mcp

package
v1.12.0 Latest Latest
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 Go to latest Published: Mar 6, 2026 License: Apache-2.0 Imports: 22 Imported by: 0

Documentation

Overview

Package mcp implements Dynamic Client Registration Protocol (RFC 7591)

Package mcp provides a client for the Model Control Protocol (MCP) that allows the AI plugin to access external tools provided by MCP servers.

The UserClients represents a single user's connection to multiple MCP servers. The Client represents a connection to a single MCP server. The UserClients currently only supports authentication via Mattermost user ID header X-Mattermost-UserID. In the future it will support our OAuth implementation.

The ClientManager manages multiple UserClients, allowing for efficient mangement of connections. It is responsible for creating and closing UserClients as needed.

The organization reflects the need for each user to have their own connection to the MCP server given the design of MCP.

Index

Constants

View Source 
const (
	MMUserIDHeader     = "X-Mattermost-UserID"
	EmbeddedServerName = "Mattermost"
	EmbeddedClientKey  = "embedded://mattermost"
)

Variables

This section is empty.

Functions

func GetRegistrationEndpoint added in v1.4.0 

func GetRegistrationEndpoint(ctx context.Context, httpClient *http.Client, serverURL string) (string, error)

GetRegistrationEndpoint discovers the registration endpoint from server metadata

Types

type AuthorizationServerMetadata added in v1.4.0 

type AuthorizationServerMetadata struct {
	Issuer                 string   `json:"issuer"`
	AuthorizationEndpoint  string   `json:"authorization_endpoint"`
	TokenEndpoint          string   `json:"token_endpoint"`
	ResponseTypesSupported []string `json:"response_types_supported"`
	GrantTypesSupported    []string `json:"grant_types_supported,omitempty"`
	ScopesSupported        []string `json:"scopes_supported,omitempty"`
	RegistrationEndpoint   string   `json:"registration_endpoint,omitempty"`
}

AuthorizationServerMetadata represents the OAuth 2.0 Authorization Server Metadata (RFC 8414)

type CachedTools added in v1.5.0 

type CachedTools struct {
	Tools      map[string]*mcp.Tool `json:"tools"`
	Timestamp  time.Time            `json:"timestamp"`
	ServerURL  string               `json:"server_url"`
	ServerName string               `json:"server_name"`
}

CachedTools represents a cached set of tools for a specific MCP server

type Client added in v1.4.0 

type Client struct {
	// contains filtered or unexported fields
}

Client represents the connection to a single MCP server

func NewClient added in v1.4.0 

func NewClient(ctx context.Context, userID string, serverConfig ServerConfig, log pluginapi.LogService, oauthManager *OAuthManager, httpClient *http.Client, toolsCache *ToolsCache) (*Client, error)

NewClient creates a new MCP client for the given server and user and connects to the specified MCP server

func (*Client) CallTool added in v1.4.0 

func (c *Client) CallTool(ctx context.Context, toolName string, args map[string]any) (string, error)

CallTool calls a tool on this MCP server

func (*Client) CallToolWithMetadata added in v1.6.0 

func (c *Client) CallToolWithMetadata(ctx context.Context, toolName string, args map[string]any, metadata map[string]any) (string, error)

CallToolWithMetadata calls a tool on this MCP server with optional metadata

func (*Client) Close added in v1.4.0 

func (c *Client) Close() error

Close closes the connection to the MCP server

func (*Client) Tools added in v1.4.0 

func (c *Client) Tools() map[string]*mcp.Tool

Tools returns the tools available from this client

type ClientCredentials added in v1.4.0 

type ClientCredentials struct {
	ClientID     string    `json:"clientID"`
	ClientSecret string    `json:"clientSecret"`
	ServerURL    string    `json:"serverURL"`
	CreatedAt    time.Time `json:"createdAt"`
}

type ClientManager 

type ClientManager struct {
	// contains filtered or unexported fields
}

ClientManager manages MCP clients for multiple users

func NewClientManager 

func NewClientManager(config Config, log pluginapi.LogService, pluginAPI *pluginapi.Client, oauthManager *OAuthManager, embeddedServer EmbeddedMCPServer, httpClient *http.Client) *ClientManager

NewClientManager creates a new MCP client manager embeddedServer can be nil if embedded server is not available

func (*ClientManager) Close 

func (m *ClientManager) Close()

Close closes the client manager and all managed clients The client manger should not be used after Close is called

func (*ClientManager) EnsureMCPSessionID added in v1.6.0 

func (m *ClientManager) EnsureMCPSessionID(userID string) (string, error)

EnsureMCPSessionID ensures there is a valid MCP session for the user This is used by both embedded and HTTP MCP servers to get a dedicated session

func (*ClientManager) GetEmbeddedServer added in v1.5.0 

func (m *ClientManager) GetEmbeddedServer() EmbeddedMCPServer

GetEmbeddedServer returns the embedded MCP server instance (may be nil) This method is kept for API compatibility

func (*ClientManager) GetHTTPClient added in v1.7.0 

func (m *ClientManager) GetHTTPClient() *http.Client

GetHTTPClient returns the HTTP client for upstream requests

func (*ClientManager) GetOAuthManager added in v1.4.0 

func (m *ClientManager) GetOAuthManager() *OAuthManager

GetOAuthManager returns the OAuth manager instance

func (*ClientManager) GetToolsCache added in v1.5.0 

func (m *ClientManager) GetToolsCache() *ToolsCache

GetToolsCache returns the tools cache instance

func (*ClientManager) GetToolsForUser 

func (m *ClientManager) GetToolsForUser(userID string) ([]llm.Tool, *Errors)

GetToolsForUser returns the tools available for a specific user, connecting to embedded server if session ID provided

func (*ClientManager) ProcessOAuthCallback added in v1.4.0 

func (m *ClientManager) ProcessOAuthCallback(ctx context.Context, userID, state, code string) (*OAuthSession, error)

ProcessOAuthCallback processes the OAuth callback for a user

func (*ClientManager) ReInit 

func (m *ClientManager) ReInit(config Config, embeddedServer EmbeddedMCPServer)

ReInit re-initializes the client manager with a new configuration and embedded server

type Config 

type Config struct {
	Enabled            bool                 `json:"enabled"`
	EnablePluginServer bool                 `json:"enablePluginServer"`
	Servers            []ServerConfig       `json:"servers"`
	EmbeddedServer     EmbeddedServerConfig `json:"embeddedServer"`
	IdleTimeoutMinutes int                  `json:"idleTimeoutMinutes"`
}

Config contains the configuration for the MCP servers

type EmbeddedMCPServer added in v1.5.0 

type EmbeddedMCPServer interface {
	CreateClientTransport(userID, sessionID string, pluginAPI *pluginapi.Client) (*mcp.InMemoryTransport, error)
}

EmbeddedMCPServer interface for dependency injection

type EmbeddedServerClient added in v1.5.0 

type EmbeddedServerClient struct {
	// contains filtered or unexported fields
}

EmbeddedServerClient handles connections to the embedded MCP server

func NewEmbeddedServerClient added in v1.5.0 

func NewEmbeddedServerClient(server EmbeddedMCPServer, log pluginapi.LogService, pluginAPI *pluginapi.Client) *EmbeddedServerClient

func (*EmbeddedServerClient) CreateClient added in v1.5.0 

func (c *EmbeddedServerClient) CreateClient(ctx context.Context, userID, sessionID string) (*Client, error)

CreateClient creates an embedded MCP client using session ID for authentication If sessionID is empty, creates an unauthenticated client (used for tool discovery)

type EmbeddedServerConfig added in v1.5.0 

type EmbeddedServerConfig struct {
	Enabled bool `json:"enabled"`
}

EmbeddedServerConfig contains configuration for the embedded MCP server

type Errors added in v1.4.0 

type Errors struct {
	ToolAuthErrors []llm.ToolAuthError // Authentication errors users need to resolve
	Errors         []error             // Generic errors (connection, config, etc.)
}

Errors represents a collection of errors from MCP operations.

type KVStore added in v1.5.0 

type KVStore interface {
	Get(key string, o any) error
	Set(key string, value any, options ...pluginapi.KVSetOption) (bool, error)
	Delete(key string) error
	ListKeys(page, count int, options ...pluginapi.ListKeysOption) ([]string, error)
}

KVStore interface for key-value operations

type Logger added in v1.5.0 

type Logger interface {
	Debug(msg string, keyValuePairs ...interface{})
	Info(msg string, keyValuePairs ...interface{})
	Warn(msg string, keyValuePairs ...interface{})
	Error(msg string, keyValuePairs ...interface{})
}

Logger interface for logging operations

type OAuthManager added in v1.4.0 

type OAuthManager struct {
	// contains filtered or unexported fields
}

func NewOAuthManager added in v1.4.0 

func NewOAuthManager(pluginAPI mmapi.Client, callbackURL string, httpClient *http.Client) *OAuthManager

func (*OAuthManager) InitiateOAuthFlow added in v1.4.0 

func (m *OAuthManager) InitiateOAuthFlow(ctx context.Context, userID, serverID, serverURL, metadataURL string) (string, error)

func (*OAuthManager) ProcessCallback added in v1.4.0 

func (m *OAuthManager) ProcessCallback(ctx context.Context, loggedInUserID, state, code string) (*OAuthSession, error)

type OAuthNeededError added in v1.4.0 

type OAuthNeededError struct {
	// contains filtered or unexported fields
}

func (*OAuthNeededError) AuthURL added in v1.4.0 

func (e *OAuthNeededError) AuthURL() string

func (*OAuthNeededError) Error added in v1.4.0 

func (e *OAuthNeededError) Error() string

func (*OAuthNeededError) Unwrap added in v1.4.0 

func (e *OAuthNeededError) Unwrap() error

type OAuthSession added in v1.4.0 

type OAuthSession struct {
	UserID            string    `json:"userID"`
	ServerID          string    `json:"serverID"`
	ServerURL         string    `json:"serverURL"`
	ServerMetadataURL string    `json:"serverMetadataURL"`
	CodeVerifier      string    `json:"codeVerifier"`
	State             string    `json:"state"`
	CreatedAt         time.Time `json:"createdAt"`
}

type ProtectedResourceMetadata added in v1.4.0 

type ProtectedResourceMetadata struct {
	Resource             string   `json:"resource"`
	AuthorizationServers []string `json:"authorization_servers"`
}

ProtectedResourceMetadata represents the OAuth 2.0 Protected Resource Metadata (RFC 9728)

type RegistrationError added in v1.4.0 

type RegistrationError struct {
	ErrorCode        string         `json:"error"`
	ErrorDescription string         `json:"error_description,omitempty"`
	HTTPStatusCode   int            `json:"-"`
	HTTPResponse     *http.Response `json:"-"`
}

RegistrationError represents an error response per RFC 7591

func (*RegistrationError) Error added in v1.4.0 

func (e *RegistrationError) Error() string

type RegistrationRequest added in v1.4.0 

type RegistrationRequest struct {
	// Required fields
	RedirectURIs []string `json:"redirect_uris"`

	// Optional fields commonly used
	TokenEndpointAuthMethod string   `json:"token_endpoint_auth_method,omitempty"`
	GrantTypes              []string `json:"grant_types,omitempty"`
	ResponseTypes           []string `json:"response_types,omitempty"`
	ClientName              string   `json:"client_name,omitempty"`
	Scope                   string   `json:"scope,omitempty"`
	Contacts                []string `json:"contacts,omitempty"`

	// Additional optional fields can be added as needed
	ClientURI string `json:"client_uri,omitempty"`
	LogoURI   string `json:"logo_uri,omitempty"`
	ToSURI    string `json:"tos_uri,omitempty"`
	PolicyURI string `json:"policy_uri,omitempty"`
}

RegistrationRequest represents a client registration request per RFC 7591

func DefaultRegistrationRequest added in v1.4.0 

func DefaultRegistrationRequest(redirectURI, clientName string) *RegistrationRequest

DefaultRegistrationRequest creates a default registration request for MCP clients

type RegistrationResponse added in v1.4.0 

type RegistrationResponse struct {
	// Required fields
	ClientID string `json:"client_id"`

	// Optional fields
	ClientSecret          string `json:"client_secret,omitempty"`
	ClientIDIssuedAt      *int64 `json:"client_id_issued_at,omitempty"`
	ClientSecretExpiresAt *int64 `json:"client_secret_expires_at,omitempty"`

	// Echo back the registration metadata
	RedirectURIs            []string `json:"redirect_uris,omitempty"`
	TokenEndpointAuthMethod string   `json:"token_endpoint_auth_method,omitempty"`
	GrantTypes              []string `json:"grant_types,omitempty"`
	ResponseTypes           []string `json:"response_types,omitempty"`
	ClientName              string   `json:"client_name,omitempty"`
	Scope                   string   `json:"scope,omitempty"`
	Contacts                []string `json:"contacts,omitempty"`
	ClientURI               string   `json:"client_uri,omitempty"`
	LogoURI                 string   `json:"logo_uri,omitempty"`
	ToSURI                  string   `json:"tos_uri,omitempty"`
	PolicyURI               string   `json:"policy_uri,omitempty"`
}

RegistrationResponse represents the server's response per RFC 7591

func DiscoverAndRegisterClient added in v1.4.0 

func DiscoverAndRegisterClient(ctx context.Context, httpClient *http.Client, serverURL, callbackURL, clientID, initialAccessToken string) (*RegistrationResponse, error)

DiscoverAndRegisterClient performs the complete client registration flow: 1. Discovers the registration endpoint from server metadata 2. Creates a default registration request 3. Registers the client with the server

func RegisterClient added in v1.4.0 

func RegisterClient(ctx context.Context, httpClient *http.Client, registrationEndpoint string, request *RegistrationRequest, initialAccessToken string) (*RegistrationResponse, error)

RegisterClient performs dynamic client registration per RFC 7591

type ServerConfig 

type ServerConfig struct {
	Name    string            `json:"name"`
	Enabled bool              `json:"enabled"`
	BaseURL string            `json:"baseURL"`
	Headers map[string]string `json:"headers,omitempty"`
}

ServerConfig contains the configuration for a single MCP server

type ToolInfo added in v1.4.0 

type ToolInfo struct {
	Name        string `json:"name"`
	Description string `json:"description"`
	InputSchema any    `json:"inputSchema"`
}

ToolInfo represents a tool's metadata for discovery purposes

func DiscoverEmbeddedServerTools added in v1.5.0 

func DiscoverEmbeddedServerTools(
	ctx context.Context,
	userID string,
	sessionID string,
	embeddedServerConfig EmbeddedServerConfig,
	embeddedServer EmbeddedMCPServer,
	log pluginapi.LogService,
	pluginAPI *pluginapi.Client,
) ([]ToolInfo, error)

DiscoverEmbeddedServerTools creates a temporary connection to an embedded MCP server and discovers its tools

func DiscoverRemoteServerTools added in v1.5.0 

func DiscoverRemoteServerTools(
	ctx context.Context,
	userID string,
	serverConfig ServerConfig,
	log pluginapi.LogService,
	oauthManger *OAuthManager,
	httpClient *http.Client,
	toolsCache *ToolsCache,
) ([]ToolInfo, error)

DiscoverRemoteServerTools creates a temporary connection to a remote MCP server and discovers its tools

type ToolsCache added in v1.5.0 

type ToolsCache struct {
	// contains filtered or unexported fields
}

ToolsCache manages the global cache of MCP tools across all users It uses the KV store directly for HA mode compatibility

func NewToolsCache added in v1.5.0 

func NewToolsCache(kvAPI KVStore, log Logger) *ToolsCache

NewToolsCache creates a new ToolsCache instance

func (*ToolsCache) ClearAll added in v1.5.0 

func (tc *ToolsCache) ClearAll() (int, error)

ClearAll removes all cached tools from KV store

func (*ToolsCache) GetTools added in v1.5.0 

func (tc *ToolsCache) GetTools(serverID string) map[string]*mcp.Tool

GetTools retrieves cached tools for a server, returns nil if missing

func (*ToolsCache) InvalidateServer added in v1.5.0 

func (tc *ToolsCache) InvalidateServer(serverID string) error

InvalidateServer removes a server's cache entry from KV store Delete returns no error for non-existent keys, only errors on actual failures

func (*ToolsCache) SetTools added in v1.5.0 

func (tc *ToolsCache) SetTools(serverID string, serverName string, serverURL string, tools map[string]*mcp.Tool, timestamp time.Time) error

SetTools updates the cache for a server and persists to KV store

type UserClients added in v1.4.0 

type UserClients struct {
	// contains filtered or unexported fields
}

UserClients represents a per-user MCP client with multiple server connections

func NewUserClients added in v1.4.0 

func NewUserClients(userID string, log pluginapi.LogService, oauthManager *OAuthManager, httpClient *http.Client, toolsCache *ToolsCache) *UserClients

func (*UserClients) Close added in v1.4.0 

func (c *UserClients) Close()

Close closes all server connections for a user client

func (*UserClients) ConnectToEmbeddedServerIfAvailable added in v1.5.0 

func (c *UserClients) ConnectToEmbeddedServerIfAvailable(sessionID string, embeddedClient *EmbeddedServerClient, embeddedConfig EmbeddedServerConfig) error

ConnectToEmbeddedServerIfAvailable connects to the embedded server if session ID is provided

func (*UserClients) ConnectToRemoteServers added in v1.5.0 

func (c *UserClients) ConnectToRemoteServers(servers []ServerConfig) *Errors

ConnectToRemoteServers initializes connections to remote MCP servers

func (*UserClients) GetTools added in v1.4.0 

func (c *UserClients) GetTools() []llm.Tool

GetTools returns the tools available from the clients

Source Files

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