Upgrade golangci-lint and fixes some linting errors. (#22909)

Example: https://play.golang.org/p/cfPIPG3BwjJ

pkg/api/login.go

@@ -2,6 +2,7 @@ package api
 
 import (
 	"encoding/hex"
+	"errors"
 	"net/url"
 	"strings"
 
@@ -14,6 +15,7 @@ import (
 	"github.com/grafana/grafana/pkg/models"
 	"github.com/grafana/grafana/pkg/setting"
 	"github.com/grafana/grafana/pkg/util"
+	"github.com/grafana/grafana/pkg/util/errutil"
 )
 
 const (
@@ -85,7 +87,12 @@ func (hs *HTTPServer) LoginView(c *models.ReqContext) {
 	if c.IsSignedIn {
 		// Assign login token to auth proxy users if enable_login_token = true
 		if setting.AuthProxyEnabled && setting.AuthProxyEnableLoginToken {
-			hs.loginAuthProxyUser(c)
+			user := &models.User{Id: c.SignedInUser.UserId, Email: c.SignedInUser.Email, Login: c.SignedInUser.Login}
+			err := hs.loginUserWithUser(user, c)
+			if err != nil {
+				c.Handle(500, "Failed to sign in user", err)
+				return
+			}
 		}
 
 		if redirectTo, _ := url.QueryUnescape(c.GetCookie("redirect_to")); len(redirectTo) > 0 {
@@ -107,14 +114,6 @@ func (hs *HTTPServer) LoginView(c *models.ReqContext) {
 	c.HTML(200, getViewIndex(), viewData)
 }
 
-func (hs *HTTPServer) loginAuthProxyUser(c *models.ReqContext) {
-	hs.loginUserWithUser(&models.User{
-		Id:    c.SignedInUser.UserId,
-		Email: c.SignedInUser.Email,
-		Login: c.SignedInUser.Login,
-	}, c)
-}
-
 func tryOAuthAutoLogin(c *models.ReqContext) bool {
 	if !setting.OAuthAutoLogin {
 		return false
@@ -171,7 +170,10 @@ func (hs *HTTPServer) LoginPost(c *models.ReqContext, cmd dtos.LoginCommand) Res
 
 	user := authQuery.User
 
-	hs.loginUserWithUser(user, c)
+	err := hs.loginUserWithUser(user, c)
+	if err != nil {
+		return Error(500, "Error while signing in user", err)
+	}
 
 	result := map[string]interface{}{
 		"message": "Logged in",
@@ -190,17 +192,19 @@ func (hs *HTTPServer) LoginPost(c *models.ReqContext, cmd dtos.LoginCommand) Res
 	return JSON(200, result)
 }
 
-func (hs *HTTPServer) loginUserWithUser(user *models.User, c *models.ReqContext) {
+func (hs *HTTPServer) loginUserWithUser(user *models.User, c *models.ReqContext) error {
 	if user == nil {
-		hs.log.Error("user login with nil user")
+		return errors.New("could not login user")
 	}
 
 	userToken, err := hs.AuthTokenService.CreateToken(c.Req.Context(), user.Id, c.RemoteAddr(), c.Req.UserAgent())
 	if err != nil {
-		hs.log.Error("failed to create auth token", "error", err)
+		return errutil.Wrap("failed to create auth token", err)
 	}
+
 	hs.log.Info("Successful Login", "User", user.Email)
 	middleware.WriteSessionCookie(c, userToken.UnhashedToken, hs.Cfg.LoginMaxLifetimeDays)
+	return nil
 }
 
 func (hs *HTTPServer) Logout(c *models.ReqContext) {

pkg/api/login_oauth.go

@@ -218,7 +218,11 @@ func (hs *HTTPServer) OAuthLogin(ctx *models.ReqContext) {
 	}
 
 	// login
-	hs.loginUserWithUser(cmd.Result, ctx)
+	err = hs.loginUserWithUser(cmd.Result, ctx)
+	if err != nil {
+		hs.redirectWithError(ctx, err)
+		return
+	}
 
 	metrics.MApiLoginOAuth.Inc()
 

pkg/api/org_invite.go

@@ -197,7 +197,10 @@ func (hs *HTTPServer) CompleteInvite(c *models.ReqContext, completeInvite dtos.C
 		return rsp
 	}
 
-	hs.loginUserWithUser(user, c)
+	err := hs.loginUserWithUser(user, c)
+	if err != nil {
+		return Error(500, "failed to accept invite", err)
+	}
 
 	metrics.MApiUserSignUpCompleted.Inc()
 	metrics.MApiUserSignUpInvite.Inc()

pkg/api/signup.go

@@ -117,7 +117,11 @@ func (hs *HTTPServer) SignUpStep2(c *models.ReqContext, form dtos.SignUpStep2For
 		apiResponse["code"] = "redirect-to-select-org"
 	}
 
-	hs.loginUserWithUser(user, c)
+	err := hs.loginUserWithUser(user, c)
+	if err != nil {
+		return Error(500, "failed to login user", err)
+	}
+
 	metrics.MApiUserSignUpCompleted.Inc()
 
 	return JSON(200, apiResponse)