feat(cli): add trafficgen command for load testing (#7307)

This PR adds a scaletest workspace-traffic command for load testing. This opens a
ReconnectingPTY connection to each scaletest workspace (via coderd) and 
concurrently writes and reads random data to/from the PTY. Payloads are of the
form #${RANDOM_ALPHANUMERIC_STRING}, which essentially drops garbage
comments in the remote shell, and should not result in any commands being executed.

cli/scaletest_test.go

@@ -1,24 +1,30 @@
 package cli_test
 
 import (
+	"bytes"
 	"context"
 	"encoding/json"
 	"os"
 	"path/filepath"
 	"testing"
 
+	"github.com/google/uuid"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
+	"github.com/coder/coder/agent"
 	"github.com/coder/coder/cli/clitest"
 	"github.com/coder/coder/coderd/coderdtest"
 	"github.com/coder/coder/codersdk"
+	"github.com/coder/coder/codersdk/agentsdk"
+	"github.com/coder/coder/provisioner/echo"
+	"github.com/coder/coder/provisionersdk/proto"
 	"github.com/coder/coder/pty/ptytest"
 	"github.com/coder/coder/scaletest/harness"
 	"github.com/coder/coder/testutil"
 )
 
-func TestScaleTest(t *testing.T) {
+func TestScaleTestCreateWorkspaces(t *testing.T) {
 	t.Skipf("This test is flakey. See https://github.com/coder/coder/issues/4942")
 	t.Parallel()
 
@@ -198,3 +204,71 @@ param3: 1
 		require.Len(t, users.Users, 1)
 	})
 }
+
+// This test pretends to stand up a workspace and run a no-op traffic generation test.
+// It's not a real test, but it's useful for debugging.
+// We do not perform any cleanup.
+func TestScaleTestWorkspaceTraffic(t *testing.T) {
+	t.Parallel()
+
+	ctx, cancelFunc := context.WithTimeout(context.Background(), testutil.WaitMedium)
+	defer cancelFunc()
+
+	client := coderdtest.New(t, &coderdtest.Options{IncludeProvisionerDaemon: true})
+	user := coderdtest.CreateFirstUser(t, client)
+
+	authToken := uuid.NewString()
+	version := coderdtest.CreateTemplateVersion(t, client, user.OrganizationID, &echo.Responses{
+		Parse:         echo.ParseComplete,
+		ProvisionPlan: echo.ProvisionComplete,
+		ProvisionApply: []*proto.Provision_Response{{
+			Type: &proto.Provision_Response_Complete{
+				Complete: &proto.Provision_Complete{
+					Resources: []*proto.Resource{{
+						Name: "example",
+						Type: "aws_instance",
+						Agents: []*proto.Agent{{
+							Id:   uuid.NewString(),
+							Name: "agent",
+							Auth: &proto.Agent_Token{
+								Token: authToken,
+							},
+							Apps: []*proto.App{},
+						}},
+					}},
+				},
+			},
+		}},
+	})
+	template := coderdtest.CreateTemplate(t, client, user.OrganizationID, version.ID)
+	coderdtest.AwaitTemplateVersionJob(t, client, version.ID)
+
+	ws := coderdtest.CreateWorkspace(t, client, user.OrganizationID, template.ID, func(cwr *codersdk.CreateWorkspaceRequest) {
+		cwr.Name = "scaletest-test"
+	})
+	coderdtest.AwaitWorkspaceBuildJob(t, client, ws.LatestBuild.ID)
+
+	agentClient := agentsdk.New(client.URL)
+	agentClient.SetSessionToken(authToken)
+	agentCloser := agent.New(agent.Options{
+		Client: agentClient,
+	})
+	t.Cleanup(func() {
+		_ = agentCloser.Close()
+	})
+
+	coderdtest.AwaitWorkspaceAgents(t, client, ws.ID)
+
+	inv, root := clitest.New(t, "scaletest", "workspace-traffic",
+		"--timeout", "1s",
+		"--bytes-per-tick", "1024",
+		"--tick-interval", "100ms",
+	)
+	clitest.SetupConfig(t, client, root)
+	var stdout, stderr bytes.Buffer
+	inv.Stdout = &stdout
+	inv.Stderr = &stderr
+	err := inv.WithContext(ctx).Run()
+	require.NoError(t, err)
+	require.Contains(t, stdout.String(), "Pass:  1")
+}