cosign-provider

README

cosign-provider

cosign-provider is used for validating whether images are signed with cosign.

This repo is meant for testing Gatekeeper external data feature. Do not use for production.

Installation

• Deploy Gatekeeper with external data enabled (--enable-external-data)

• kubectl apply -f manifest

  • Update SECRET_NAME environment variable

• kubectl apply -f policy/provider.yaml

  • Update proxyURL if it's not http://cosign-provider.default:8090

• kubectl apply -f policy/template.yaml

• kubectl apply -f policy/constraint.yaml

Verification

• kubectl apply -f policy/examples/signed.yaml

  • Request should be rejected

  Error from server ([signed-image] Image gcr.io/google_containers/pause-amd64:3.0 does not contain a valid cosign signature): error when creating "policy/examples/unsigned.yaml": admission webhook "validation.gatekeeper.sh" denied the request: [signed-image] Image gcr.io/google_containers/pause-amd64:3.0 does not contain a valid cosign signature
  

• kubectl apply -f policy/examples/unsigned.yaml

  • Request should be allowed

  deployment.apps/signed-deployment created
  

Credits

Cosign image verification is based on https://github.com/dlorenc/cosigned