
  rule block_any_high {
    when severity.normalized >= "High"
    then status := "blocked"
    because "Serverless workloads block High+ severities."
  }
  rule forbid_unpinned_base {
    when sbom.has_tag("image:latest-tag")
    then status := "blocked"
    because "Base image must be pinned (no :latest)."
  }
  rule zero_tolerance_vex {
    when vex.any(status == "not_affected")
    then requireVex { vendors = ["VendorX","VendorY"], justifications = ["component_not_present"] }
    because "Allow not_affected only from trusted vendors with strongest justification."
  }
  rule temporary_quiet {
    when env.deployment == "canary"
         and severity.normalized == "Medium"
    then ignore until coalesce(env.quietUntil, "2025-12-31T00:00:00Z")
    because "Allow short canary quiet window while fix rolls out."
  }
}
Commentary
- Designed for serverless tenants where redeploy cost is low and failing fast is preferred.
- forbid_unpinned_baseenforces supply-chain best practices.
- temporary_quietensures quiet windows expire automatically; require deployments to set- env.quietUntil.
- Intended to be layered on top of baseline (override per tenant) or used standalone for serverless-only accounts.
Try it out
stella policy lint examples/policies/serverless.stella
stella policy simulate P-serverless --candidate 1 \
  --sbom sbom:lambda-hello --env runtime=serverless --env deployment=canary
Compliance checklist
- Quiet window expirations tracked and documented.
- Trusted VEX vendor list reviewed quarterly.
- Deployment pipeline enforces pinned base images before approval.
- Canary deployments monitored for recurrence before ignoring Medium severity.
- Serverless teams acknowledge runbook for blocked deployments.
Last updated: 2025-10-26.