fix: avoid returning 500 on apps when workspace stopped (#11656)

coderd/workspaceapps/apptest/apptest.go

@@ -26,6 +26,7 @@ import (
 	"golang.org/x/xerrors"
 
 	"github.com/coder/coder/v2/coderd/coderdtest"
+	"github.com/coder/coder/v2/coderd/database"
 	"github.com/coder/coder/v2/coderd/rbac"
 	"github.com/coder/coder/v2/coderd/workspaceapps"
 	"github.com/coder/coder/v2/codersdk"
@@ -1484,6 +1485,24 @@ func Run(t *testing.T, appHostIsPrimary bool, factory DeploymentFactory) {
 		assert.Equal(t, "test-app-owner", stats[0].SlugOrPort)
 		assert.Equal(t, 1, stats[0].Requests)
 	})
+
+	t.Run("WorkspaceOffline", func(t *testing.T) {
+		t.Parallel()
+
+		appDetails := setupProxyTest(t, nil)
+
+		ctx, cancel := context.WithTimeout(context.Background(), testutil.WaitLong)
+		defer cancel()
+
+		_ = coderdtest.MustTransitionWorkspace(t, appDetails.SDKClient, appDetails.Workspace.ID, database.WorkspaceTransitionStart, database.WorkspaceTransitionStop)
+
+		u := appDetails.PathAppURL(appDetails.Apps.Owner)
+		resp, err := appDetails.AppClient(t).Request(ctx, http.MethodGet, u.String(), nil)
+		require.NoError(t, err)
+		_ = resp.Body.Close()
+		require.Equal(t, http.StatusBadRequest, resp.StatusCode)
+		require.Equal(t, "text/html; charset=utf-8", resp.Header.Get("Content-Type"))
+	})
 }
 
 type fakeStatsReporter struct {

coderd/workspaceapps/db.go

@@ -103,6 +103,9 @@ func (p *DBTokenProvider) Issue(ctx context.Context, rw http.ResponseWriter, r *
 	if xerrors.Is(err, sql.ErrNoRows) {
 		WriteWorkspaceApp404(p.Logger, p.DashboardURL, rw, r, &appReq, nil, err.Error())
 		return nil, "", false
+	} else if xerrors.Is(err, errWorkspaceStopped) {
+		WriteWorkspaceOffline(p.Logger, p.DashboardURL, rw, r, &appReq)
+		return nil, "", false
 	} else if err != nil {
 		WriteWorkspaceApp500(p.Logger, p.DashboardURL, rw, r, &appReq, err, "get app details from database")
 		return nil, "", false

coderd/workspaceapps/errors.go

@@ -1,10 +1,12 @@
 package workspaceapps
 
 import (
+	"fmt"
 	"net/http"
 	"net/url"
 
 	"cdr.dev/slog"
+	"github.com/coder/coder/v2/codersdk"
 	"github.com/coder/coder/v2/site"
 )
 
@@ -90,3 +92,28 @@ func WriteWorkspaceAppOffline(log slog.Logger, accessURL *url.URL, rw http.Respo
 		DashboardURL: accessURL.String(),
 	})
 }
+
+// WriteWorkspaceOffline writes a HTML 400 error page for a workspace app. If
+// appReq is not nil, it will be used to log the request details at debug level.
+func WriteWorkspaceOffline(log slog.Logger, accessURL *url.URL, rw http.ResponseWriter, r *http.Request, appReq *Request) {
+	if appReq != nil {
+		slog.Helper()
+		log.Debug(r.Context(),
+			"workspace app unavailable: workspace stopped",
+			slog.F("username_or_id", appReq.UsernameOrID),
+			slog.F("workspace_and_agent", appReq.WorkspaceAndAgent),
+			slog.F("workspace_name_or_id", appReq.WorkspaceNameOrID),
+			slog.F("agent_name_or_id", appReq.AgentNameOrID),
+			slog.F("app_slug_or_port", appReq.AppSlugOrPort),
+			slog.F("hostname_prefix", appReq.Prefix),
+		)
+	}
+
+	site.RenderStaticErrorPage(rw, r, site.ErrorPageData{
+		Status:       http.StatusBadRequest,
+		Title:        "Workspace Offline",
+		Description:  fmt.Sprintf("Last workspace transition was to the %q state. Start the workspace to access its applications.", codersdk.WorkspaceTransitionStop),
+		RetryEnabled: false,
+		DashboardURL: accessURL.String(),
+	})
+}

coderd/workspaceapps/request.go

@@ -17,6 +17,8 @@ import (
 	"github.com/coder/coder/v2/codersdk"
 )
 
+var errWorkspaceStopped = xerrors.New("stopped workspace")
+
 type AccessMethod string
 
 const (
@@ -260,10 +262,17 @@ func (r Request) getDatabase(ctx context.Context, db database.Store) (*databaseR
 	if err != nil {
 		return nil, xerrors.Errorf("get workspace agents: %w", err)
 	}
+	build, err := db.GetLatestWorkspaceBuildByWorkspaceID(ctx, workspace.ID)
+	if err != nil {
+		return nil, xerrors.Errorf("get latest workspace build: %w", err)
+	}
+	if build.Transition == database.WorkspaceTransitionStop {
+		return nil, errWorkspaceStopped
+	}
 	if len(agents) == 0 {
 		// TODO(@deansheather): return a 404 if there are no agents in the
 		// workspace, requires a different error type.
-		return nil, xerrors.New("no agents in workspace")
+		return nil, xerrors.Errorf("no agents in workspace: %w", sql.ErrNoRows)
 	}
 
 	// Get workspace apps.

site/src/pages/TerminalPage/TerminalPage.tsx

@@ -191,7 +191,8 @@ const TerminalPage: FC = () => {
       return;
     } else if (!workspaceAgent) {
       terminal.writeln(
-        Language.workspaceAgentErrorMessagePrefix + "no agent found with ID",
+        Language.workspaceAgentErrorMessagePrefix +
+          "no agent found with ID, is the workspace started?",
       );
       return;
     }