const (
    // DefaultSystemNamespace default value for SystemNamespace
    DefaultSystemNamespace = "istio-system"

    // ValuesMcpFile for Istio Helm deployment.
    E2EValuesFile = "test-values/values-e2e.yaml"

    // DefaultDeployTimeout for Istio
    DefaultDeployTimeout = time.Second * 300

    // TODO(https://github.com/istio/istio/issues/12606): This timeout is insanely large, but Prow seems to take a lot of time
    //  pulling images.
    // DefaultCIDeployTimeout for Istio
    DefaultCIDeployTimeout = time.Minute * 20

    // DefaultUndeployTimeout for Istio.
    DefaultUndeployTimeout = time.Second * 300

    // DefaultCIUndeployTimeout for Istio.
    DefaultCIUndeployTimeout = time.Second * 900

    // DefaultIstioChartRepo for Istio.
    DefaultIstioChartRepo = "https://gcsweb.istio.io/gcs/istio-prerelease/daily-build/release-1.1-latest-daily/charts/"
)

type Config struct {
    // The namespace where the Istio components (<=1.1) reside in a typical deployment (default: "istio-system").
    SystemNamespace string

    // The namespace in which istio ca and cert provisioning components are deployed.
    IstioNamespace string

    // The namespace in which config, discovery and auto-injector are deployed.
    ConfigNamespace string

    // The namespace in which mixer, kiali, tracing providers, graphana, prometheus are deployed.
    TelemetryNamespace string

    // The namespace in which istio policy checker is deployed.
    PolicyNamespace string

    // The namespace in which istio ingressgateway is deployed
    IngressNamespace string

    // The namespace in which istio egressgateway is deployed
    EgressNamespace string

    // DeployTimeout the timeout for deploying Istio.
    DeployTimeout time.Duration

    // UndeployTimeout the timeout for undeploying Istio.
    UndeployTimeout time.Duration

    ChartRepo string

    // The top-level Helm chart dir.
    ChartDir string

    // The top-level Helm Crds files dir.
    CrdsFilesDir string

    // The Helm values file to be used.
    ValuesFile string

    // Overrides for the Helm values file.
    Values map[string]string

    // Indicates that the test should deploy Istio into the target Kubernetes cluster before running tests.
    DeployIstio bool

    // Do not wait for the validation webhook before completing the deployment. This is useful for
    // doing deployments without Galley.
    SkipWaitForValidationWebhook bool

    // CustomSidecarInjectorNamespace allows injecting the sidecar from the specified namespace.
    // if the value is "", use the default sidecar injection instead.
    CustomSidecarInjectorNamespace string
}

type Instance interface {
    resource.Resource

    Settings() Config
}

type SetupConfigFn func(cfg *Config)