Daily Active User Metrics (#3735)

* agent: add StatsReporter

* Stabilize protoc

coderd/workspaceagents.go

@@ -9,6 +9,7 @@ import (
 	"net"
 	"net/http"
 	"net/netip"
+	"reflect"
 	"strconv"
 	"strings"
 	"time"
@@ -18,6 +19,7 @@ import (
 	"golang.org/x/mod/semver"
 	"golang.org/x/xerrors"
 	"nhooyr.io/websocket"
+	"nhooyr.io/websocket/wsjson"
 	"tailscale.com/tailcfg"
 
 	"cdr.dev/slog"
@@ -745,6 +747,130 @@ func convertWorkspaceAgent(derpMap *tailcfg.DERPMap, coordinator *tailnet.Coordi
 
 	return workspaceAgent, nil
 }
+func (api *API) workspaceAgentReportStats(rw http.ResponseWriter, r *http.Request) {
+	api.websocketWaitMutex.Lock()
+	api.websocketWaitGroup.Add(1)
+	api.websocketWaitMutex.Unlock()
+	defer api.websocketWaitGroup.Done()
+
+	workspaceAgent := httpmw.WorkspaceAgent(r)
+	resource, err := api.Database.GetWorkspaceResourceByID(r.Context(), workspaceAgent.ResourceID)
+	if err != nil {
+		httpapi.Write(rw, http.StatusBadRequest, codersdk.Response{
+			Message: "Failed to get workspace resource.",
+			Detail:  err.Error(),
+		})
+		return
+	}
+
+	build, err := api.Database.GetWorkspaceBuildByJobID(r.Context(), resource.JobID)
+	if err != nil {
+		httpapi.Write(rw, http.StatusBadRequest, codersdk.Response{
+			Message: "Failed to get build.",
+			Detail:  err.Error(),
+		})
+		return
+	}
+
+	workspace, err := api.Database.GetWorkspaceByID(r.Context(), build.WorkspaceID)
+	if err != nil {
+		httpapi.Write(rw, http.StatusBadRequest, codersdk.Response{
+			Message: "Failed to get workspace.",
+			Detail:  err.Error(),
+		})
+		return
+	}
+
+	conn, err := websocket.Accept(rw, r, &websocket.AcceptOptions{
+		CompressionMode: websocket.CompressionDisabled,
+	})
+	if err != nil {
+		httpapi.Write(rw, http.StatusBadRequest, codersdk.Response{
+			Message: "Failed to accept websocket.",
+			Detail:  err.Error(),
+		})
+		return
+	}
+	defer conn.Close(websocket.StatusAbnormalClosure, "")
+
+	// Allow overriding the stat interval for debugging and testing purposes.
+	ctx := r.Context()
+	timer := time.NewTicker(api.AgentStatsRefreshInterval)
+	var lastReport codersdk.AgentStatsReportResponse
+	for {
+		err := wsjson.Write(ctx, conn, codersdk.AgentStatsReportRequest{})
+		if err != nil {
+			httpapi.Write(rw, http.StatusBadRequest, codersdk.Response{
+				Message: "Failed to write report request.",
+				Detail:  err.Error(),
+			})
+			return
+		}
+		var rep codersdk.AgentStatsReportResponse
+
+		err = wsjson.Read(ctx, conn, &rep)
+		if err != nil {
+			httpapi.Write(rw, http.StatusBadRequest, codersdk.Response{
+				Message: "Failed to read report response.",
+				Detail:  err.Error(),
+			})
+			return
+		}
+
+		repJSON, err := json.Marshal(rep)
+		if err != nil {
+			httpapi.Write(rw, http.StatusBadRequest, codersdk.Response{
+				Message: "Failed to marshal stat json.",
+				Detail:  err.Error(),
+			})
+			return
+		}
+
+		// Avoid inserting duplicate rows to preserve DB space.
+		// We will see duplicate reports when on idle connections
+		// (e.g. web terminal left open) or when there are no connections at
+		// all.
+		var insert = !reflect.DeepEqual(lastReport, rep)
+
+		api.Logger.Debug(ctx, "read stats report",
+			slog.F("interval", api.AgentStatsRefreshInterval),
+			slog.F("agent", workspaceAgent.ID),
+			slog.F("resource", resource.ID),
+			slog.F("workspace", workspace.ID),
+			slog.F("insert", insert),
+			slog.F("payload", rep),
+		)
+
+		if insert {
+			lastReport = rep
+
+			_, err = api.Database.InsertAgentStat(ctx, database.InsertAgentStatParams{
+				ID:          uuid.New(),
+				CreatedAt:   time.Now(),
+				AgentID:     workspaceAgent.ID,
+				WorkspaceID: build.WorkspaceID,
+				UserID:      workspace.OwnerID,
+				TemplateID:  workspace.TemplateID,
+				Payload:     json.RawMessage(repJSON),
+			})
+			if err != nil {
+				httpapi.Write(rw, http.StatusBadRequest, codersdk.Response{
+					Message: "Failed to insert agent stat.",
+					Detail:  err.Error(),
+				})
+				return
+			}
+		}
+
+		select {
+		case <-timer.C:
+			continue
+		case <-ctx.Done():
+			conn.Close(websocket.StatusNormalClosure, "")
+			return
+		}
+	}
+}
 
 // wsNetConn wraps net.Conn created by websocket.NetConn(). Cancel func
 // is called if a read or write error is encountered.