in jenkins-pipeline-shared-libraries/vars/cloud.groovy [301:311]
Map getDockerIOMirrorRegistryConfig() {
return [
name: 'docker.io',
mirrors: [
[
url : env.DOCKER_REGISTRY_MIRROR ?: 'mirror.gcr.io',
insecure: env.DOCKER_REGISTRY_MIRROR ? true : false,
]
],
]
}