refactor: move api, client, compose packages to pkg

pkg/client/connector/ssh.go

@@ -0,0 +1,88 @@
+package connector
+
+import (
+	"context"
+	"fmt"
+	"github.com/psviderski/uncloud/internal/machine"
+	"github.com/psviderski/uncloud/internal/sshexec"
+	"golang.org/x/crypto/ssh"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/insecure"
+	"net"
+	"strings"
+)
+
+type SSHConnectorConfig struct {
+	User    string
+	Host    string
+	Port    int
+	KeyPath string
+
+	SockPath string
+}
+
+// SSHConnector establishes a connection to the machine API through an SSH tunnel to the machine.
+type SSHConnector struct {
+	config SSHConnectorConfig
+	client *ssh.Client
+}
+
+func NewSSHConnector(cfg *SSHConnectorConfig) *SSHConnector {
+	return &SSHConnector{config: *cfg}
+}
+
+func NewSSHConnectorFromClient(client *ssh.Client) *SSHConnector {
+	return &SSHConnector{client: client}
+}
+
+// TODO: handle context cancelation.
+func (c *SSHConnector) Connect(ctx context.Context) (*grpc.ClientConn, error) {
+	if c.client == nil {
+		// Establish an SSH connection if the SSH client is not provided.
+		if c.config == (SSHConnectorConfig{}) {
+			return nil, fmt.Errorf("SSH connector not configured")
+		}
+		var err error
+		c.client, err = sshexec.Connect(c.config.User, c.config.Host, c.config.Port, c.config.KeyPath)
+		if err != nil {
+			return nil, fmt.Errorf("SSH login to %s@%s:%d: %w", c.config.User, c.config.Host, c.config.Port, err)
+		}
+	}
+
+	sockPath := c.config.SockPath
+	if sockPath == "" {
+		sockPath = machine.DefaultUncloudSockPath
+	}
+	conn, err := grpc.NewClient(
+		"unix://"+sockPath,
+		grpc.WithTransportCredentials(insecure.NewCredentials()),
+		grpc.WithContextDialer(
+			func(ctx context.Context, addr string) (net.Conn, error) {
+				addr = strings.TrimPrefix(addr, "unix://")
+				conn, dErr := c.client.DialContext(ctx, "unix", addr)
+				if dErr != nil {
+					return nil, fmt.Errorf(
+						"connect to machine API socket '%s' through SSH tunnel (is the Uncloud daemon running "+
+							"on the remote machine and does the SSH user '%s' have permissions to access the socket?):"+
+							" %w",
+						addr, c.client.User(), dErr,
+					)
+				}
+				return conn, nil
+			},
+		),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("create machine API client: %w", err)
+	}
+	return conn, nil
+}
+
+func (c *SSHConnector) Close() error {
+	if c.client != nil {
+		err := c.client.Close()
+		c.client = nil
+		return err
+	}
+	return nil
+}