fix: Start SFTP sessions in user home (working directory)

mafredri · mafredri · commit c280bda78e28 · 2022-10-07T19:49:54.000+03:00
This is a simple fix for #3620 by changing the working directory of `coder agent` at runtime. Since the agent doesn't write files to it's working directory, I can't think of any downsides to this method. It does not, however, exclude that we rewrite the SFTP implementation to use the modernized `RequestServer` sometime in the future. Opted to place this in agent init vs `cli/agent` because of portability of fix, tests don't usually use `cli/agent`. Fixes #3620
diff --git a/agent/agent.go b/agent/agent.go
@@ -378,6 +378,17 @@ func (a *agent) runStartupScript(ctx context.Context, script string) error {
 }
 
 func (a *agent) init(ctx context.Context) {
+	// Change current working directory to the users home
+	// directory so that SFTP connections land there.
+	// https://github.com/coder/coder/issues/3620
+	u, err := user.Current()
+	if err != nil {
+		a.logger.Warn(ctx, "change working directory failed, unable to get current user", slog.Error(err))
+	} else {
+		err = os.Chdir(u.HomeDir)
+		a.logger.Warn(ctx, "change working directory failed", slog.Error(err))
+	}
+
 	a.logger.Info(ctx, "generating host key")
 	// Clients' should ignore the host key when connecting.
 	// The agent needs to authenticate with coderd to SSH,
diff --git a/agent/agent_test.go b/agent/agent_test.go
@@ -10,6 +10,7 @@ import (
 	"net/netip"
 	"os"
 	"os/exec"
+	"os/user"
 	"path/filepath"
 	"runtime"
 	"strconv"
@@ -212,12 +213,17 @@ func TestAgent(t *testing.T) {
 
 	t.Run("SFTP", func(t *testing.T) {
 		t.Parallel()
+		u, err := user.Current()
+		require.NoError(t, err, "get current user")
 		conn, _ := setupAgent(t, codersdk.WorkspaceAgentMetadata{}, 0)
 		sshClient, err := conn.SSHClient()
 		require.NoError(t, err)
 		defer sshClient.Close()
 		client, err := sftp.NewClient(sshClient)
 		require.NoError(t, err)
+		wd, err := client.Getwd()
+		require.NoError(t, err, "get working directory")
+		require.Equal(t, u.HomeDir, wd, "working directory should be home user home")
 		tempFile := filepath.Join(t.TempDir(), "sftp")
 		file, err := client.Create(tempFile)
 		require.NoError(t, err)
