Bump up min Go version to 1.20 and other dependent changes (#228)

controller-runtime v15 has a min Golang version requirement that
breaks the container builds. This change bumps up the Go version used
to build the container. Starting 1.21 Golang, go.mod requires the Go
version and treats that as min required go version to compile your
binary. So, also bump up the Go version for local builds.

Additional changes:

- As per golang/go#56319
and golang/go#54880, global rand is
automatically, randomly seeded. So we don't need to call `Seed`
anymore.

- Package ioutil has been deprecated. Port the code to use replacement
methods.

.github/workflows/ci.yml

@@ -1,7 +1,7 @@
 name: ci
 
 env:
-  GO_VERSION: 1.19.3
+  GO_VERSION: 1.20.0
 
 on:
   pull_request:

Dockerfile

@@ -1,5 +1,5 @@
 # Go version used to build the binaries.
-ARG GO_VERSION=1.18.4
+ARG GO_VERSION=1.20
 
 ## Docker image used to build the binaries.
 FROM golang:${GO_VERSION} as builder

go.mod

@@ -1,6 +1,6 @@
 module github.com/vmware-tanzu/vm-operator
 
-go 1.18
+go 1.20
 
 replace (
 	github.com/envoyproxy/go-control-plane => github.com/envoyproxy/go-control-plane v0.9.4

main.go

@@ -6,7 +6,6 @@ package main
 import (
 	"crypto/tls"
 	"flag"
-	"math/rand"
 	"net/http"
 	"net/http/pprof"
 	"os"
@@ -119,8 +118,6 @@ func main() {
 	setupLog.Info("Starting VM Operator controller", "version", pkg.BuildVersion,
 		"buildnumber", pkg.BuildNumber, "buildtype", pkg.BuildType, "commit", pkg.BuildCommit)
 
-	rand.Seed(time.Now().UnixNano())
-
 	profilerAddress := flag.String(
 		"profiler-address",
 		defaultProfilerAddr,

pkg/util/enc_test.go

@@ -7,7 +7,7 @@ import (
 	"bytes"
 	"compress/gzip"
 	"encoding/base64"
-	"io/ioutil"
+	"io"
 
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
@@ -170,7 +170,7 @@ var _ = Describe("EncodeGzipBase64", func() {
 		Expect(err).NotTo(HaveOccurred())
 		defer Expect(gzipReader.Close()).To(Succeed())
 
-		ungzipped, err := ioutil.ReadAll(gzipReader)
+		ungzipped, err := io.ReadAll(gzipReader)
 		Expect(err).NotTo(HaveOccurred())
 		Expect(input).Should(Equal(string(ungzipped)))
 	})

test/builder/util.go

@@ -12,7 +12,7 @@ import (
 	"encoding/pem"
 	"fmt"
 	"io"
-	"io/ioutil"
+	"os"
 	"path/filepath"
 
 	"github.com/google/uuid"
@@ -604,7 +604,7 @@ func indexOfVersion(
 
 func LoadCRDs(rootFilePath string) ([]*apiextensionsv1.CustomResourceDefinition, error) {
 	// Read the CRD files.
-	files, err := ioutil.ReadDir(rootFilePath)
+	files, err := os.ReadDir(rootFilePath)
 	if err != nil {
 		return nil, err
 	}
@@ -641,7 +641,7 @@ func LoadCRDs(rootFilePath string) ([]*apiextensionsv1.CustomResourceDefinition,
 // copied from https://github.com/kubernetes-sigs/controller-runtime/blob/5bf44d2ffd6201703508e11fbae74fcedc5ce148/pkg/envtest/crd.go#L434-L458
 func readDocuments(fp string) ([][]byte, error) {
 	//nolint:gosec
-	b, err := ioutil.ReadFile(fp)
+	b, err := os.ReadFile(fp)
 	if err != nil {
 		return nil, err
 	}