Chore: Enable errorlint linter (#29227)

* Enable errorlint linter
* Handle wrapped errors

Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>
Co-authored-by: Emil Tullstedt <emil.tullstedt@grafana.com>

pkg/cmd/grafana-cli/services/api_client.go

@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"crypto/md5"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -25,9 +26,8 @@ type GrafanaComClient struct {
 func (client *GrafanaComClient) GetPlugin(pluginId, repoUrl string) (models.Plugin, error) {
 	logger.Debugf("getting plugin metadata from: %v pluginId: %v \n", repoUrl, pluginId)
 	body, err := sendRequestGetBytes(HttpClient, repoUrl, "repo", pluginId)
-
 	if err != nil {
-		if err == ErrNotFoundError {
+		if errors.Is(err, ErrNotFoundError) {
 			return models.Plugin{}, errutil.Wrap("Failed to find requested plugin, check if the plugin_id is correct", err)
 		}
 		return models.Plugin{}, errutil.Wrap("Failed to send request", err)

pkg/cmd/grafana-cli/services/api_client_test.go

@@ -2,6 +2,7 @@ package services
 
 import (
 	"bytes"
+	"errors"
 	"io"
 	"io/ioutil"
 	"net/http"
@@ -74,8 +75,9 @@ func makeBody(body string) io.ReadCloser {
 }
 
 func asBadRequestError(t *testing.T, err error) *BadRequestError {
-	if badRequestError, ok := err.(*BadRequestError); ok {
-		return badRequestError
+	var badErr *BadRequestError
+	if errors.As(err, &badErr) {
+		return badErr
 	}
 	assert.FailNow(t, "Error was not of type BadRequestError")
 	return nil

pkg/middleware/auth_proxy/auth_proxy.go

@@ -2,6 +2,7 @@ package authproxy
 
 import (
 	"encoding/hex"
+	"errors"
 	"fmt"
 	"hash/fnv"
 	"net"
@@ -180,12 +181,12 @@ func (auth *AuthProxy) Login(logger log.Logger, ignoreCache bool) (int64, *Error
 	}
 
 	if isLDAPEnabled() {
-		id, e := auth.LoginViaLDAP()
-		if e != nil {
-			if e == ldap.ErrInvalidCredentials {
+		id, err := auth.LoginViaLDAP()
+		if err != nil {
+			if errors.Is(err, ldap.ErrInvalidCredentials) {
 				return 0, newError("proxy authentication required", ldap.ErrInvalidCredentials)
 			}
-			return 0, newError("failed to get the user", e)
+			return 0, newError("failed to get the user", err)
 		}
 
 		return id, nil

pkg/middleware/middleware.go

@@ -2,6 +2,7 @@ package middleware
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"net/url"
 	"strconv"
@@ -182,7 +183,7 @@ func initContextWithBasicAuth(ctx *models.ReqContext, orgId int64) bool {
 			"err", err,
 		)
 
-		if err == models.ErrUserNotFound {
+		if errors.Is(err, models.ErrUserNotFound) {
 			err = login.ErrInvalidCredentials
 		}
 		ctx.JsonApiErr(401, errStringInvalidUsernamePassword, err)
@@ -250,7 +251,7 @@ func rotateEndOfRequestFunc(ctx *models.ReqContext, authTokenService models.User
 
 		// if the request is cancelled by the client we should not try
 		// to rotate the token since the client would not accept any result.
-		if ctx.Context.Req.Context().Err() == context.Canceled {
+		if errors.Is(ctx.Context.Req.Context().Err(), context.Canceled) {
 			return
 		}
 

pkg/middleware/recovery.go

@@ -17,6 +17,7 @@ package middleware
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"net/http"
@@ -102,7 +103,7 @@ func function(pc uintptr) []byte {
 func Recovery() macaron.Handler {
 	return func(c *macaron.Context) {
 		defer func() {
-			if err := recover(); err != nil {
+			if r := recover(); r != nil {
 				panicLogger := log.Root
 				// try to get request logger
 				if ctx, ok := c.Data["ctx"]; ok {
@@ -110,16 +111,18 @@ func Recovery() macaron.Handler {
 					panicLogger = ctxTyped.Logger
 				}
 
-				// http.ErrAbortHandler is suppressed by default in the http package
-				// and used as a signal for aborting requests. Suppresses stacktrace
-				// since it doesn't add any important information.
-				if err == http.ErrAbortHandler {
-					panicLogger.Error("Request error", "error", err)
-					return
+				if err, ok := r.(error); ok {
+					// http.ErrAbortHandler is suppressed by default in the http package
+					// and used as a signal for aborting requests. Suppresses stacktrace
+					// since it doesn't add any important information.
+					if errors.Is(err, http.ErrAbortHandler) {
+						panicLogger.Error("Request error", "error", err)
+						return
+					}
 				}
 
 				stack := stack(3)
-				panicLogger.Error("Request error", "error", err, "stack", string(stack))
+				panicLogger.Error("Request error", "error", r, "stack", string(stack))
 
 				// if response has already been written, skip.
 				if c.Written() {
@@ -131,8 +134,8 @@ func Recovery() macaron.Handler {
 				c.Data["Theme"] = setting.DefaultTheme
 
 				if setting.Env == setting.Dev {
-					if theErr, ok := err.(error); ok {
-						c.Data["Title"] = theErr.Error()
+					if err, ok := r.(error); ok {
+						c.Data["Title"] = err.Error()
 					}
 
 					c.Data["ErrorMsg"] = string(stack)

pkg/services/alerting/conditions/query.go

 package conditions
 
 import (
+	"errors"
 	"fmt"
 	"strings"
 	"time"
@@ -158,7 +159,7 @@ func (c *QueryCondition) executeQuery(context *alerting.EvalContext, timeRange *
 
 	resp, err := c.HandleRequest(context.Ctx, getDsInfo.Result, req)
 	if err != nil {
-		if err == gocontext.DeadlineExceeded {
+		if errors.Is(err, gocontext.DeadlineExceeded) {
 			return nil, fmt.Errorf("alert execution exceeded the timeout")
 		}
 

pkg/services/alerting/extractor.go

@@ -167,7 +167,7 @@ func (e *DashAlertExtractor) getAlertFromPanels(jsonWithPanels *simplejson.Json,
 			}
 
 			if err := bus.Dispatch(&dsFilterQuery); err != nil {
-				if err != bus.ErrHandlerNotFound {
+				if !errors.Is(err, bus.ErrHandlerNotFound) {
 					return nil, err
 				}
 			} else {

pkg/services/alerting/notifier.go

@@ -2,6 +2,7 @@ package alerting
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"time"
 
@@ -159,11 +160,11 @@ func (n *notificationService) sendNotification(evalContext *EvalContext, notifie
 		}
 
 		err := bus.DispatchCtx(evalContext.Ctx, setPendingCmd)
-		if err == models.ErrAlertNotificationStateVersionConflict {
-			return nil
-		}
-
 		if err != nil {
+			if errors.Is(err, models.ErrAlertNotificationStateVersionConflict) {
+				return nil
+			}
+
 			return err
 		}
 

pkg/services/alerting/notifiers/threema_test.go

 package notifiers
 
 import (
+	"errors"
 	"testing"
 
 	"github.com/grafana/grafana/pkg/components/simplejson"
@@ -70,7 +71,9 @@ func TestThreemaNotifier(t *testing.T) {
 
 				not, err := NewThreemaNotifier(model)
 				So(not, ShouldBeNil)
-				So(err.(alerting.ValidationError).Reason, ShouldEqual, "Invalid Threema Gateway ID: Must start with a *")
+				var valErr alerting.ValidationError
+				So(errors.As(err, &valErr), ShouldBeTrue)
+				So(valErr.Reason, ShouldEqual, "Invalid Threema Gateway ID: Must start with a *")
 			})
 
 			Convey("invalid Threema Gateway IDs should be rejected (length)", func() {
@@ -90,7 +93,9 @@ func TestThreemaNotifier(t *testing.T) {
 
 				not, err := NewThreemaNotifier(model)
 				So(not, ShouldBeNil)
-				So(err.(alerting.ValidationError).Reason, ShouldEqual, "Invalid Threema Gateway ID: Must be 8 characters long")
+				var valErr alerting.ValidationError
+				So(errors.As(err, &valErr), ShouldBeTrue)
+				So(valErr.Reason, ShouldEqual, "Invalid Threema Gateway ID: Must be 8 characters long")
 			})
 
 			Convey("invalid Threema Recipient IDs should be rejected (length)", func() {
@@ -110,7 +115,9 @@ func TestThreemaNotifier(t *testing.T) {
 
 				not, err := NewThreemaNotifier(model)
 				So(not, ShouldBeNil)
-				So(err.(alerting.ValidationError).Reason, ShouldEqual, "Invalid Threema Recipient ID: Must be 8 characters long")
+				var valErr alerting.ValidationError
+				So(errors.As(err, &valErr), ShouldBeTrue)
+				So(valErr.Reason, ShouldEqual, "Invalid Threema Recipient ID: Must be 8 characters long")
 			})
 		})
 	})

pkg/services/alerting/result_handler.go

@@ -59,12 +59,12 @@ func (handler *defaultResultHandler) handle(evalContext *EvalContext) error {
 		}
 
 		if err := bus.Dispatch(cmd); err != nil {
-			if err == models.ErrCannotChangeStateOnPausedAlert {
+			if errors.Is(err, models.ErrCannotChangeStateOnPausedAlert) {
 				handler.log.Error("Cannot change state on alert that's paused", "error", err)
 				return err
 			}
 
-			if err == models.ErrRequiresNewState {
+			if errors.Is(err, models.ErrRequiresNewState) {
 				handler.log.Info("Alert already updated")
 				return nil
 			}

pkg/services/alerting/rule_test.go

@@ -7,6 +7,8 @@ import (
 	"github.com/grafana/grafana/pkg/models"
 	"github.com/grafana/grafana/pkg/services/sqlstore"
 	. "github.com/smartystreets/goconvey/convey"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 type FakeCondition struct{}
@@ -34,15 +36,15 @@ func TestAlertRuleFrequencyParsing(t *testing.T) {
 	}
 
 	for _, tc := range tcs {
-		r, err := getTimeDurationStringToSeconds(tc.input)
-		if err != tc.err {
-			t.Errorf("expected error: '%v' got: '%v'", tc.err, err)
-			return
-		}
-
-		if r != tc.result {
-			t.Errorf("expected result: %d got %d", tc.result, r)
-		}
+		t.Run(tc.input, func(t *testing.T) {
+			r, err := getTimeDurationStringToSeconds(tc.input)
+			if tc.err == nil {
+				require.NoError(t, err)
+			} else {
+				require.EqualError(t, err, tc.err.Error())
+			}
+			assert.Equal(t, tc.result, r)
+		})
 	}
 }
 

pkg/services/dashboards/folder_service.go

 package dashboards
 
 import (
+	"errors"
+
 	"github.com/grafana/grafana/pkg/bus"
 	"github.com/grafana/grafana/pkg/models"
 	"github.com/grafana/grafana/pkg/services/guardian"
@@ -209,31 +211,31 @@ func dashToFolder(dash *models.Dashboard) *models.Folder {
 }
 
 func toFolderError(err error) error {
-	if err == models.ErrDashboardTitleEmpty {
+	if errors.Is(err, models.ErrDashboardTitleEmpty) {
 		return models.ErrFolderTitleEmpty
 	}
 
-	if err == models.ErrDashboardUpdateAccessDenied {
+	if errors.Is(err, models.ErrDashboardUpdateAccessDenied) {
 		return models.ErrFolderAccessDenied
 	}
 
-	if err == models.ErrDashboardWithSameNameInFolderExists {
+	if errors.Is(err, models.ErrDashboardWithSameNameInFolderExists) {
 		return models.ErrFolderSameNameExists
 	}
 
-	if err == models.ErrDashboardWithSameUIDExists {
+	if errors.Is(err, models.ErrDashboardWithSameUIDExists) {
 		return models.ErrFolderWithSameUIDExists
 	}
 
-	if err == models.ErrDashboardVersionMismatch {
+	if errors.Is(err, models.ErrDashboardVersionMismatch) {
 		return models.ErrFolderVersionMismatch
 	}
 
-	if err == models.ErrDashboardNotFound {
+	if errors.Is(err, models.ErrDashboardNotFound) {
 		return models.ErrFolderNotFound
 	}
 
-	if err == models.ErrDashboardFailedGenerateUniqueUid {
+	if errors.Is(err, models.ErrDashboardFailedGenerateUniqueUid) {
 		err = models.ErrFolderFailedGenerateUniqueUid
 	}
 

pkg/services/dashboards/folder_service_test.go

@@ -5,6 +5,7 @@ import (
 
 	"github.com/grafana/grafana/pkg/bus"
 	"github.com/grafana/grafana/pkg/models"
+	"github.com/stretchr/testify/assert"
 
 	"github.com/grafana/grafana/pkg/services/guardian"
 
@@ -194,9 +195,8 @@ func TestFolderService(t *testing.T) {
 
 			for _, tc := range testCases {
 				actualError := toFolderError(tc.ActualError)
-				if actualError != tc.ExpectedError {
-					t.Errorf("For error '%s' expected error '%s', actual '%s'", tc.ActualError, tc.ExpectedError, actualError)
-				}
+				assert.EqualErrorf(t, actualError, tc.ExpectedError.Error(),
+					"For error '%s' expected error '%s', actual '%s'", tc.ActualError, tc.ExpectedError, actualError)
 			}
 		})
 	})

pkg/services/guardian/guardian_test.go

 package guardian
 
 import (
+	"errors"
 	"fmt"
 	"runtime"
 	"testing"
@@ -300,7 +301,7 @@ func (sc *scenarioContext) verifyDuplicatePermissionsShouldNotBeAllowed() {
 		sc.updatePermissions = p
 		_, err := sc.g.CheckPermissionBeforeUpdate(models.PERMISSION_ADMIN, p)
 
-		if err != ErrGuardianPermissionExists {
+		if !errors.Is(err, ErrGuardianPermissionExists) {
 			sc.reportFailure(tc, ErrGuardianPermissionExists, err)
 		}
 		sc.reportSuccess()
@@ -314,8 +315,7 @@ func (sc *scenarioContext) verifyDuplicatePermissionsShouldNotBeAllowed() {
 		}
 		sc.updatePermissions = p
 		_, err := sc.g.CheckPermissionBeforeUpdate(models.PERMISSION_ADMIN, p)
-
-		if err != ErrGuardianPermissionExists {
+		if !errors.Is(err, ErrGuardianPermissionExists) {
 			sc.reportFailure(tc, ErrGuardianPermissionExists, err)
 		}
 		sc.reportSuccess()
@@ -330,7 +330,7 @@ func (sc *scenarioContext) verifyDuplicatePermissionsShouldNotBeAllowed() {
 		sc.updatePermissions = p
 		_, err := sc.g.CheckPermissionBeforeUpdate(models.PERMISSION_ADMIN, p)
 
-		if err != ErrGuardianPermissionExists {
+		if !errors.Is(err, ErrGuardianPermissionExists) {
 			sc.reportFailure(tc, ErrGuardianPermissionExists, err)
 		}
 		sc.reportSuccess()
@@ -344,8 +344,7 @@ func (sc *scenarioContext) verifyDuplicatePermissionsShouldNotBeAllowed() {
 		}
 		sc.updatePermissions = p
 		_, err := sc.g.CheckPermissionBeforeUpdate(models.PERMISSION_ADMIN, p)
-
-		if err != ErrGuardianPermissionExists {
+		if !errors.Is(err, ErrGuardianPermissionExists) {
 			sc.reportFailure(tc, ErrGuardianPermissionExists, err)
 		}
 		sc.reportSuccess()
@@ -358,8 +357,7 @@ func (sc *scenarioContext) verifyDuplicatePermissionsShouldNotBeAllowed() {
 		}
 		sc.updatePermissions = p
 		_, err := sc.g.CheckPermissionBeforeUpdate(models.PERMISSION_ADMIN, p)
-
-		if err != ErrGuardianPermissionExists {
+		if !errors.Is(err, ErrGuardianPermissionExists) {
 			sc.reportFailure(tc, ErrGuardianPermissionExists, err)
 		}
 		sc.reportSuccess()
@@ -402,7 +400,6 @@ func (sc *scenarioContext) verifyUpdateDashboardPermissionsShouldBeAllowed(pt pe
 
 			sc.updatePermissions = permissionList
 			ok, err := sc.g.CheckPermissionBeforeUpdate(models.PERMISSION_ADMIN, permissionList)
-
 			if err != nil {
 				sc.reportFailure(tc, nil, err)
 			}
@@ -442,7 +439,6 @@ func (sc *scenarioContext) verifyUpdateDashboardPermissionsShouldNotBeAllowed(pt
 
 			sc.updatePermissions = permissionList
 			ok, err := sc.g.CheckPermissionBeforeUpdate(models.PERMISSION_ADMIN, permissionList)
-
 			if err != nil {
 				sc.reportFailure(tc, nil, err)
 			}
@@ -505,7 +501,6 @@ func (sc *scenarioContext) verifyUpdateChildDashboardPermissionsShouldBeAllowed(
 
 			sc.updatePermissions = permissionList
 			ok, err := sc.g.CheckPermissionBeforeUpdate(models.PERMISSION_ADMIN, permissionList)
-
 			if err != nil {
 				sc.reportFailure(tc, nil, err)
 			}
@@ -568,7 +563,6 @@ func (sc *scenarioContext) verifyUpdateChildDashboardPermissionsShouldNotBeAllow
 
 			sc.updatePermissions = permissionList
 			ok, err := sc.g.CheckPermissionBeforeUpdate(models.PERMISSION_ADMIN, permissionList)
-
 			if err != nil {
 				sc.reportFailure(tc, nil, err)
 			}
@@ -616,8 +610,7 @@ func (sc *scenarioContext) verifyUpdateChildDashboardPermissionsWithOverrideShou
 
 			sc.updatePermissions = permissionList
 			_, err := sc.g.CheckPermissionBeforeUpdate(models.PERMISSION_ADMIN, permissionList)
-
-			if err != ErrGuardianOverride {
+			if !errors.Is(err, ErrGuardianOverride) {
 				sc.reportFailure(tc, ErrGuardianOverride, err)
 			}
 			sc.reportSuccess()
@@ -665,7 +658,6 @@ func (sc *scenarioContext) verifyUpdateChildDashboardPermissionsWithOverrideShou
 			}
 			sc.updatePermissions = permissionList
 			ok, err := sc.g.CheckPermissionBeforeUpdate(models.PERMISSION_ADMIN, permissionList)
-
 			if err != nil {
 				sc.reportFailure(tc, nil, err)
 			}

pkg/services/ldap/ldap.go

@@ -475,11 +475,11 @@ func (server *Server) AdminBind() error {
 func (server *Server) userBind(path, password string) error {
 	err := server.Connection.Bind(path, password)
 	if err != nil {
-		if ldapErr, ok := err.(*ldap.Error); ok {
-			if ldapErr.ResultCode == 49 {
-				return ErrInvalidCredentials
-			}
+		var ldapErr *ldap.Error
+		if errors.As(err, &ldapErr) && ldapErr.ResultCode == 49 {
+			return ErrInvalidCredentials
 		}
+
 		return err
 	}
 

pkg/services/multildap/multildap.go

@@ -234,7 +234,7 @@ func isSilentError(err error) bool {
 	continueErrs := []error{ErrInvalidCredentials, ErrCouldNotFindUser}
 
 	for _, cerr := range continueErrs {
-		if err == cerr {
+		if errors.Is(err, cerr) {
 			return true
 		}
 	}

pkg/services/oauthtoken/oauth_token_util.go

@@ -2,6 +2,7 @@ package oauthtoken
 
 import (
 	"context"
+	"errors"
 
 	"github.com/grafana/grafana/pkg/bus"
 	"github.com/grafana/grafana/pkg/infra/log"
@@ -23,7 +24,7 @@ func GetCurrentOAuthToken(ctx context.Context, user *models.SignedInUser) *oauth
 
 	authInfoQuery := &models.GetAuthInfoQuery{UserId: user.UserId}
 	if err := bus.Dispatch(authInfoQuery); err != nil {
-		if err == models.ErrUserNotFound {
+		if errors.Is(err, models.ErrUserNotFound) {
 			// Not necessarily an error.  User may be logged in another way.
 			logger.Debug("no OAuth token for user found", "userId", user.UserId, "username", user.Login)
 		} else {

pkg/services/provisioning/dashboards/file_reader.go

@@ -117,8 +117,7 @@ func (fr *FileReader) startWalkingDisk() error {
 // storeDashboardsInFolder saves dashboards from the filesystem on disk to the folder from config
 func (fr *FileReader) storeDashboardsInFolder(filesFoundOnDisk map[string]os.FileInfo, dashboardRefs map[string]*models.DashboardProvisioning, sanityChecker *provisioningSanityChecker) error {
 	folderID, err := getOrCreateFolderID(fr.Cfg, fr.dashboardProvisioningService, fr.Cfg.Folder)
-
-	if err != nil && err != ErrFolderNameMissing {
+	if err != nil && !errors.Is(err, ErrFolderNameMissing) {
 		return err
 	}
 
@@ -145,7 +144,7 @@ func (fr *FileReader) storeDashboardsInFoldersFromFileStructure(filesFoundOnDisk
 		}
 
 		folderID, err := getOrCreateFolderID(fr.Cfg, fr.dashboardProvisioningService, folderName)
-		if err != nil && err != ErrFolderNameMissing {
+		if err != nil && !errors.Is(err, ErrFolderNameMissing) {
 			return fmt.Errorf("can't provision folder %q from file system structure: %w", folderName, err)
 		}
 
@@ -264,12 +263,12 @@ func getOrCreateFolderID(cfg *config, service dashboards.DashboardProvisioningSe
 	cmd := &models.GetDashboardQuery{Slug: models.SlugifyTitle(folderName), OrgId: cfg.OrgID}
 	err := bus.Dispatch(cmd)
 
-	if err != nil && err != models.ErrDashboardNotFound {
+	if err != nil && !errors.Is(err, models.ErrDashboardNotFound) {
 		return 0, err
 	}
 
 	// dashboard folder not found. create one.
-	if err == models.ErrDashboardNotFound {
+	if errors.Is(err, models.ErrDashboardNotFound) {
 		dash := &dashboards.SaveDashboardDTO{}
 		dash.Dashboard = models.NewDashboardFolder(folderName)
 		dash.Dashboard.IsFolder = true

pkg/services/provisioning/datasources/datasources.go

@@ -45,11 +45,11 @@ func (dc *DatasourceProvisioner) apply(cfg *configs) error {
 	for _, ds := range cfg.Datasources {
 		cmd := &models.GetDataSourceByNameQuery{OrgId: ds.OrgID, Name: ds.Name}
 		err := bus.Dispatch(cmd)
-		if err != nil && err != models.ErrDataSourceNotFound {
+		if err != nil && !errors.Is(err, models.ErrDataSourceNotFound) {
 			return err
 		}
 
-		if err == models.ErrDataSourceNotFound {
+		if errors.Is(err, models.ErrDataSourceNotFound) {
 			dc.log.Info("inserting datasource from configuration ", "name", ds.Name, "uid", ds.UID)
 			insertCmd := createInsertCommand(ds)
 			if err := bus.Dispatch(insertCmd); err != nil {

pkg/services/provisioning/plugins/plugin_provisioner.go

 package plugins
 
 import (
+	"errors"
+
 	"github.com/grafana/grafana/pkg/bus"
 	"github.com/grafana/grafana/pkg/infra/log"
 	"github.com/grafana/grafana/pkg/models"
@@ -42,7 +44,7 @@ func (ap *PluginProvisioner) apply(cfg *pluginsAsConfig) error {
 		query := &models.GetPluginSettingByIdQuery{OrgId: app.OrgID, PluginId: app.PluginID}
 		err := bus.Dispatch(query)
 		if err != nil {
-			if err != models.ErrPluginSettingNotFound {
+			if !errors.Is(err, models.ErrPluginSettingNotFound) {
 				return err
 			}
 		} else {

pkg/services/rendering/http_mode.go

@@ -2,6 +2,7 @@ package rendering
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"net"
@@ -79,7 +80,7 @@ func (rs *RenderingService) renderViaHttp(ctx context.Context, renderKey string,
 	defer resp.Body.Close()
 
 	// check for timeout first
-	if reqContext.Err() == context.DeadlineExceeded {
+	if errors.Is(reqContext.Err(), context.DeadlineExceeded) {
 		rs.log.Info("Rendering timed out")
 		return nil, ErrTimeout
 	}
@@ -99,7 +100,7 @@ func (rs *RenderingService) renderViaHttp(ctx context.Context, renderKey string,
 	_, err = io.Copy(out, resp.Body)
 	if err != nil {
 		// check that we didn't timeout while receiving the response.
-		if reqContext.Err() == context.DeadlineExceeded {
+		if errors.Is(reqContext.Err(), context.DeadlineExceeded) {
 			rs.log.Info("Rendering timed out")
 			return nil, ErrTimeout
 		}

pkg/services/rendering/plugin_mode.go

@@ -2,6 +2,7 @@ package rendering
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"time"
 
@@ -45,7 +46,7 @@ func (rs *RenderingService) renderViaPluginV1(ctx context.Context, renderKey str
 	rs.log.Debug("calling renderer plugin", "req", req)
 
 	rsp, err := rs.pluginInfo.GrpcPluginV1.Render(ctx, req)
-	if ctx.Err() == context.DeadlineExceeded {
+	if errors.Is(ctx.Err(), context.DeadlineExceeded) {
 		rs.log.Info("Rendering timed out")
 		return nil, ErrTimeout
 	}
@@ -88,7 +89,7 @@ func (rs *RenderingService) renderViaPluginV2(ctx context.Context, renderKey str
 	rs.log.Debug("Calling renderer plugin", "req", req)
 
 	rsp, err := rs.pluginInfo.GrpcPluginV2.Render(ctx, req)
-	if ctx.Err() == context.DeadlineExceeded {
+	if errors.Is(ctx.Err(), context.DeadlineExceeded) {
 		rs.log.Info("Rendering timed out")
 		return nil, ErrTimeout
 	}

pkg/services/rendering/rendering.go

@@ -2,6 +2,7 @@ package rendering
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"math"
 	"net/url"
@@ -136,7 +137,7 @@ func (rs *RenderingService) Render(ctx context.Context, opts Opts) (*RenderResul
 	elapsedTime := time.Since(startTime).Milliseconds()
 	result, err := rs.render(ctx, opts)
 	if err != nil {
-		if err == ErrTimeout {
+		if errors.Is(err, ErrTimeout) {
 			metrics.MRenderingRequestTotal.WithLabelValues("timeout").Inc()
 			metrics.MRenderingSummary.WithLabelValues("timeout").Observe(float64(elapsedTime))
 		} else {

pkg/services/sqlstore/database_wrapper.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"database/sql"
 	"database/sql/driver"
+	"errors"
 	"time"
 
 	"github.com/gchaincl/sqlhooks"
@@ -87,7 +88,7 @@ func (h *databaseQueryWrapper) After(ctx context.Context, query string, args ...
 func (h *databaseQueryWrapper) OnError(ctx context.Context, err error, query string, args ...interface{}) error {
 	status := "error"
 	// https://golang.org/pkg/database/sql/driver/#ErrSkip
-	if err == nil || err == driver.ErrSkip {
+	if err == nil || errors.Is(err, driver.ErrSkip) {
 		status = "success"
 	}
 

pkg/services/sqlstore/migrator/migrator.go

 package migrator
 
 import (
+	"errors"
 	"time"
 
 	_ "github.com/go-sql-driver/mysql"
@@ -168,8 +169,8 @@ func (mg *Migrator) inTransaction(callback dbTransactionFunc) error {
 	}
 
 	if err := callback(sess); err != nil {
-		if rollErr := sess.Rollback(); err != rollErr {
-			return errutil.Wrapf(err, "Failed to roll back transaction due to error: %s", rollErr)
+		if rollErr := sess.Rollback(); !errors.Is(err, rollErr) {
+			return errutil.Wrapf(err, "failed to roll back transaction due to error: %s", rollErr)
 		}
 
 		return err

pkg/services/sqlstore/migrator/mysql_dialect.go

 package migrator
 
 import (
+	"errors"
 	"fmt"
 	"strconv"
 	"strings"
@@ -169,7 +170,8 @@ func (db *MySQLDialect) TruncateDBTables() error {
 }
 
 func (db *MySQLDialect) isThisError(err error, errcode uint16) bool {
-	if driverErr, ok := err.(*mysql.MySQLError); ok {
+	var driverErr *mysql.MySQLError
+	if errors.As(err, &driverErr) {
 		if driverErr.Number == errcode {
 			return true
 		}
@@ -183,7 +185,8 @@ func (db *MySQLDialect) IsUniqueConstraintViolation(err error) bool {
 }
 
 func (db *MySQLDialect) ErrorMessage(err error) string {
-	if driverErr, ok := err.(*mysql.MySQLError); ok {
+	var driverErr *mysql.MySQLError
+	if errors.As(err, &driverErr) {
 		return driverErr.Message
 	}
 	return ""

pkg/services/sqlstore/migrator/postgres_dialect.go

 package migrator
 
 import (
+	"errors"
 	"fmt"
 	"strconv"
 	"strings"
@@ -172,7 +173,8 @@ func (db *PostgresDialect) TruncateDBTables() error {
 }
 
 func (db *PostgresDialect) isThisError(err error, errcode string) bool {
-	if driverErr, ok := err.(*pq.Error); ok {
+	var driverErr *pq.Error
+	if errors.As(err, &driverErr) {
 		if string(driverErr.Code) == errcode {
 			return true
 		}
@@ -182,7 +184,8 @@ func (db *PostgresDialect) isThisError(err error, errcode string) bool {
 }
 
 func (db *PostgresDialect) ErrorMessage(err error) string {
-	if driverErr, ok := err.(*pq.Error); ok {
+	var driverErr *pq.Error
+	if errors.As(err, &driverErr) {
 		return driverErr.Message
 	}
 	return ""

pkg/services/sqlstore/migrator/sqlite_dialect.go

 package migrator
 
 import (
+	"errors"
 	"fmt"
 
 	"github.com/grafana/grafana/pkg/util/errutil"
@@ -120,7 +121,8 @@ func (db *SQLite3) TruncateDBTables() error {
 }
 
 func (db *SQLite3) isThisError(err error, errcode int) bool {
-	if driverErr, ok := err.(sqlite3.Error); ok {
+	var driverErr sqlite3.Error
+	if errors.As(err, &driverErr) {
 		if int(driverErr.ExtendedCode) == errcode {
 			return true
 		}
@@ -130,7 +132,8 @@ func (db *SQLite3) isThisError(err error, errcode int) bool {
 }
 
 func (db *SQLite3) ErrorMessage(err error) string {
-	if driverErr, ok := err.(sqlite3.Error); ok {
+	var driverErr sqlite3.Error
+	if errors.As(err, &driverErr) {
 		return driverErr.Error()
 	}
 	return ""

pkg/services/sqlstore/transactions.go

@@ -2,6 +2,7 @@ package sqlstore
 
 import (
 	"context"
+	"errors"
 	"time"
 
 	"github.com/grafana/grafana/pkg/bus"
@@ -42,8 +43,8 @@ func inTransactionWithRetryCtx(ctx context.Context, engine *xorm.Engine, callbac
 	err = callback(sess)
 
 	// special handling of database locked errors for sqlite, then we can retry 5 times
-	if sqlError, ok := err.(sqlite3.Error); ok && retry < 5 && sqlError.Code ==
-		sqlite3.ErrLocked || sqlError.Code == sqlite3.ErrBusy {
+	var sqlError sqlite3.Error
+	if errors.As(err, &sqlError) && retry < 5 && sqlError.Code == sqlite3.ErrLocked || sqlError.Code == sqlite3.ErrBusy {
 		if rollErr := sess.Rollback(); rollErr != nil {
 			return errutil.Wrapf(err, "Rolling back transaction due to error failed: %s", rollErr)
 		}

pkg/services/sqlstore/user_auth.go

@@ -2,6 +2,7 @@ package sqlstore
 
 import (
 	"encoding/base64"
+	"errors"
 	"time"
 
 	"github.com/grafana/grafana/pkg/bus"
@@ -33,7 +34,7 @@ func GetUserByAuthInfo(query *models.GetUserByAuthInfoQuery) error {
 		authQuery.AuthId = query.AuthId
 
 		err = GetAuthInfo(authQuery)
-		if err != models.ErrUserNotFound {
+		if !errors.Is(err, models.ErrUserNotFound) {
 			if err != nil {
 				return err
 			}

pkg/tsdb/cloudwatch/log_actions.go

@@ -2,6 +2,7 @@ package cloudwatch
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"sort"
 
@@ -258,11 +259,11 @@ func (e *cloudWatchExecutor) executeStopQuery(ctx context.Context, logsClient cl
 
 	response, err := logsClient.StopQueryWithContext(ctx, queryInput)
 	if err != nil {
-		awsErr, ok := err.(awserr.Error)
 		// If the query has already stopped by the time CloudWatch receives the stop query request,
 		// an "InvalidParameterException" error is returned. For our purposes though the query has been
 		// stopped, so we ignore the error.
-		if ok && awsErr.Code() == "InvalidParameterException" {
+		var awsErr awserr.Error
+		if errors.As(err, &awsErr) && awsErr.Code() == "InvalidParameterException" {
 			response = &cloudwatchlogs.StopQueryOutput{Success: aws.Bool(false)}
 			err = nil
 		}

pkg/tsdb/mysql/mysql.go

@@ -140,8 +140,10 @@ func (t *mysqlQueryResultTransformer) TransformQueryResult(columnTypes []*sql.Co
 }
 
 func (t *mysqlQueryResultTransformer) TransformQueryError(err error) error {
-	if driverErr, ok := err.(*mysql.MySQLError); ok {
-		if driverErr.Number != mysqlerr.ER_PARSE_ERROR && driverErr.Number != mysqlerr.ER_BAD_FIELD_ERROR && driverErr.Number != mysqlerr.ER_NO_SUCH_TABLE {
+	var driverErr *mysql.MySQLError
+	if errors.As(err, &driverErr) {
+		if driverErr.Number != mysqlerr.ER_PARSE_ERROR && driverErr.Number != mysqlerr.ER_BAD_FIELD_ERROR &&
+			driverErr.Number != mysqlerr.ER_NO_SUCH_TABLE {
 			t.log.Error("query error", "err", err)
 			return errQueryFailed
 		}

pkg/util/filepath.go

@@ -50,7 +50,7 @@ func walk(path string, info os.FileInfo, resolvedPath string, symlinkPathsFollow
 	}
 	err := walkFn(resolvedPath, info, nil)
 	if err != nil {
-		if info.IsDir() && err == ErrWalkSkipDir {
+		if info.IsDir() && errors.Is(err, ErrWalkSkipDir) {
 			err = nil
 		}
 		return err

scripts/go/configs/.golangci.toml

@@ -39,6 +39,10 @@ enable = [
   "varcheck",
   "whitespace",
   "gocyclo",
+  "typecheck",
+  "asciicheck",
+  "errorlint",
+  "sqlclosecheck",
 ]
 
 # Disabled linters (might want them later)
@@ -95,3 +99,7 @@ text = "404"
 [[issues.exclude-rules]]
 linters = ["misspell"]
 text = "Unknwon` is a misspelling of `Unknown"
+
+[[issues.exclude-rules]]
+linters = ["errorlint"]
+text = "non-wrapping format verb for fmt.Errorf"