var (
    SidecarInject                         = workloadAnnotation(annotation.SidecarInject.Name, "true")
    SidecarStatus                         = workloadAnnotation(annotation.SidecarStatus.Name, "")
    SidecarRewriteAppHTTPProbers          = workloadAnnotation(annotation.SidecarRewriteAppHTTPProbers.Name, "")
    SidecarProxyImage                     = workloadAnnotation(annotation.SidecarProxyImage.Name, "")
    SidecarInterceptionMode               = workloadAnnotation(annotation.SidecarInterceptionMode.Name, "")
    SidecarStatusPort                     = workloadAnnotation(annotation.SidecarStatusPort.Name, "")
    SidecarReadinessInitialDelaySeconds   = workloadAnnotation(annotation.SidecarStatusReadinessInitialDelaySeconds.Name, "")
    SidecarReadinessPeriodSeconds         = workloadAnnotation(annotation.SidecarStatusReadinessPeriodSeconds.Name, "")
    SidecarReadinessFailoverThreshold     = workloadAnnotation(annotation.SidecarStatusReadinessFailureThreshold.Name, "")
    SidecarApplicationPorts               = workloadAnnotation(annotation.SidecarStatusReadinessApplicationPorts.Name, "")
    SidecarTrafficIncludeOutboundIPRanges = workloadAnnotation(annotation.SidecarTrafficIncludeOutboundIPRanges.Name, "")
    SidecarTrafficExcludeOutboundIPRanges = workloadAnnotation(annotation.SidecarTrafficExcludeOutboundIPRanges.Name, "")
    SidecarTrafficIncludeInboundPorts     = workloadAnnotation(annotation.SidecarTrafficIncludeInboundPorts.Name, "")
    SidecarTrafficExcludeInboundPorts     = workloadAnnotation(annotation.SidecarTrafficExcludeInboundPorts.Name, "")
    SidecarTrafficKubeVirtInterfaces      = workloadAnnotation(annotation.SidecarTrafficKubevirtInterfaces.Name, "")

    KubeServiceAccountsOnVMA = serviceAnnotation(annotation.AlphaKubernetesServiceAccounts.Name, "")
    CanonicalServiceAccounts = serviceAnnotation(annotation.AlphaCanonicalServiceAccounts.Name, "")
    ServiceExport            = serviceAnnotation(annotation.NetworkingExportTo.Name, "")
    WorkloadIdentity         = workloadAnnotation(annotation.AlphaIdentity.Name, "")
)

type Annotation struct {
    Name    string
    Type    AnnotationType
    Default AnnotationValue
}

type AnnotationType string

const (
    ServiceAnnotation  AnnotationType = "service"
    WorkloadAnnotation AnnotationType = "workload"
)

type AnnotationValue struct {
    Value string
}

type Annotations map[Annotation]*AnnotationValue

type Builder interface {
    // With adds a new Echo configuration to the Builder. Once built, the instance
    // pointer will be updated to point at the new Instance.
    With(i *Instance, cfg Config) Builder

    // Build and initialize all Echo Instances. Upon returning, the Instance pointers
    // are assigned and all Instances are ready to communicate with each other.
    Build() error
    BuildOrFail(t test.Failer)
}

type CallOptions struct {
    // Target instance of the call. Required.
    Target Instance

    // Port on the target Instance. Either Port or PortName must be specified.
    Port *Port

    // PortName of the port on the target Instance. Either Port or PortName must be specified.
    PortName string

    // Scheme to be used when making the call. If not provided, an appropriate default for the
    // port will be used (if feasible).
    Scheme scheme.Instance

    // Host specifies the host to be used on the request. If not provided, an appropriate
    // default is chosen for the target Instance.
    Host string

    // Path specifies the URL path for the HTTP(s) request.
    Path string

    // Count indicates the number of exchanges that should be made with the service endpoint.
    // If Count <= 0, defaults to 1.
    Count int

    // Headers indicates headers that should be sent in the request. Ignored for WebSocket calls.
    Headers http.Header

    // Timeout used for each individual request. Must be > 0, otherwise 30 seconds is used.
    Timeout time.Duration

    // Message to be sent if this is a GRPC request
    Message string
}

type Config struct {
    // Namespace of the echo Instance. If not provided, a default namespace "apps" is used.
    Namespace namespace.Instance

    // Domain of the echo Instance. If not provided, a default will be selected.
    Domain string

    // Galley component (may be required, depending on the environment/configuration).
    Galley galley.Instance

    // Pilot component reference (may be required, depending on the environment/configuration).
    Pilot pilot.Instance

    // Service indicates the service name of the Echo application.
    Service string

    // Version indicates the version path for calls to the Echo application.
    Version string

    // Locality (k8s only) indicates the locality of the deployed app.
    Locality string

    // Headless (k8s only) indicates that no ClusterIP should be specified.
    Headless bool

    // ServiceAccount (k8s only) indicates that a service account should be created
    // for the deployment.
    ServiceAccount bool

    // Ports for this application. Port numbers may or may not be used, depending
    // on the implementation.
    Ports []Port

    // Annotations provides metadata hints for deployment of the instance.
    Annotations Annotations

    // IncludeInboundPorts provides the ports that inbound listener should capture
    // "*" means capture all.
    IncludeInboundPorts string

    // ReadinessTimeout specifies the timeout that we wait the application to
    // become ready.
    ReadinessTimeout time.Duration
}

type Instance interface {
    resource.Resource

    // Config returns the configuration of the Echo instance.
    Config() Config

    // Address of the service (e.g. Kubernetes cluster IP). May be "" if headless.
    Address() string

    // WaitUntilCallable waits until each of the provided instances are callable from
    // this Instance. If this instance has a sidecar, this waits until Envoy has
    // received outbound configuration (e.g. clusters, routes, listeners) for every
    // port.
    WaitUntilCallable(instances ...Instance) error
    WaitUntilCallableOrFail(t test.Failer, instances ...Instance)

    // Workloads retrieves the list of all deployed workloads for this Echo service.
    // Guarantees at least one workload, if error == nil.
    Workloads() ([]Workload, error)
    WorkloadsOrFail(t test.Failer) []Workload

    // Call makes a call from this Instance to a target Instance.
    Call(options CallOptions) (client.ParsedResponses, error)
    CallOrFail(t test.Failer, options CallOptions) client.ParsedResponses
}

type Port struct {
    // Name of this port
    Name string

    // Protocol to be used for the port.
    Protocol protocol.Instance

    // ServicePort number where the service can be reached. Does not necessarily
    // map to the corresponding port numbers for the instances behind the
    // service.
    ServicePort int

    // InstancePort number where this instance is listening for connections.
    // This need not be the same as the ServicePort where the service is accessed.
    InstancePort int
}

type Sidecar interface {
    // NodeID returns the node ID used for uniquely identifying this sidecar to Pilot.
    NodeID() string

    // Info about the Envoy instance.
    Info() (*envoyAdmin.ServerInfo, error)
    InfoOrFail(t test.Failer) *envoyAdmin.ServerInfo

    // Config of the Envoy instance.
    Config() (*envoyAdmin.ConfigDump, error)
    ConfigOrFail(t test.Failer) *envoyAdmin.ConfigDump

    // WaitForConfig queries the Envoy configuration an executes the given accept handler. If the
    // response is not accepted, the request will be retried until either a timeout or a response
    // has been accepted.
    WaitForConfig(accept func(*envoyAdmin.ConfigDump) (bool, error), options ...retry.Option) error
    WaitForConfigOrFail(t test.Failer, accept func(*envoyAdmin.ConfigDump) (bool, error), options ...retry.Option)

    // Clusters for the Envoy instance
    Clusters() (*envoyAdmin.Clusters, error)
    ClustersOrFail(t test.Failer) *envoyAdmin.Clusters

    // Listeners for the Envoy instance
    Listeners() (*envoyAdmin.Listeners, error)
    ListenersOrFail(t test.Failer) *envoyAdmin.Listeners

    // Logs returns the logs for the sidecar container
    Logs() (string, error)
    // LogsOrFail returns the logs for the sidecar container, or aborts if an error is found
    LogsOrFail(t test.Failer) string
}

type Workload interface {
    // Address returns the network address of the endpoint.
    Address() string

    // Sidecar if one was specified.
    Sidecar() Sidecar

    // ForwardEcho executes specific call from this workload.
    ForwardEcho(context.Context, *proto.ForwardEchoRequest) (client.ParsedResponses, error)

    // Logs returns the logs for the app container
    Logs() (string, error)
    // LogsOrFail returns the logs for the app container, or aborts if an error is found
    LogsOrFail(t test.Failer) string
}