fix: use screen for reconnecting terminal sessions on Linux if available (#8640)

* Add screen backend for reconnecting ptys

The screen portion is a port from wsep.  There is an interface that lets
you choose between screen and the previous method.  By default it will
choose screen if it is installed but this can be overidden (mostly for
tests).

The tests use a scanner instead of a reader now because the reader will
loop infinitely at the end of a stream.

Replace /bin/bash with bash since bash is not always in /bin.

* Remove connection_id from reconnecting PTY logger

This serves multiple connections so it makes no sense to scope it to a
single connection.

Also lets us use "connection_id" when logging write errors instead of
"other_conn_id".

* Use PATH to test buffered reconnecting pty

coderd/workspaceapps/apptest/apptest.go

@@ -12,6 +12,7 @@ import (
 	"net/http/httputil"
 	"net/url"
 	"path"
+	"regexp"
 	"runtime"
 	"strconv"
 	"strings"
@@ -30,6 +31,10 @@ import (
 	"github.com/coder/coder/testutil"
 )
 
+const ansi = "[\u001B\u009B][[\\]()#;?]*(?:(?:(?:[a-zA-Z\\d]*(?:;[a-zA-Z\\d]*)*)?\u0007)|(?:(?:\\d{1,4}(?:;\\d{0,4})*)?[\\dA-PRZcf-ntqry=><~]))"
+
+var re = regexp.MustCompile(ansi)
+
 // Run runs the entire workspace app test suite against deployments minted
 // by the provided factory.
 //
@@ -51,23 +56,8 @@ func Run(t *testing.T, appHostIsPrimary bool, factory DeploymentFactory) {
 			t.Skip("ConPTY appears to be inconsistent on Windows.")
 		}
 
-		expectLine := func(t *testing.T, r *bufio.Reader, matcher func(string) bool) {
-			for {
-				line, err := r.ReadString('\n')
-				require.NoError(t, err)
-				if matcher(line) {
-					break
-				}
-			}
-		}
-		matchEchoCommand := func(line string) bool {
-			return strings.Contains(line, "echo test")
-		}
-		matchEchoOutput := func(line string) bool {
-			return strings.Contains(line, "test") && !strings.Contains(line, "echo")
-		}
-
 		t.Run("OK", func(t *testing.T) {
+			t.Parallel()
 			appDetails := setupProxyTest(t, nil)
 
 			ctx, cancel := context.WithTimeout(context.Background(), testutil.WaitLong)
@@ -76,40 +66,13 @@ func Run(t *testing.T, appHostIsPrimary bool, factory DeploymentFactory) {
 			// Run the test against the path app hostname since that's where the
 			// reconnecting-pty proxy server we want to test is mounted.
 			client := appDetails.AppClient(t)
-			conn, err := client.WorkspaceAgentReconnectingPTY(ctx, codersdk.WorkspaceAgentReconnectingPTYOpts{
+			testReconnectingPTY(ctx, t, client, codersdk.WorkspaceAgentReconnectingPTYOpts{
 				AgentID:   appDetails.Agent.ID,
 				Reconnect: uuid.New(),
 				Height:    80,
 				Width:     80,
-				Command:   "/bin/bash",
+				Command:   "bash",
 			})
-			require.NoError(t, err)
-			defer conn.Close()
-
-			// First attempt to resize the TTY.
-			// The websocket will close if it fails!
-			data, err := json.Marshal(codersdk.ReconnectingPTYRequest{
-				Height: 250,
-				Width:  250,
-			})
-			require.NoError(t, err)
-			_, err = conn.Write(data)
-			require.NoError(t, err)
-			bufRead := bufio.NewReader(conn)
-
-			// Brief pause to reduce the likelihood that we send keystrokes while
-			// the shell is simultaneously sending a prompt.
-			time.Sleep(100 * time.Millisecond)
-
-			data, err = json.Marshal(codersdk.ReconnectingPTYRequest{
-				Data: "echo test\r\n",
-			})
-			require.NoError(t, err)
-			_, err = conn.Write(data)
-			require.NoError(t, err)
-
-			expectLine(t, bufRead, matchEchoCommand)
-			expectLine(t, bufRead, matchEchoOutput)
 		})
 
 		t.Run("SignedTokenQueryParameter", func(t *testing.T) {
@@ -137,41 +100,14 @@ func Run(t *testing.T, appHostIsPrimary bool, factory DeploymentFactory) {
 
 			// Make an unauthenticated client.
 			unauthedAppClient := codersdk.New(appDetails.AppClient(t).URL)
-			conn, err := unauthedAppClient.WorkspaceAgentReconnectingPTY(ctx, codersdk.WorkspaceAgentReconnectingPTYOpts{
+			testReconnectingPTY(ctx, t, unauthedAppClient, codersdk.WorkspaceAgentReconnectingPTYOpts{
 				AgentID:     appDetails.Agent.ID,
 				Reconnect:   uuid.New(),
 				Height:      80,
 				Width:       80,
-				Command:     "/bin/bash",
+				Command:     "bash",
 				SignedToken: issueRes.SignedToken,
 			})
-			require.NoError(t, err)
-			defer conn.Close()
-
-			// First attempt to resize the TTY.
-			// The websocket will close if it fails!
-			data, err := json.Marshal(codersdk.ReconnectingPTYRequest{
-				Height: 250,
-				Width:  250,
-			})
-			require.NoError(t, err)
-			_, err = conn.Write(data)
-			require.NoError(t, err)
-			bufRead := bufio.NewReader(conn)
-
-			// Brief pause to reduce the likelihood that we send keystrokes while
-			// the shell is simultaneously sending a prompt.
-			time.Sleep(100 * time.Millisecond)
-
-			data, err = json.Marshal(codersdk.ReconnectingPTYRequest{
-				Data: "echo test\r\n",
-			})
-			require.NoError(t, err)
-			_, err = conn.Write(data)
-			require.NoError(t, err)
-
-			expectLine(t, bufRead, matchEchoCommand)
-			expectLine(t, bufRead, matchEchoOutput)
 		})
 	})
 
@@ -1407,3 +1343,75 @@ func Run(t *testing.T, appHostIsPrimary bool, factory DeploymentFactory) {
 		require.Equal(t, []string{"baz"}, resp.Header.Values("X-Foobar"))
 	})
 }
+
+func testReconnectingPTY(ctx context.Context, t *testing.T, client *codersdk.Client, opts codersdk.WorkspaceAgentReconnectingPTYOpts) {
+	hasLine := func(scanner *bufio.Scanner, matcher func(string) bool) bool {
+		for scanner.Scan() {
+			line := scanner.Text()
+			t.Logf("bash tty stdout = %s", re.ReplaceAllString(line, ""))
+			if matcher(line) {
+				return true
+			}
+		}
+		return false
+	}
+	matchEchoCommand := func(line string) bool {
+		return strings.Contains(line, "echo test")
+	}
+	matchEchoOutput := func(line string) bool {
+		return strings.Contains(line, "test") && !strings.Contains(line, "echo")
+	}
+	matchExitCommand := func(line string) bool {
+		return strings.Contains(line, "exit")
+	}
+	matchExitOutput := func(line string) bool {
+		return strings.Contains(line, "exit") || strings.Contains(line, "logout")
+	}
+
+	conn, err := client.WorkspaceAgentReconnectingPTY(ctx, opts)
+	require.NoError(t, err)
+	defer conn.Close()
+
+	// First attempt to resize the TTY.
+	// The websocket will close if it fails!
+	data, err := json.Marshal(codersdk.ReconnectingPTYRequest{
+		Height: 250,
+		Width:  250,
+	})
+	require.NoError(t, err)
+	_, err = conn.Write(data)
+	require.NoError(t, err)
+	scanner := bufio.NewScanner(conn)
+
+	// Brief pause to reduce the likelihood that we send keystrokes while
+	// the shell is simultaneously sending a prompt.
+	time.Sleep(100 * time.Millisecond)
+
+	data, err = json.Marshal(codersdk.ReconnectingPTYRequest{
+		Data: "echo test\r\n",
+	})
+	require.NoError(t, err)
+	_, err = conn.Write(data)
+	require.NoError(t, err)
+
+	require.True(t, hasLine(scanner, matchEchoCommand), "find echo command")
+	require.True(t, hasLine(scanner, matchEchoOutput), "find echo output")
+
+	// Exit should cause the connection to close.
+	data, err = json.Marshal(codersdk.ReconnectingPTYRequest{
+		Data: "exit\r\n",
+	})
+	require.NoError(t, err)
+	_, err = conn.Write(data)
+	require.NoError(t, err)
+
+	// Once for the input and again for the output.
+	require.True(t, hasLine(scanner, matchExitCommand), "find exit command")
+	require.True(t, hasLine(scanner, matchExitOutput), "find exit output")
+
+	// Ensure the connection closes.
+	for scanner.Scan() {
+		line := scanner.Text()
+		t.Logf("bash tty stdout = %s", re.ReplaceAllString(line, ""))
+	}
+}