cli/internal/codespaces/grpc/client.go
2022-10-11 09:14:23 -04:00

145 lines
4.2 KiB
Go

package grpc
// gRPC client implementation to be able to connect to the gRPC server and perform the following operations:
// - Start a remote JupyterLab server
import (
"context"
"fmt"
"net"
"strconv"
"time"
"github.com/cli/cli/v2/internal/codespaces/grpc/jupyter"
"github.com/cli/cli/v2/pkg/liveshare"
"golang.org/x/crypto/ssh"
"google.golang.org/grpc"
"google.golang.org/grpc/credentials/insecure"
"google.golang.org/grpc/metadata"
)
const (
ConnectionTimeout = 5 * time.Second
RequestTimeout = 30 * time.Second
)
const (
codespacesInternalPort = 16634
codespacesInternalSessionName = "CodespacesInternal"
)
type Client struct {
conn *grpc.ClientConn
token string
listener net.Listener
jupyterClient jupyter.JupyterServerHostClient
cancelPF context.CancelFunc
}
type liveshareSession interface {
KeepAlive(string)
OpenStreamingChannel(context.Context, liveshare.ChannelID) (ssh.Channel, error)
StartSharing(context.Context, string, int) (liveshare.ChannelID, error)
}
// Finds a free port to listen on and creates a new gRPC client that connects to that port
func Connect(ctx context.Context, session liveshareSession, token string) (*Client, error) {
listener, err := net.Listen("tcp", fmt.Sprintf("127.0.0.1:%d", 0))
if err != nil {
return nil, fmt.Errorf("failed to listen to local port over tcp: %w", err)
}
localAddress := fmt.Sprintf("127.0.0.1:%d", listener.Addr().(*net.TCPAddr).Port)
client := &Client{
token: token,
listener: listener,
}
// Create a cancelable context to be able to cancel background tasks
// if we encounter an error while connecting to the gRPC server
connectctx, cancel := context.WithCancel(context.Background())
defer func() {
if err != nil {
cancel()
}
}()
ch := make(chan error, 2) // Buffered channel to ensure we don't block on the goroutine
// Ensure we close the port forwarder if we encounter an error
// or once the gRPC connection is closed. pfcancel is retained
// to close the PF whenever we close the gRPC connection.
pfctx, pfcancel := context.WithCancel(connectctx)
client.cancelPF = pfcancel
// Tunnel the remote gRPC server port to the local port
go func() {
fwd := liveshare.NewPortForwarder(session, codespacesInternalSessionName, codespacesInternalPort, true)
ch <- fwd.ForwardToListener(pfctx, listener)
}()
var conn *grpc.ClientConn
go func() {
// Attempt to connect to the port
opts := []grpc.DialOption{
grpc.WithTransportCredentials(insecure.NewCredentials()),
grpc.WithBlock(),
}
conn, err = grpc.DialContext(connectctx, localAddress, opts...)
ch <- err // nil if we successfully connected
}()
// Wait for the connection to be established or for the context to be cancelled
select {
case <-ctx.Done():
return nil, ctx.Err()
case err := <-ch:
if err != nil {
return nil, err
}
}
client.conn = conn
client.jupyterClient = jupyter.NewJupyterServerHostClient(conn)
return client, nil
}
// Closes the gRPC connection
func (g *Client) Close() error {
g.cancelPF()
// Closing the local listener effectively closes the gRPC connection
if err := g.listener.Close(); err != nil {
g.conn.Close() // If we fail to close the listener, explicitly close the gRPC connection and ignore any error
return fmt.Errorf("failed to close local tcp port listener: %w", err)
}
return nil
}
// Appends the authentication token to the gRPC context
func (g *Client) appendMetadata(ctx context.Context) context.Context {
return metadata.AppendToOutgoingContext(ctx, "Authorization", "Bearer "+g.token)
}
// Starts a remote JupyterLab server to allow the user to connect to the codespace via JupyterLab in their browser
func (g *Client) StartJupyterServer(ctx context.Context) (port int, serverUrl string, err error) {
ctx = g.appendMetadata(ctx)
response, err := g.jupyterClient.GetRunningServer(ctx, &jupyter.GetRunningServerRequest{})
if err != nil {
return 0, "", fmt.Errorf("failed to invoke JupyterLab RPC: %w", err)
}
if !response.Result {
return 0, "", fmt.Errorf("failed to start JupyterLab: %s", response.Message)
}
port, err = strconv.Atoi(response.Port)
if err != nil {
return 0, "", fmt.Errorf("failed to parse JupyterLab port: %w", err)
}
return port, response.ServerUrl, err
}