feat: Add workspace metrics export to Prometheus (#3421)

This adds workspace totals indexed by status. It could be any
codersdk.ProvisionerJobStatus.

cli/server.go

@@ -402,11 +402,17 @@ func server() *cobra.Command {
 			}
 			if promEnabled {
 				options.PrometheusRegistry = prometheus.NewRegistry()
-				closeFunc, err := prometheusmetrics.ActiveUsers(ctx, options.PrometheusRegistry, options.Database, 0)
+				closeUsersFunc, err := prometheusmetrics.ActiveUsers(ctx, options.PrometheusRegistry, options.Database, 0)
 				if err != nil {
 					return xerrors.Errorf("register active users prometheus metric: %w", err)
 				}
-				defer closeFunc()
+				defer closeUsersFunc()
+
+				closeWorkspacesFunc, err := prometheusmetrics.Workspaces(ctx, options.PrometheusRegistry, options.Database, 0)
+				if err != nil {
+					return xerrors.Errorf("register workspaces prometheus metric: %w", err)
+				}
+				defer closeWorkspacesFunc()
 
 				//nolint:revive
 				defer serveHandler(ctx, logger, promhttp.InstrumentMetricHandler(

cli/server_test.go

@@ -416,6 +416,7 @@ func TestServer(t *testing.T) {
 
 		scanner := bufio.NewScanner(res.Body)
 		hasActiveUsers := false
+		hasWorkspaces := false
 		for scanner.Scan() {
 			// This metric is manually registered to be tracked in the server. That's
 			// why we test it's tracked here.
@@ -423,9 +424,15 @@ func TestServer(t *testing.T) {
 				hasActiveUsers = true
 				continue
 			}
+			if strings.HasPrefix(scanner.Text(), "coderd_api_workspace_latest_build_total") {
+				hasWorkspaces = true
+				continue
+			}
+			t.Logf("scanned %s", scanner.Text())
 		}
 		require.NoError(t, scanner.Err())
 		require.True(t, hasActiveUsers)
+		require.True(t, hasWorkspaces)
 		cancelFunc()
 		<-serverErr
 	})