feat: add prometheus metrics to database.Store (#7713)

* Adds dbmetrics package and wraps database.Store with a Prometheus HistogramVec of timings.
* Adds Wrappers method to database.Store to avoid double-wrapping interfaces
* Fixes test flake in TestLicensesListFake

coderd/database/db.go

@@ -24,11 +24,20 @@ type Store interface {
 	querier
 	// customQuerier contains custom queries that are not generated.
 	customQuerier
+	// wrapper allows us to detect if the interface has been wrapped.
+	wrapper
 
 	Ping(ctx context.Context) (time.Duration, error)
 	InTx(func(Store) error, *sql.TxOptions) error
 }
 
+type wrapper interface {
+	// Wrappers returns a list of wrappers that have been applied to the store.
+	// This is used to detect if the store has already wrapped, and avoid
+	// double-wrapping.
+	Wrappers() []string
+}
+
 // DBTX represents a database connection or transaction.
 type DBTX interface {
 	ExecContext(context.Context, string, ...interface{}) (sql.Result, error)
@@ -60,6 +69,10 @@ type sqlQuerier struct {
 	db  DBTX
 }
 
+func (*sqlQuerier) Wrappers() []string {
+	return []string{}
+}
+
 // Ping returns the time it takes to ping the database.
 func (q *sqlQuerier) Ping(ctx context.Context) (time.Duration, error) {
 	start := time.Now()

coderd/database/dbauthz/dbauthz.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 
 	"github.com/google/uuid"
+	"golang.org/x/exp/slices"
 	"golang.org/x/xerrors"
 
 	"github.com/open-policy-agent/opa/topdown"
@@ -17,6 +18,8 @@ import (
 
 var _ database.Store = (*querier)(nil)
 
+const wrapname = "dbauthz.querier"
+
 // NoActorError wraps ErrNoRows for the api to return a 404. This is the correct
 // response when the user is not authorized.
 var NoActorError = xerrors.Errorf("no authorization actor in context: %w", sql.ErrNoRows)
@@ -89,7 +92,7 @@ type querier struct {
 func New(db database.Store, authorizer rbac.Authorizer, logger slog.Logger) database.Store {
 	// If the underlying db store is already a querier, return it.
 	// Do not double wrap.
-	if _, ok := db.(*querier); ok {
+	if slices.Contains(db.Wrappers(), wrapname) {
 		return db
 	}
 	return &querier{
@@ -99,6 +102,10 @@ func New(db database.Store, authorizer rbac.Authorizer, logger slog.Logger) data
 	}
 }
 
+func (q *querier) Wrappers() []string {
+	return append(q.db.Wrappers(), wrapname)
+}
+
 // authorizeContext is a helper function to authorize an action on an object.
 func (q *querier) authorizeContext(ctx context.Context, action rbac.Action, object rbac.Objecter) error {
 	act, ok := ActorFromContext(ctx)

coderd/database/dbauthz/dbauthz_test.go

@@ -138,7 +138,7 @@ func TestDBAuthzRecursive(t *testing.T) {
 		for i := 2; i < method.Type.NumIn(); i++ {
 			ins = append(ins, reflect.New(method.Type.In(i)).Elem())
 		}
-		if method.Name == "InTx" || method.Name == "Ping" {
+		if method.Name == "InTx" || method.Name == "Ping" || method.Name == "Wrappers" {
 			continue
 		}
 		// Log the name of the last method, so if there is a panic, it is

coderd/database/dbauthz/setup_test.go

@@ -8,6 +8,7 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/golang/mock/gomock"
 	"github.com/google/uuid"
 	"github.com/open-policy-agent/opa/topdown"
 	"github.com/stretchr/testify/require"
@@ -19,14 +20,16 @@ import (
 	"github.com/coder/coder/coderd/database"
 	"github.com/coder/coder/coderd/database/dbauthz"
 	"github.com/coder/coder/coderd/database/dbfake"
+	"github.com/coder/coder/coderd/database/dbmock"
 	"github.com/coder/coder/coderd/rbac"
 	"github.com/coder/coder/coderd/rbac/regosql"
 	"github.com/coder/coder/coderd/util/slice"
 )
 
 var skipMethods = map[string]string{
-	"InTx": "Not relevant",
-	"Ping": "Not relevant",
+	"InTx":     "Not relevant",
+	"Ping":     "Not relevant",
+	"Wrappers": "Not relevant",
 }
 
 // TestMethodTestSuite runs MethodTestSuite.
@@ -52,7 +55,11 @@ type MethodTestSuite struct {
 // SetupSuite sets up the suite by creating a map of all methods on querier
 // and setting their count to 0.
 func (s *MethodTestSuite) SetupSuite() {
-	az := dbauthz.New(nil, nil, slog.Make())
+	ctrl := gomock.NewController(s.T())
+	mockStore := dbmock.NewMockStore(ctrl)
+	// We intentionally set no expectations apart from this.
+	mockStore.EXPECT().Wrappers().Return([]string{}).AnyTimes()
+	az := dbauthz.New(mockStore, nil, slog.Make())
 	// Take the underlying type of the interface.
 	azt := reflect.TypeOf(az).Elem()
 	s.methodAccounting = make(map[string]int)

coderd/database/dbfake/databasefake.go

@@ -97,6 +97,10 @@ type fakeQuerier struct {
 	*data
 }
 
+func (*fakeQuerier) Wrappers() []string {
+	return []string{}
+}
+
 type fakeTx struct {
 	*fakeQuerier
 	locks map[int64]struct{}

coderd/database/dbmock/store.go

@@ -3233,3 +3233,17 @@ func (mr *MockStoreMockRecorder) UpsertServiceBanner(arg0, arg1 interface{}) *go
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "UpsertServiceBanner", reflect.TypeOf((*MockStore)(nil).UpsertServiceBanner), arg0, arg1)
 }
+
+// Wrappers mocks base method.
+func (m *MockStore) Wrappers() []string {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "Wrappers")
+	ret0, _ := ret[0].([]string)
+	return ret0
+}
+
+// Wrappers indicates an expected call of Wrappers.
+func (mr *MockStoreMockRecorder) Wrappers() *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Wrappers", reflect.TypeOf((*MockStore)(nil).Wrappers))
+}