Chore: Fix issues found by staticcheck (#28802)

* Fix linting issues

Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>

pkg/api/avatar/avatar.go

@@ -50,20 +50,20 @@ func New(hash string) *Avatar {
 	}
 }
 
-func (this *Avatar) Expired() bool {
+func (a *Avatar) Expired() bool {
-	return time.Since(this.timestamp) > (time.Minute * 10)
+	return time.Since(a.timestamp) > (time.Minute * 10)
 }
 
-func (this *Avatar) Encode(wr io.Writer) error {
+func (a *Avatar) Encode(wr io.Writer) error {
-	_, err := wr.Write(this.data.Bytes())
+	_, err := wr.Write(a.data.Bytes())
 	return err
 }
 
-func (this *Avatar) Update() (err error) {
+func (a *Avatar) Update() (err error) {
 	select {
 	case <-time.After(time.Second * 3):
-		err = fmt.Errorf("get gravatar image %s timeout", this.hash)
+		err = fmt.Errorf("get gravatar image %s timeout", a.hash)
-	case err = <-thunder.GoFetch(gravatarSource+this.hash+"?"+this.reqParams, this):
+	case err = <-thunder.GoFetch(gravatarSource+a.hash+"?"+a.reqParams, a):
 	}
 	return err
 }
@@ -75,7 +75,7 @@ type CacheServer struct {
 
 var validMD5 = regexp.MustCompile("^[a-fA-F0-9]{32}$")
 
-func (this *CacheServer) Handler(ctx *models.ReqContext) {
+func (a *CacheServer) Handler(ctx *models.ReqContext) {
 	hash := ctx.Params("hash")
 
 	if len(hash) != 32 || !validMD5.MatchString(hash) {
@@ -84,7 +84,7 @@ func (this *CacheServer) Handler(ctx *models.ReqContext) {
 	}
 
 	var avatar *Avatar
-	obj, exists := this.cache.Get(hash)
+	obj, exists := a.cache.Get(hash)
 	if exists {
 		avatar = obj.(*Avatar)
 	} else {
@@ -95,14 +95,14 @@ func (this *CacheServer) Handler(ctx *models.ReqContext) {
 		// The cache item is either expired or newly created, update it from the server
 		if err := avatar.Update(); err != nil {
 			log.Tracef("avatar update error: %v", err)
-			avatar = this.notFound
+			avatar = a.notFound
 		}
 	}
 
 	if avatar.notFound {
-		avatar = this.notFound
+		avatar = a.notFound
 	} else if !exists {
-		if err := this.cache.Add(hash, avatar, gocache.DefaultExpiration); err != nil {
+		if err := a.cache.Add(hash, avatar, gocache.DefaultExpiration); err != nil {
 			log.Tracef("Error adding avatar to cache: %s", err)
 		}
 	}
@@ -195,9 +195,9 @@ type thunderTask struct {
 	err error
 }
 
-func (this *thunderTask) Fetch() {
+func (a *thunderTask) Fetch() {
-	this.err = this.fetch()
+	a.err = a.fetch()
-	this.Done()
+	a.Done()
 }
 
 var client = &http.Client{
@@ -205,11 +205,11 @@ var client = &http.Client{
 	Transport: &http.Transport{Proxy: http.ProxyFromEnvironment},
 }
 
-func (this *thunderTask) fetch() error {
+func (a *thunderTask) fetch() error {
-	this.Avatar.timestamp = time.Now()
+	a.Avatar.timestamp = time.Now()
 
-	log.Debugf("avatar.fetch(fetch new avatar): %s", this.Url)
+	log.Debugf("avatar.fetch(fetch new avatar): %s", a.Url)
-	req, _ := http.NewRequest("GET", this.Url, nil)
+	req, _ := http.NewRequest("GET", a.Url, nil)
 	req.Header.Set("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,image/jpeg,image/png,*/*;q=0.8")
 	req.Header.Set("Accept-Encoding", "deflate,sdch")
 	req.Header.Set("Accept-Language", "zh-CN,zh;q=0.8")
@@ -217,19 +217,19 @@ func (this *thunderTask) fetch() error {
 	req.Header.Set("User-Agent", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/33.0.1750.154 Safari/537.36")
 	resp, err := client.Do(req)
 	if err != nil {
-		this.Avatar.notFound = true
+		a.Avatar.notFound = true
 		return fmt.Errorf("gravatar unreachable, %v", err)
 	}
 
 	defer resp.Body.Close()
 
 	if resp.StatusCode != 200 {
-		this.Avatar.notFound = true
+		a.Avatar.notFound = true
 		return fmt.Errorf("status code: %d", resp.StatusCode)
 	}
 
-	this.Avatar.data = &bytes.Buffer{}
+	a.Avatar.data = &bytes.Buffer{}
-	writer := bufio.NewWriter(this.Avatar.data)
+	writer := bufio.NewWriter(a.Avatar.data)
 
 	_, err = io.Copy(writer, resp.Body)
 	return err

pkg/tsdb/azuremonitor/applicationinsights-datasource.go

@@ -179,7 +179,7 @@ func (e *ApplicationInsightsDatasource) executeQuery(ctx context.Context, query
 
 	if res.StatusCode/100 != 2 {
 		azlog.Debug("Request failed", "status", res.Status, "body", string(body))
-		return nil, fmt.Errorf("Request failed status: %v", res.Status)
+		return nil, fmt.Errorf("request failed, status: %s", res.Status)
 	}
 
 	mr := MetricsResult{}
@@ -204,7 +204,7 @@ func (e *ApplicationInsightsDatasource) createRequest(ctx context.Context, dsInf
 	// find plugin
 	plugin, ok := plugins.DataSources[dsInfo.Type]
 	if !ok {
-		return nil, errors.New("Unable to find datasource plugin Azure Application Insights")
+		return nil, errors.New("unable to find datasource plugin Azure Application Insights")
 	}
 
 	cloudName := dsInfo.JsonData.Get("cloudName").MustString("azuremonitor")

pkg/tsdb/azuremonitor/azure-log-analytics-datasource.go

@@ -207,7 +207,7 @@ func (e *AzureLogAnalyticsDatasource) createRequest(ctx context.Context, dsInfo
 	req, err := http.NewRequest(http.MethodGet, u.String(), nil)
 	if err != nil {
 		azlog.Debug("Failed to create request", "error", err)
-		return nil, errutil.Wrap("Failed to create request", err)
+		return nil, errutil.Wrap("failed to create request", err)
 	}
 
 	req.Header.Set("Content-Type", "application/json")
@@ -216,7 +216,7 @@ func (e *AzureLogAnalyticsDatasource) createRequest(ctx context.Context, dsInfo
 	// find plugin
 	plugin, ok := plugins.DataSources[dsInfo.Type]
 	if !ok {
-		return nil, errors.New("Unable to find datasource plugin Azure Monitor")
+		return nil, errors.New("unable to find datasource plugin Azure Monitor")
 	}
 	cloudName := dsInfo.JsonData.Get("cloudName").MustString("azuremonitor")
 
@@ -272,7 +272,7 @@ func (e *AzureLogAnalyticsDatasource) unmarshalResponse(res *http.Response) (Azu
 
 	if res.StatusCode/100 != 2 {
 		azlog.Debug("Request failed", "status", res.Status, "body", string(body))
-		return AzureLogAnalyticsResponse{}, fmt.Errorf("Request failed status: %v: %w", res.Status, fmt.Errorf(string(body)))
+		return AzureLogAnalyticsResponse{}, fmt.Errorf("request failed, status: %s, body: %s", res.Status, string(body))
 	}
 
 	var data AzureLogAnalyticsResponse

pkg/tsdb/azuremonitor/azuremonitor-datasource.go

@@ -220,7 +220,7 @@ func (e *AzureMonitorDatasource) createRequest(ctx context.Context, dsInfo *mode
 	// find plugin
 	plugin, ok := plugins.DataSources[dsInfo.Type]
 	if !ok {
-		return nil, errors.New("Unable to find datasource plugin Azure Monitor")
+		return nil, errors.New("unable to find datasource plugin Azure Monitor")
 	}
 
 	cloudName := dsInfo.JsonData.Get("cloudName").MustString("azuremonitor")
@@ -263,7 +263,7 @@ func (e *AzureMonitorDatasource) unmarshalResponse(res *http.Response) (AzureMon
 
 	if res.StatusCode/100 != 2 {
 		azlog.Debug("Request failed", "status", res.Status, "body", string(body))
-		return AzureMonitorResponse{}, fmt.Errorf("Request failed status: %v", res.Status)
+		return AzureMonitorResponse{}, fmt.Errorf("request failed, status: %s", res.Status)
 	}
 
 	var data AzureMonitorResponse

pkg/tsdb/azuremonitor/azuremonitor.go

@@ -66,7 +66,7 @@ func (e *AzureMonitorExecutor) Query(ctx context.Context, dsInfo *models.DataSou
 		case "Insights Analytics":
 			insightsAnalyticsQueries = append(insightsAnalyticsQueries, query)
 		default:
-			return nil, fmt.Errorf("Alerting not supported for %s", queryType)
+			return nil, fmt.Errorf("alerting not supported for %q", queryType)
 		}
 	}
 

pkg/tsdb/azuremonitor/insights-analytics-datasource.go

@@ -139,7 +139,7 @@ func (e *InsightsAnalyticsDatasource) executeQuery(ctx context.Context, query *I
 
 	if res.StatusCode/100 != 2 {
 		azlog.Debug("Request failed", "status", res.Status, "body", string(body))
-		return queryResultError(fmt.Errorf("Request failed status: %v %w", res.Status, fmt.Errorf(string(body))))
+		return queryResultError(fmt.Errorf("request failed, status: %s, body: %s", res.Status, body))
 	}
 	var logResponse AzureLogAnalyticsResponse
 	d := json.NewDecoder(bytes.NewReader(body))
@@ -180,7 +180,7 @@ func (e *InsightsAnalyticsDatasource) createRequest(ctx context.Context, dsInfo
 	// find plugin
 	plugin, ok := plugins.DataSources[dsInfo.Type]
 	if !ok {
-		return nil, errors.New("Unable to find datasource plugin Azure Application Insights")
+		return nil, errors.New("unable to find datasource plugin Azure Application Insights")
 	}
 
 	cloudName := dsInfo.JsonData.Get("cloudName").MustString("azuremonitor")

pkg/tsdb/azuremonitor/macros.go

@@ -126,7 +126,7 @@ func (m *kqlMacroEngine) evaluateMacro(name string, defaultTimeField string, arg
 	case "escapeMulti":
 		return "", fmt.Errorf("escapeMulti macro not formatted correctly")
 	default:
-		return "", fmt.Errorf("Unknown macro %v", name)
+		return "", fmt.Errorf("unknown macro %q", name)
 	}
 }
 

pkg/tsdb/azuremonitor/time-grain.go

@@ -28,7 +28,7 @@ func (tg *TimeGrain) createISO8601DurationFromIntervalMS(interval int64) (string
 	timeValueString := formatted[0 : len(formatted)-1]
 	timeValue, err := strconv.Atoi(timeValueString)
 	if err != nil {
-		return "", fmt.Errorf("Could not parse interval %v to an ISO 8061 duration", interval)
+		return "", fmt.Errorf("could not parse interval %q to an ISO 8061 duration: %w", interval, err)
 	}
 
 	unit := formatted[len(formatted)-1:]

pkg/tsdb/cloudmonitoring/cloudmonitoring.go

@@ -103,7 +103,7 @@ func (e *CloudMonitoringExecutor) getGCEDefaultProject(ctx context.Context, tsdb
 
 	gceDefaultProject, err := e.getDefaultProject(ctx)
 	if err != nil {
-		return nil, fmt.Errorf("Failed to retrieve default project from GCE metadata server. error: %v", err)
+		return nil, fmt.Errorf("failed to retrieve default project from GCE metadata server, error: %w", err)
 	}
 
 	queryResult.Meta.Set("defaultProject", gceDefaultProject)
@@ -769,7 +769,7 @@ func (e *CloudMonitoringExecutor) createRequest(ctx context.Context, dsInfo *mod
 	req, err := http.NewRequest(http.MethodGet, "https://monitoring.googleapis.com/", nil)
 	if err != nil {
 		slog.Error("Failed to create request", "error", err)
-		return nil, fmt.Errorf("Failed to create request. error: %v", err)
+		return nil, fmt.Errorf("failed to create request: %w", err)
 	}
 
 	req.Header.Set("Content-Type", "application/json")
@@ -778,7 +778,7 @@ func (e *CloudMonitoringExecutor) createRequest(ctx context.Context, dsInfo *mod
 	// find plugin
 	plugin, ok := plugins.DataSources[dsInfo.Type]
 	if !ok {
-		return nil, errors.New("Unable to find datasource plugin CloudMonitoring")
+		return nil, errors.New("unable to find datasource plugin CloudMonitoring")
 	}
 
 	var cloudMonitoringRoute *plugins.AppPluginRoute
@@ -799,14 +799,14 @@ func (e *CloudMonitoringExecutor) getDefaultProject(ctx context.Context) (string
 	if authenticationType == gceAuthentication {
 		defaultCredentials, err := google.FindDefaultCredentials(ctx, "https://www.googleapis.com/auth/monitoring.read")
 		if err != nil {
-			return "", fmt.Errorf("Failed to retrieve default project from GCE metadata server. error: %v", err)
+			return "", fmt.Errorf("failed to retrieve default project from GCE metadata server: %w", err)
 		}
 		token, err := defaultCredentials.TokenSource.Token()
 		if err != nil {
-			return "", fmt.Errorf("Failed to retrieve GCP credential token. error: %v", err)
+			return "", fmt.Errorf("failed to retrieve GCP credential token: %w", err)
 		}
 		if !token.Valid() {
-			return "", errors.New("Failed to validate GCP credentials")
+			return "", errors.New("failed to validate GCP credentials")
 		}
 
 		return defaultCredentials.ProjectID, nil

pkg/tsdb/graphite/graphite.go

@@ -68,7 +68,7 @@ func (e *GraphiteExecutor) Query(ctx context.Context, dsInfo *models.DataSource,
 
 	if target == "" {
 		glog.Error("No targets in query model", "models without targets", strings.Join(emptyQueries, "\n"))
-		return nil, errors.New("No query target found for the alert rule")
+		return nil, errors.New("no query target found for the alert rule")
 	}
 
 	formData["target"] = []string{target}
@@ -140,7 +140,7 @@ func (e *GraphiteExecutor) parseResponse(res *http.Response) ([]TargetResponseDT
 
 	if res.StatusCode/100 != 2 {
 		glog.Info("Request failed", "status", res.Status, "body", string(body))
-		return nil, fmt.Errorf("Request failed status: %v", res.Status)
+		return nil, fmt.Errorf("request failed, status: %s", res.Status)
 	}
 
 	var data []TargetResponseDTO
@@ -163,7 +163,7 @@ func (e *GraphiteExecutor) createRequest(dsInfo *models.DataSource, data url.Val
 	req, err := http.NewRequest(http.MethodPost, u.String(), strings.NewReader(data.Encode()))
 	if err != nil {
 		glog.Info("Failed to create request", "error", err)
-		return nil, fmt.Errorf("Failed to create request. error: %v", err)
+		return nil, fmt.Errorf("failed to create request: %w", err)
 	}
 
 	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")

pkg/tsdb/influxdb/flux/builder.go

@@ -125,7 +125,7 @@ func (fb *frameBuilder) Init(metadata *query.FluxTableMetadata) error {
 		if col != nil {
 			fb.timeColumn = col.Name()
 			fb.timeDisplay = "Time"
-			if "_time" != fb.timeColumn {
+			if fb.timeColumn != "_time" {
 				fb.timeDisplay = col.Name()
 			}
 			return nil

pkg/tsdb/influxdb/influxdb.go

@@ -85,7 +85,7 @@ func (e *InfluxDBExecutor) Query(ctx context.Context, dsInfo *models.DataSource,
 
 	defer resp.Body.Close()
 	if resp.StatusCode/100 != 2 {
-		return nil, fmt.Errorf("Influxdb returned statuscode invalid status code: %v", resp.Status)
+		return nil, fmt.Errorf("InfluxDB returned statuscode invalid status code: %s", resp.Status)
 	}
 
 	var response Response

pkg/tsdb/mssql/macros.go

@@ -129,6 +129,6 @@ func (m *msSqlMacroEngine) evaluateMacro(name string, args []string) (string, er
 		}
 		return "", err
 	default:
-		return "", fmt.Errorf("Unknown macro %v", name)
+		return "", fmt.Errorf("unknown macro %q", name)
 	}
 }

pkg/tsdb/mysql/macros.go

@@ -35,7 +35,7 @@ func (m *mySqlMacroEngine) Interpolate(query *tsdb.Query, timeRange *tsdb.TimeRa
 	matches := restrictedRegExp.FindAllStringSubmatch(sql, 1)
 	if len(matches) > 0 {
 		m.logger.Error("show grants, session_user(), current_user(), system_user() or user() not allowed in query")
-		return "", errors.New("Invalid query. Inspect Grafana server log for details")
+		return "", errors.New("invalid query - inspect Grafana server log for details")
 	}
 
 	rExp, _ := regexp.Compile(sExpr)
@@ -135,6 +135,6 @@ func (m *mySqlMacroEngine) evaluateMacro(name string, args []string) (string, er
 		}
 		return "", err
 	default:
-		return "", fmt.Errorf("Unknown macro %v", name)
+		return "", fmt.Errorf("unknown macro %v", name)
 	}
 }

pkg/tsdb/mysql/macros_test.go

@@ -181,7 +181,7 @@ func TestMacroEngine(t *testing.T) {
 
 			for _, tc := range tcs {
 				_, err := engine.Interpolate(nil, nil, tc)
-				So(err.Error(), ShouldEqual, "Invalid query. Inspect Grafana server log for details")
+				So(err.Error(), ShouldEqual, "invalid query - inspect Grafana server log for details")
 			}
 		})
 	})

pkg/tsdb/mysql/mysql.go

@@ -150,4 +150,4 @@ func (t *mysqlQueryResultTransformer) TransformQueryError(err error) error {
 	return err
 }
 
-var errQueryFailed = errors.New("Query failed. Please inspect Grafana server log for details")
+var errQueryFailed = errors.New("query failed - please inspect Grafana server log for details")

pkg/tsdb/opentsdb/opentsdb.go

@@ -88,13 +88,13 @@ func (e *OpenTsdbExecutor) createRequest(dsInfo *models.DataSource, data OpenTsd
 	postData, err := json.Marshal(data)
 	if err != nil {
 		plog.Info("Failed marshaling data", "error", err)
-		return nil, fmt.Errorf("Failed to create request. error: %v", err)
+		return nil, fmt.Errorf("failed to create request: %w", err)
 	}
 
 	req, err := http.NewRequest(http.MethodPost, u.String(), strings.NewReader(string(postData)))
 	if err != nil {
 		plog.Info("Failed to create request", "error", err)
-		return nil, fmt.Errorf("Failed to create request. error: %v", err)
+		return nil, fmt.Errorf("failed to create request: %w", err)
 	}
 
 	req.Header.Set("Content-Type", "application/json")
@@ -117,7 +117,7 @@ func (e *OpenTsdbExecutor) parseResponse(query OpenTsdbQuery, res *http.Response
 
 	if res.StatusCode/100 != 2 {
 		plog.Info("Request failed", "status", res.Status, "body", string(body))
-		return nil, fmt.Errorf("Request failed status: %v", res.Status)
+		return nil, fmt.Errorf("request failed, status: %s", res.Status)
 	}
 
 	var data []OpenTsdbResponse

pkg/tsdb/postgres/macros.go

@@ -159,6 +159,6 @@ func (m *postgresMacroEngine) evaluateMacro(name string, args []string) (string,
 		}
 		return "", err
 	default:
-		return "", fmt.Errorf("Unknown macro %v", name)
+		return "", fmt.Errorf("unknown macro %q", name)
 	}
 }

pkg/tsdb/prometheus/prometheus.go

@@ -193,7 +193,7 @@ func parseResponse(value model.Value, query *PrometheusQuery) (*tsdb.QueryResult
 
 	data, ok := value.(model.Matrix)
 	if !ok {
-		return queryRes, fmt.Errorf("Unsupported result format: %s", value.Type().String())
+		return queryRes, fmt.Errorf("unsupported result format: %q", value.Type().String())
 	}
 
 	for _, v := range data {

pkg/tsdb/sqleng/sql_engine.go

@@ -343,7 +343,7 @@ func (e *sqlQueryEndpoint) transformToTimeSeries(query *tsdb.Query, rows *core.R
 	}
 
 	if cfg.timeIndex == -1 {
-		return fmt.Errorf("Found no column named %s", strings.Join(e.timeColumnNames, " or "))
+		return fmt.Errorf("found no column named %q", strings.Join(e.timeColumnNames, " or "))
 	}
 
 	if cfg.fillMissing {
@@ -666,7 +666,10 @@ func ConvertSqlValueColumnToFloat(columnName string, columnValue interface{}) (n
 	case nil:
 		value.Valid = false
 	default:
-		return null.NewFloat(0, false), fmt.Errorf("Value column must have numeric datatype, column: %s type: %T value: %v", columnName, typedValue, typedValue)
+		return null.NewFloat(0, false), fmt.Errorf(
+			"value column must have numeric datatype, column: %s, type: %T, value: %v",
+			columnName, typedValue, typedValue,
+		)
 	}
 
 	return value, nil

pkg/util/encoding.go

@@ -57,7 +57,7 @@ func DecodeBasicAuthHeader(header string) (string, string, error) {
 
 	userAndPass := strings.SplitN(string(decoded), ":", 2)
 	if len(userAndPass) != 2 {
-		return "", "", errors.New("Invalid basic auth header")
+		return "", "", errors.New("invalid basic auth header")
 	}
 
 	return userAndPass[0], userAndPass[1], nil

pkg/util/filepath.go

@@ -63,7 +63,7 @@ func walk(path string, info os.FileInfo, resolvedPath string, symlinkPathsFollow
 		// vout("SymLink Path: %v, links to: %v", resolvedPath, path2)
 		if symlinkPathsFollowed != nil {
 			if _, ok := symlinkPathsFollowed[path2]; ok {
-				errMsg := "Potential SymLink Infinite Loop. Path: %v, Link To: %v"
+				errMsg := "potential symLink infinite loop, path: %v, link to: %v"
 				return fmt.Errorf(errMsg, resolvedPath, path2)
 			}
 			symlinkPathsFollowed[path2] = true

pkg/util/ip_address.go

@@ -53,7 +53,7 @@ func SplitHostPortDefault(input, defaultHost, defaultPort string) (NetworkAddres
 		addrEnd := strings.LastIndex(input, "]")
 		if addrEnd < 0 {
 			// Malformed address
-			return addr, fmt.Errorf("Malformed IPv6 address: '%s'", input)
+			return addr, fmt.Errorf("malformed IPv6 address: '%s'", input)
 		}
 
 		start = addrEnd
@@ -83,7 +83,7 @@ func SplitHostPortDefault(input, defaultHost, defaultPort string) (NetworkAddres
 // SplitHostPort splits ip address/hostname string by host and port
 func SplitHostPort(input string) (NetworkAddress, error) {
 	if len(input) == 0 {
-		return NetworkAddress{}, fmt.Errorf("Input is empty")
+		return NetworkAddress{}, fmt.Errorf("input is empty")
 	}
 	return SplitHostPortDefault(input, "", "")
 }

pkg/util/ip_address_test.go

@@ -32,7 +32,7 @@ func TestParseIPAddress_Invalid(t *testing.T) {
 	}{
 		{
 			input: "[::1",
-			err:   "failed to split network address \"[::1\" by host and port: Malformed IPv6 address: '[::1'",
+			err:   "failed to split network address \"[::1\" by host and port: malformed IPv6 address: '[::1'",
 		},
 		{
 			input: "::1]",
@@ -40,7 +40,7 @@ func TestParseIPAddress_Invalid(t *testing.T) {
 		},
 		{
 			input: "",
-			err:   "failed to split network address \"\" by host and port: Input is empty",
+			err:   "failed to split network address \"\" by host and port: input is empty",
 		},
 	}
 	for _, testcase := range tests {