package istio.mcp.v1alpha1

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The aggregated mesh configuration services allow a single management server, via a single gRPC stream, to deliver all API updates.

• rpc IncrementalAggregatedResources (stream IncrementalMeshConfigRequest, stream IncrementalMeshConfigResponse)

  mcp.proto:181

  IncrementalAggregatedResources provides the ability to incrementally update the resources on the client. This supports the goal of scalability of MCP resources.

  message IncrementalMeshConfigRequest

  mcp.proto:106

  IncrementalMeshConfigRequest are be sent in 2 situations: 1. Initial message in a MCP bidirectional gRPC stream. 2. As a ACK or NACK response to a previous IncrementalMeshConfigResponse. In this case the response_nonce is set to the nonce value in the Response. ACK or NACK is determined by the absence or presence of error_detail.

  • optional SinkNode sink_node = 1

    The sink node making the request.

  • string type_url = 2

    Type of the resource that is being requested, e.g. "type.googleapis.com/istio.io.networking.v1alpha3.VirtualService".

  • map<string, string> initial_resource_versions = 3

    When the IncrementalMeshConfigRequest is the first in a stream, the initial_resource_versions must be populated. Otherwise, initial_resource_versions must be omitted. The keys are the resources names of the MCP resources known to the MCP client. The values in the map are the associated resource level version info.

  • string response_nonce = 4

    When the IncrementalMeshConfigRequest is a ACK or NACK message in response to a previous IncrementalMeshConfigResponse, the response_nonce must be the nonce in the IncrementalMeshConfigResponse. Otherwise response_nonce must be omitted.

  • optional google.rpc.Status error_detail = 5

    This is populated when the previous IncrementalMeshConfigResponses failed to update configuration. The *message* field in *error_details* provides the client internal exception related to the failure.

  message IncrementalMeshConfigResponse

  mcp.proto:146

  IncrementalMeshConfigResponses do not need to include a full snapshot of the tracked resources. Instead they are a diff to the state of a MCP client. Per resource versions allow servers and clients to track state at the resource granularity. An MCP incremental session is always in the context of a gRPC bidirectional stream. This allows the MCP server to keep track of the state of MCP clients connected to it. In Incremental MCP the nonce field is required and used to pair IncrementalMeshConfigResponse to an IncrementalMeshConfigRequest ACK or NACK. Optionally, a response message level system_version_info is present for debugging purposes only.

  • string system_version_info = 1

    The version of the response data (used for debugging).

  • repeated Resource resources = 2

    The response resources wrapped in the common MCP *Resource* message. These are typed resources that match the type url in the IncrementalMeshConfigRequest.

  • repeated string removed_resources = 3

    Resources names of resources that have be deleted and to be removed from the MCP Client. Removed resources for missing resources can be ignored.

  • string nonce = 4

    The nonce provides a way for IncrementalMeshConfigRequests to uniquely reference an IncrementalMeshConfigResponse. The nonce is required.

• rpc StreamAggregatedResources (stream MeshConfigRequest, stream MeshConfigResponse)

  mcp.proto:174

  StreamAggregatedResources provides the ability to carefully sequence updates across multiple resource types. A single stream is used with multiple independent MeshConfigRequest / MeshConfigResponses sequences multiplexed via the type URL.

  message MeshConfigRequest

  mcp.proto:40

  A MeshConfigRequest requests a set of versioned resources of the same type for a given client.

  • string version_info = 1

    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 client 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.

  • optional SinkNode sink_node = 2

    The sink node making the request.

  • string type_url = 3

    Type of the resource that is being requested, e.g. "type.googleapis.com/istio.io.networking.v1alpha3.VirtualService".

  • string response_nonce = 4

    The nonce corresponding to MeshConfigResponse being ACK/NACKed. See above discussion on version_info and the MeshConfigResponse nonce comment. This may be empty if no nonce is available, e.g. at startup.

  • optional google.rpc.Status error_detail = 5

    This is populated when the previous MeshConfigResponse failed to update configuration. The *message* field in *error_details* provides the client 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 client versions.

  message MeshConfigResponse

  mcp.proto:75

  A MeshConfigResponse delivers a set of versioned resources of the same type in response to a MeshConfigRequest.

  • string version_info = 1

    The version of the response data.

  • repeated Resource resources = 2

    The response resources wrapped in the common MCP *Resource* message.

  • string type_url = 3

    Type URL for resources wrapped in the provided resources(s). This must be consistent with the type_url in the wrapper messages if resources is non-empty.

  • string nonce = 4

    The nonce provides a way to explicitly ack a specific MeshConfigResponse in a following MeshConfigRequest. Additional messages may have been sent by client to the management server for the previous version on the stream prior to this MeshConfigResponse, that were unprocessed at response send time. The nonce allows the management server to ignore any further MeshConfigRequests for the previous version until a MeshConfigRequest bearing the nonce.

Service where the source is the gRPC client. The source is responsible for initiating connections and opening streams.

• rpc EstablishResourceStream (stream Resources, stream RequestResources)

  mcp.proto:307

  The source, acting as gRPC client, establishes a new resource stream with the sink. The sink sends RequestResources message to and receives Resources messages from the source.

Service where the sink is the gRPC client. The sink is responsible for initiating connections and opening streams.

• rpc EstablishResourceStream (stream RequestResources, stream Resources)

  mcp.proto:298

  The sink, acting as gRPC client, establishes a new resource stream with the source. The sink sends RequestResources message to and receives Resources messages from the source.

Metadata information that all resources within the Mesh Configuration Protocol must have.

Used in: Resource

• string name = 1

  Fully qualified name of the resource. Unique in context of a collection. The fully qualified name consists of a directory and basename. The directory identifies the resources location in a resource hierarchy. The basename identifies the specific resource name within the context of that directory. The directory and basename are composed of one or more segments. Segments must be valid [DNS labels](https://tools.ietf.org/html/rfc1123). "/" is the delimiter between segments The rightmost segment is the basename. All segments to the left of the basename form the directory. Segments moving towards the left represent higher positions in the resource hierarchy, similar to reverse DNS notation. e.g. /<org>/<team>/<subteam>/<resource basename> An empty directory indicates a resource that is located at the root of the hierarchy, e.g. /<globally scoped resource> On Kubernetes the resource hierarchy is two-levels: namespaces and cluster-scoped (i.e. global). Namespace resources fully qualified name is of the form: "<k8s namespace>/<k8s resource name>" Cluster scoped resources are located at the root of the hierarchy and are of the form: "/<k8s resource name>"

• optional google.protobuf.Timestamp create_time = 2

  The creation timestamp of the resource.

• string version = 3

  Resource version. This is used to determine when resources change across resource updates. It should be treated as opaque by consumers/sinks.

• map<string, string> labels = 4

  Map of string keys and values that can be used to organize and categorize resources within a collection.

• map<string, string> annotations = 5

  Map of string keys and values that can be used by source and sink to communicate arbitrary metadata about this resource.

A RequestResource can be sent in two situations: Initial message in an MCP bidirectional change stream as an ACK or NACK response to a previous Resources. In this case the response_nonce is set to the nonce value in the Resources. ACK/NACK is determined by the presence of error_detail. * ACK (nonce!="",error_details==nil) * NACK (nonce!="",error_details!=nil) * New/Update request (nonce=="",error_details ignored)

Used as request type in: ResourceSource.EstablishResourceStream

Used as response type in: ResourceSink.EstablishResourceStream

• optional SinkNode sink_node = 1

  The sink node making the request.

• string collection = 2

  Type of resource collection that is being requested, e.g. istio/networking/v1alpha3/VirtualService k8s/<apiVersion>/<kind>

• map<string, string> initial_resource_versions = 3

  When the RequestResources is the first in a stream, the initial_resource_versions must be populated. Otherwise, initial_resource_versions must be omitted. The keys are the resources names of the MCP resources known to the MCP client. The values in the map are the associated resource level version info.

• string response_nonce = 4

  When the RequestResources is an ACK or NACK message in response to a previous RequestResources, the response_nonce must be the nonce in the RequestResources. Otherwise response_nonce must be omitted.

• optional google.rpc.Status error_detail = 5

  This is populated when the previously received resources could not be applied The *message* field in *error_details* provides the source internal error related to the failure.

• bool incremental = 6

  Request an incremental update for the specified collection. The source may choose to honor this request or ignore and and provide a full-state update in the corresponding `Resource` response.

Resource as transferred via the Mesh Configuration Protocol. Each resource is made up of common metadata, and a type-specific resource payload.

Used in: IncrementalMeshConfigResponse, MeshConfigResponse, Resources

• optional Metadata metadata = 1

  Common metadata describing the resource.

• optional google.protobuf.Any body = 2

  The primary payload for the resource.

Resources do not need to include a full snapshot of the tracked resources. Instead they are a diff to the state of a MCP client. Per resource versions allow sources and sinks to track state at the resource granularity. An MCP incremental session is always in the context of a gRPC bidirectional stream. This allows the MCP source to keep track of the state of MCP sink connected to it. In Incremental MCP the nonce field is required and used to pair Resources to an RequestResources ACK or NACK.

Used as request type in: ResourceSink.EstablishResourceStream

Used as response type in: ResourceSource.EstablishResourceStream

• string system_version_info = 1

  The version of the response data (used for debugging).

• string collection = 2

  Type of resource collection that is being requested, e.g. istio/networking/v1alpha3/VirtualService k8s/<apiVersion>/<kind>

• repeated Resource resources = 3

  The response resources wrapped in the common MCP *Resource* message. These are typed resources that match the type url in the RequestResources message. When `incremental` is true, this contains an array of resources to add/update for the specified collection. This modifies the existing collection at the sink When `incremental` is false, this contains the full set of resources for the specified collection. This replaces any previously delivered resources.

• repeated string removed_resources = 4

  Names of resources that have been deleted and to be removed from the MCP sink node. Removed resources for missing resources can be ignored. When `incremental` is true, this contains an array of resource names to remove for the specified collection. This modifies the existing resource collection at the sink. When `incremental` is false, this field should be ignored.

• string nonce = 5

  Required. The nonce provides a way for RequestChange to uniquely reference a RequestResources.

• bool incremental = 6

  This resource response is an incremental update. The source should only send incremental updates if the sink requested them.

Identifies a specific MCP sink node instance. The node identifier is presented to the resource source, which may use this identifier to distinguish per sink configuration for serving. This information is not authoritative. Authoritative identity should come from the underlying transport layer (e.g. rpc credentials).

Used in: IncrementalMeshConfigRequest, MeshConfigRequest, RequestResources

• string id = 1

  An opaque identifier for the MCP node.

• map<string, string> annotations = 2

  Opaque annotations extending the node identifier.