Package : envoy.api.v2



Table of Contents


DeltaDiscoveryRequest and DeltaDiscoveryResponse are used in a new gRPC endpoint for Delta xDS.

With Delta xDS, the DeltaDiscoveryResponses do not need to include a full snapshot of the tracked resources. Instead, DeltaDiscoveryResponses are a diff to the state of a xDS client. In Delta XDS there are per-resource versions, which allow tracking state at the resource granularity. An xDS Delta session is always in the context of a gRPC bidirectional stream. This allows the xDS server to keep track of the state of xDS clients connected to it.

In Delta xDS the nonce field is required and used to pair DeltaDiscoveryResponse to a DeltaDiscoveryRequest ACK or NACK. Optionally, a response message level system_version_info is present for debugging purposes only.

DeltaDiscoveryRequest plays two independent roles. Any DeltaDiscoveryRequest can be either or both of: [1] informing the server of what resources the client has gained/lost interest in (using resource_names_subscribe and resource_names_unsubscribe), or [2] (N)ACKing an earlier resource update from the server (using response_nonce, with presence of error_detail making it a NACK). Additionally, the first message (for a given type_url) of a reconnected gRPC stream has a third role: informing the server of the resources (and their versions) that the client already possesses, using the initial_resource_versions field.

As with state-of-the-world, when multiple resource types are multiplexed (ADS), all requests/acknowledgments/updates are logically walled off by type_url: a Cluster ACK exists in a completely separate world from a prior Route NACK. In particular, initial_resource_versions being sent at the "start" of every gRPC stream actually entails a message for each type_url, each with its own initial_resource_versions.

Field Type Label Description
node core.Node The node making the request.
type_url string Type of the resource that is being requested, e.g.
resource_names_subscribe []string repeated DeltaDiscoveryRequests allow the client to add or remove individual
resources to the set of tracked resources in the context of a stream.
All resource names in the resource_names_subscribe list are added to the
set of tracked resources and all resource names in the resource_names_unsubscribe
list are removed from the set of tracked resources.

Unlike state-of-the-world xDS, an empty resource_names_subscribe or resource_names_unsubscribe list simply means that no resources are to be added or removed to the resource list. Like state-of-the-world xDS, the server must send updates for all tracked resources, but can also send updates for resources the client has not subscribed to.

NOTE: the server must respond with all resources listed in resource_names_subscribe, even if it believes the client has the most recent version of them. The reason: the client may have dropped them, but then regained interest before it had a chance to send the unsubscribe message. See DeltaSubscriptionStateTest.RemoveThenAdd.

These two fields can be set in any DeltaDiscoveryRequest, including ACKs and initial_resource_versions.

A list of Resource names to add to the list of tracked resources. | | resource_names_unsubscribe | []string | repeated | A list of Resource names to remove from the list of tracked resources. | | initial_resource_versions | []DeltaDiscoveryRequest.InitialResourceVersionsEntry | repeated | Informs the server of the versions of the resources the xDS client knows of, to enable the client to continue the same logical xDS session even in the face of gRPC stream reconnection. It will not be populated: [1] in the very first stream of a session, since the client will not yet have any resources, [2] in any message after the first in a stream (for a given type_url), since the server will already be correctly tracking the client's state. (In ADS, the first message of each type_url of a reconnected stream populates this map.) The map's keys are names of xDS resources known to the xDS client. The map's values are opaque resource versions. | | response_nonce | string | | When the DeltaDiscoveryRequest is a ACK or NACK message in response to a previous DeltaDiscoveryResponse, the response_nonce must be the nonce in the DeltaDiscoveryResponse. Otherwise (unlike in DiscoveryRequest) response_nonce must be omitted. | | error_detail | google.rpc.Status | | This is populated when the previous DiscoveryResponse (envoy_api_msg_DiscoveryResponse) failed to update configuration. The message field in error_details provides the Envoy internal exception related to the failure. |


Field Type Label Description
key string
value string


Field Type Label Description
system_version_info string The version of the response data (used for debugging).
resources []Resource repeated The response resources. These are typed resources, whose types must match
the type_url field.
type_url string Type URL for resources. Identifies the xDS API when muxing over ADS.
Must be consistent with the type_url in the Any within 'resources' if 'resources' is non-empty.
removed_resources []string repeated Resources names of resources that have be deleted and to be removed from the xDS Client.
Removed resources for missing resources can be ignored.
nonce string The nonce provides a way for DeltaDiscoveryRequests to uniquely
reference a DeltaDiscoveryResponse when (N)ACKing. The nonce is required.


A DiscoveryRequest requests a set of versioned resources of the same type for a given Envoy node on some API.

Field Type Label Description
version_info string The version_info provided in the request messages will be the version_info
received with the most recent successfully processed response or empty on
the first request. It is expected that no new request is sent after a
response is received until the Envoy instance is ready to ACK/NACK the new
configuration. ACK/NACK takes place by returning the new API config version
as applied or the previous API config version respectively. Each type_url
(see below) has an independent version associated with it.
node core.Node The node making the request.
resource_names []string repeated List of resources to subscribe to, e.g. list of cluster names or a route
configuration name. If this is empty, all resources for the API are
returned. LDS/CDS may have empty resource_names, which will cause all
resources for the Envoy instance to be returned. The LDS and CDS responses
will then imply a number of resources that need to be fetched via EDS/RDS,
which will be explicitly enumerated in resource_names.
type_url string Type of the resource that is being requested, e.g.
"type.googleapis.com/envoy.api.v2.ClusterLoadAssignment". This is implicit
in requests made via singleton xDS APIs such as CDS, LDS, etc. but is
required for ADS.
response_nonce string nonce corresponding to DiscoveryResponse being ACK/NACKed. See above
discussion on version_info and the DiscoveryResponse nonce comment. This
may be empty only if 1) this is a non-persistent-stream xDS such as HTTP,
or 2) the client has not yet accepted an update in this xDS stream (unlike
delta, where it is populated only for new explicit ACKs).
error_detail google.rpc.Status This is populated when the previous DiscoveryResponse (envoy_api_msg_DiscoveryResponse)
failed to update configuration. The message field in error_details provides the Envoy
internal exception related to the failure. It is only intended for consumption during manual
debugging, the string provided is not guaranteed to be stable across Envoy versions.


Field Type Label Description
version_info string The version of the response data.
resources []google.protobuf.Any repeated The response resources. These resources are typed and depend on the API being called.
canary bool [#not-implemented-hide:]
Canary is used to support two Envoy command line flags:


Field Type Label Description
name string The resource's name, to distinguish it from others of the same type of resource.
aliases []string repeated [#not-implemented-hide:]
The aliases are a list of other names that this resource can go by.
version string The resource level version. It allows xDS to track the state of individual
resource google.protobuf.Any The resource being tracked.