feat: add AgentAPI using DRPC (#10811)

Co-authored-by: Spike Curtis <spike@coder.com>

codersdk/agentsdk/rpc.go

@@ -0,0 +1,68 @@
+package agentsdk
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"net/http/cookiejar"
+
+	"github.com/hashicorp/yamux"
+	"golang.org/x/xerrors"
+	"nhooyr.io/websocket"
+
+	agentproto "github.com/coder/coder/v2/agent/proto"
+	"github.com/coder/coder/v2/codersdk"
+	"github.com/coder/coder/v2/codersdk/drpc"
+)
+
+func (c *Client) RPC(ctx context.Context) (agentproto.DRPCAgentClient, error) {
+	rpcURL, err := c.SDK.URL.Parse("/api/v2/workspaceagents/me/rpc")
+	if err != nil {
+		return nil, xerrors.Errorf("parse url: %w", err)
+	}
+	jar, err := cookiejar.New(nil)
+	if err != nil {
+		return nil, xerrors.Errorf("create cookie jar: %w", err)
+	}
+	jar.SetCookies(rpcURL, []*http.Cookie{{
+		Name:  codersdk.SessionTokenCookie,
+		Value: c.SDK.SessionToken(),
+	}})
+	httpClient := &http.Client{
+		Jar:       jar,
+		Transport: c.SDK.HTTPClient.Transport,
+	}
+	// nolint:bodyclose
+	conn, res, err := websocket.Dial(ctx, rpcURL.String(), &websocket.DialOptions{
+		HTTPClient: httpClient,
+	})
+	if err != nil {
+		if res == nil {
+			return nil, err
+		}
+		return nil, codersdk.ReadBodyAsError(res)
+	}
+
+	ctx, cancelFunc := context.WithCancel(ctx)
+	ctx, wsNetConn := websocketNetConn(ctx, conn, websocket.MessageBinary)
+	pingClosed := pingWebSocket(ctx, c.SDK.Logger(), conn, "RPC")
+
+	nconn := &closeNetConn{
+		Conn: wsNetConn,
+		closeFunc: func() {
+			cancelFunc()
+			_ = conn.Close(websocket.StatusGoingAway, "Listen closed")
+			<-pingClosed
+		},
+	}
+
+	config := yamux.DefaultConfig()
+	config.LogOutput = io.Discard
+	mux, err := yamux.Client(nconn, config)
+	if err != nil {
+		return nil, xerrors.Errorf("create yamux client: %w", err)
+	}
+
+	dconn := drpc.MultiplexedConn(mux)
+	return agentproto.NewDRPCAgentClient(dconn), nil
+}