--- title: istio.mcp.v1alpha1 layout: protoc-gen-docs generator: protoc-gen-docs number_of_entries: 9 ---

This package defines the common, core types used by the Mesh Configuration Protocol.

Services

AggregatedMeshConfigService

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

rpc StreamAggregatedResources(MeshConfigRequest) returns (MeshConfigResponse)

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.

rpc IncrementalAggregatedResources(IncrementalMeshConfigRequest) returns (IncrementalMeshConfigResponse)

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

Types

Client

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

Field Type Description
id string

An opaque identifier for the MCP client.

metadata google.protobuf.Struct

Opaque metadata extending the client identifier.

Envelope

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

Field Type Description
metadata Metadata

Common metadata describing the resource.

resource google.protobuf.Any

The resource itself.

IncrementalMeshConfigRequest

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 responsenonce is set to the nonce value in the Response. ACK or NACK is determined by the absence or presence of errordetail.

Field Type Description
client Client

The client making the request.

typeUrl string

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

initialResourceVersions map<string, string>

When the IncrementalMeshConfigRequest is the first in a stream, the initialresourceversions must be populated. Otherwise, initialresourceversions 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.

responseNonce string

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

errorDetail google.rpc.Status

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.

IncrementalMeshConfigResponse

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 systemversioninfo is present for debugging purposes only.

Field Type Description
systemVersionInfo string

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

envelopes Envelope[]

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

removedResources string[]

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

nonce string

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

MeshConfigRequest

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

Field Type Description
versionInfo string

The versioninfo provided in the request messages will be the versioninfo 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.

client Client

The client making the request.

typeUrl string

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

responseNonce string

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.

errorDetail google.rpc.Status

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.

MeshConfigResponse

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

Field Type Description
versionInfo string

The version of the response data.

envelopes Envelope[]

The response resources wrapped in the common MCP Envelope message.

typeUrl string

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

nonce string

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.

Metadata

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

Field Type Description
name string

The name of the resource. It is unique within the context of a resource type and the origin server of the resource. The resource type is identified by the TypeUrl of the resource field of the Envelope message.

createTime google.protobuf.Timestamp

The creation timestamp of the resource.

version string

The resource level version. It allows MCP to track the state of individual resources.

google.rpc.Status

The Status type defines a logical error model that is suitable for different programming environments, including REST APIs and RPC APIs. It is used by gRPC. The error model is designed to be:

Overview

The Status message contains three pieces of data: error code, error message, and error details. The error code should be an enum value of google.rpc.Code, but it may accept additional error codes if needed. The error message should be a developer-facing English message that helps developers understand and resolve the error. If a localized user-facing error message is needed, put the localized message in the error details or localize it in the client. The optional error details may contain arbitrary information about the error. There is a predefined set of error detail types in the package google.rpc that can be used for common error conditions.

Language mapping

The Status message is the logical representation of the error model, but it is not necessarily the actual wire format. When the Status message is exposed in different client libraries and different wire protocols, it can be mapped differently. For example, it will likely be mapped to some exceptions in Java, but more likely mapped to some error codes in C.

Other uses

The error model and the Status message can be used in a variety of environments, either with or without APIs, to provide a consistent developer experience across different environments.

Example uses of this error model include:

Field Type Description
code int32

The status code, which should be an enum value of google.rpc.Code.

message string

A developer-facing error message, which should be in English. Any user-facing error message should be localized and sent in the google.rpc.Status.details field, or localized by the client.

details google.protobuf.Any[]

A list of messages that carry the error details. There is a common set of message types for APIs to use.