Fix JMX nil pointer

Makefile

@@ -3,7 +3,7 @@ GO_VERSION = $(shell go version | sed 's/[^0-9.]*\([0-9.]*\).*/\1/')
 GOTOOLS = github.com/axw/gocov/gocov \
           github.com/AlekSi/gocov-xml
 
-GOLANGCILINT_VERSION = v1.24.0
+GOLANGCILINT_VERSION = v1.56.0
 GOLANGCILINT_BIN = bin/golangci-lint
 
 # Temporary patch to avoid build failing because of the outdated documentation example
@@ -24,7 +24,7 @@ bin:
 .PHONY: tools/golangci-lint
 tools/golangci-lint:
 	@echo "installing GolangCI lint"
-	@(wget -qO - https://install.goreleaser.com/github.com/golangci/golangci-lint.sh | sh -s $(GOLANGCILINT_VERSION) )
+	@(wget -qO - https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s $(GOLANGCILINT_VERSION) )
 
 
 .PHONY: tools

args/args.go

@@ -80,12 +80,12 @@ func underscore(s string) string {
 // fields it defines. Each of the fields in the struct can define their defaults
 // and help string by using tags:
 //
-//  type Arguments struct {
-//     	DefaultArgumentList
-//     	Argument1 bool   `default:"false" help:"This is the help we will print"`
-//     	Argument2 int    `default:"1" help:"This is the help we will print"`
-//     	Argument3 string `default:"value" help:"This is the help we will print"`
-//  }
+//	type Arguments struct {
+//	   	DefaultArgumentList
+//	   	Argument1 bool   `default:"false" help:"This is the help we will print"`
+//	   	Argument2 int    `default:"1" help:"This is the help we will print"`
+//	   	Argument3 string `default:"value" help:"This is the help we will print"`
+//	}
 //
 // The fields in the struct will be populated with the values set either from
 // the command line or from environment variables.

docs/tutorial-code-v3/multiple-entities/redis.go

@@ -54,6 +54,7 @@ func queryAttrRedisInfo(query string, port int) (string, string) {
 	return strings.TrimSpace(splittedLine[0]), strings.TrimSpace(splittedLine[1])
 }
 
+// nolint: typecheck
 func main() {
 	// Create Integration
 	i, err := integration.New(integrationName, integrationVersion, integration.Args(&args))

docs/tutorial-code-v3/single-entity/redis.go

@@ -48,6 +48,7 @@ func queryRedisConfig(query string) (string, string) {
 	return splittedLine[0], splittedLine[1]
 }
 
+// nolint: typecheck
 func main() {
 	// Create Integration
 	i, err := integration.New(integrationName, integrationVersion, integration.Args(&args))

integration/integration_test.go

@@ -585,7 +585,7 @@ func Test_Integration_FindEntity(t *testing.T) {
 	assert.True(t, e.SameAs(e1))
 }
 
-//--- helpers
+// --- helpers
 func newTestIntegration(t *testing.T) *Integration {
 	i, err := New(integrationName, integrationVersion, Logger(log.Discard), Writer(ioutil.Discard))
 	assert.NoError(t, err)

jmx/jmx.go

@@ -1,7 +1,8 @@
 /*
 Package jmx is a library to get metrics through JMX. It requires additional
 setup. Read https://github.com/newrelic/infra-integrations-sdk#jmx-support for
-instructions. */
+instructions.
+*/
 package jmx
 
 import (
@@ -236,8 +237,10 @@ func openConnection(config *connectionConfig) (err error) {
 	}
 
 	go func() {
-		if err = cmd.Wait(); err != nil {
-			cmdErrC <- jmxClientError(fmt.Sprintf("nrjmx error: %s [proc-state: %s]", err, cmd.ProcessState))
+		if cmd != nil {
+			if err = cmd.Wait(); err != nil {
+				cmdErrC <- jmxClientError(fmt.Sprintf("nrjmx error: %s [proc-state: %s]", err, cmd.ProcessState))
+			}
 		}
 
 		cmd = nil

jmx/jmx_test.go

@@ -92,6 +92,7 @@ func TestOpenURL(t *testing.T) {
 	assert.Equal(t, "sample.url", lastArg)
 }
 
+// nolint: goconst
 func TestQuery(t *testing.T) {
 	for q, isErr := range query2IsErr {
 		require.NoError(t, openWait("", "", "", "", openAttempts), "error on opening for query %s", q)

jmx/jmx_unix.go

@@ -1,9 +1,11 @@
+//go:build linux || darwin
 // +build linux darwin
 
 /*
 Package jmx is a library to get metrics through JMX. It requires additional
 setup. Read https://github.com/newrelic/infra-integrations-sdk#jmx-support for
-instructions. */
+instructions.
+*/
 package jmx
 
 const (