Fix linter errors

Multiple: "io/ioutil" has been deprecated since Go 1.16: As of Go 1.16,
the same functionality is now provided by package io or package os, and
those implementations should be preferred in new code. See the specific
function documentation for details.  (SA1019)

discovery/consul_test.go:163:11: unnecessary use of fmt.Sprintf (S1039)

config/config.go

@@ -6,7 +6,7 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
-	"io/ioutil"
+	"os"
 	"strings"
 
 	"github.com/flynn/json5"
@@ -79,7 +79,7 @@ func RenderConfig(configFlag, renderFlag string) error {
 		fmt.Printf("%s", renderedConfig)
 	} else {
 		var err error
-		if err = ioutil.WriteFile(renderFlag, renderedConfig, 0644); err != nil {
+		if err = os.WriteFile(renderFlag, renderedConfig, 0644); err != nil {
 			return fmt.Errorf("could not write config file: %s", err)
 		}
 	}
@@ -108,7 +108,7 @@ func loadConfigFile(configFlag string) ([]byte, error) {
 	if configFlag == "" {
 		return nil, errors.New("-config flag is required")
 	}
-	data, err := ioutil.ReadFile(configFlag)
+	data, err := os.ReadFile(configFlag)
 	if err != nil {
 		return nil, fmt.Errorf("could not read config file: %s", err)
 	}

config/config_test.go

@@ -1,7 +1,6 @@
 package config
 
 import (
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
@@ -185,8 +184,8 @@ func TestRenderConfigFileStdout(t *testing.T) {
 	temp.Close()
 	os.Stdout = old
 
-	renderedOut, _ := ioutil.ReadFile(fname)
-	renderedFile, _ := ioutil.ReadFile("testJSON.json")
+	renderedOut, _ := os.ReadFile(fname)
+	renderedFile, _ := os.ReadFile("testJSON.json")
 	if string(renderedOut) != string(renderedFile) {
 		t.Fatalf("expected the rendered file and stdout to be identical")
 	}

config/logger/logging_test.go

@@ -1,7 +1,6 @@
 package logger
 
 import (
-	"io/ioutil"
 	"os"
 	"reflect"
 	"strings"
@@ -84,7 +83,7 @@ func TestFileLogger(t *testing.T) {
 	// write a log message
 	logMsg := "this is a test"
 	logrus.Info(logMsg)
-	content, err := ioutil.ReadFile(filename)
+	content, err := os.ReadFile(filename)
 	if err != nil {
 		t.Errorf("Did not expect error: %v", err)
 	}

control/endpoints.go

@@ -5,7 +5,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"net/http"
 	"os"
 	"strconv"
@@ -56,7 +55,7 @@ func (pw PostHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 // process. Returns empty response or HTTP422.
 func (e Endpoints) PutEnviron(r *http.Request) (interface{}, int) {
 	var postEnv map[string]string
-	jsonBlob, err := ioutil.ReadAll(r.Body)
+	jsonBlob, err := io.ReadAll(r.Body)
 	defer r.Body.Close()
 	if err != nil {
 		return nil, http.StatusUnprocessableEntity
@@ -110,7 +109,7 @@ func (e Endpoints) PostDisableMaintenanceMode(r *http.Request) (interface{}, int
 // Returns empty response or HTTP422.
 func (e Endpoints) PostMetric(r *http.Request) (interface{}, int) {
 	var postMetrics map[string]interface{}
-	jsonBlob, err := ioutil.ReadAll(r.Body)
+	jsonBlob, err := io.ReadAll(r.Body)
 
 	defer r.Body.Close()
 	if err != nil {

control/endpoints_test.go

@@ -3,7 +3,7 @@ package control
 import (
 	"context"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"net/http/httptest"
 	"os"
@@ -65,7 +65,7 @@ func TestPostHandler(t *testing.T) {
 		ph.ServeHTTP(w, req)
 		resp := w.Result()
 		defer resp.Body.Close()
-		body, _ := ioutil.ReadAll(resp.Body)
+		body, _ := io.ReadAll(resp.Body)
 		status := resp.StatusCode
 		return status, string(body)
 	}

core/app_test.go

@@ -2,7 +2,6 @@ package core
 
 import (
 	"fmt"
-	"io/ioutil"
 	"os"
 	"strings"
 	"testing"
@@ -152,7 +151,7 @@ func TestReloadConfig(t *testing.T) {
 // write the configuration to a tempfile. caller is responsible
 // for calling 'defer os.Remove(f.Name())' when done
 func testCfgToTempFile(t *testing.T, text string) *os.File {
-	f, err := ioutil.TempFile(".", "test-")
+	f, err := os.CreateTemp(".", "test-")
 	if err != nil {
 		t.Fatal(err)
 	}

jobs/config_test.go

@@ -2,7 +2,7 @@ package jobs
 
 import (
 	"fmt"
-	"io/ioutil"
+	"os"
 	"testing"
 	"time"
 
@@ -167,7 +167,7 @@ func TestJobConfigConsulExtras(t *testing.T) {
 }
 
 func TestJobConfigSmokeTest(t *testing.T) {
-	data, _ := ioutil.ReadFile(fmt.Sprintf("./testdata/%s.json5", t.Name()))
+	data, _ := os.ReadFile(fmt.Sprintf("./testdata/%s.json5", t.Name()))
 	testCfg := tests.DecodeRawToSlice(string(data))
 	assert := assert.New(t)
 
@@ -287,15 +287,15 @@ func TestJobConfigValidateDiscovery(t *testing.T) {
 }
 
 func TestErrJobConfigConsulEnableTagOverride(t *testing.T) {
-	testCfg, _ := ioutil.ReadFile(fmt.Sprintf("./testdata/%s.json5", t.Name()))
+	testCfg, _ := os.ReadFile(fmt.Sprintf("./testdata/%s.json5", t.Name()))
 	_, err := NewConfigs(tests.DecodeRawToSlice(string(testCfg)), noop)
 	if err == nil {
 		t.Errorf("ConsulExtras should have thrown error about EnableTagOverride being a string.")
 	}
 }
 
 func TestErrJobConfigConsulDeregisterCriticalServiceAfter(t *testing.T) {
-	testCfg, _ := ioutil.ReadFile(fmt.Sprintf("./testdata/%s.json5", t.Name()))
+	testCfg, _ := os.ReadFile(fmt.Sprintf("./testdata/%s.json5", t.Name()))
 	_, err := NewConfigs(tests.DecodeRawToSlice(string(testCfg)), noop)
 	if err == nil {
 		t.Errorf("error should have been generated for duration 'nope'.")
@@ -471,7 +471,7 @@ func TestHealthChecksConfigError(t *testing.T) {
 var noop = &mocks.NoopDiscoveryBackend{}
 
 func loadTestConfig(t *testing.T) []*Config {
-	data, _ := ioutil.ReadFile(fmt.Sprintf("./testdata/%s.json5", t.Name()))
+	data, _ := os.ReadFile(fmt.Sprintf("./testdata/%s.json5", t.Name()))
 	testCfg := tests.DecodeRawToSlice(string(data))
 
 	jobs, err := NewConfigs(testCfg, noop)

telemetry/metrics_test.go

@@ -3,7 +3,7 @@ package telemetry
 import (
 	"context"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"net/http/httptest"
 	"reflect"
@@ -270,7 +270,7 @@ func getFromTestServer(t *testing.T, testServer *httptest.Server) string {
 		t.Fatal(err)
 	} else {
 		defer res.Body.Close()
-		if resp, err := ioutil.ReadAll(res.Body); err != nil {
+		if resp, err := io.ReadAll(res.Body); err != nil {
 			t.Fatal(err)
 		} else {
 			response := string(resp)

telemetry/telemetry_config_test.go

@@ -2,7 +2,7 @@ package telemetry
 
 import (
 	"fmt"
-	"io/ioutil"
+	"os"
 	"strings"
 	"testing"
 
@@ -13,7 +13,7 @@ import (
 )
 
 func TestTelemetryConfigParse(t *testing.T) {
-	data, _ := ioutil.ReadFile(fmt.Sprintf("./testdata/%s.json5", t.Name()))
+	data, _ := os.ReadFile(fmt.Sprintf("./testdata/%s.json5", t.Name()))
 	testCfg := tests.DecodeRaw(string(data))
 	telem, err := NewConfig(testCfg, &mocks.NoopDiscoveryBackend{})
 	if err != nil {

watches/config_test.go

@@ -2,7 +2,7 @@ package watches
 
 import (
 	"fmt"
-	"io/ioutil"
+	"os"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -11,7 +11,7 @@ import (
 )
 
 func TestWatchesParse(t *testing.T) {
-	data, _ := ioutil.ReadFile(fmt.Sprintf("./testdata/%s.json5", t.Name()))
+	data, _ := os.ReadFile(fmt.Sprintf("./testdata/%s.json5", t.Name()))
 	testCfg := tests.DecodeRawToSlice(string(data))
 	watches, err := NewConfigs(testCfg, nil)
 	if err != nil {