fix: updated go version for dockerfile to build controller

Also centralized the preferred and minimum version variables into a version file
in utils package to assist with future upgrades.

Signed-off-by: Dustin Scott <dustin.scott18@gmail.com>

internal/plugins/workload/v1/scaffolds/templates/dockerfile.go

@@ -5,6 +5,8 @@ package templates
 
 import (
 	"sigs.k8s.io/kubebuilder/v3/pkg/machinery"
+
+	"github.com/vmware-tanzu-labs/operator-builder/internal/utils"
 )
 
 const (
@@ -16,6 +18,8 @@ var _ machinery.Template = &Dockerfile{}
 // Dockerfile scaffolds a file that defines the containerized build process.
 type Dockerfile struct {
 	machinery.TemplateMixin
+
+	GoVersion string
 }
 
 // SetTemplateDefaults implements file.Template.
@@ -24,15 +28,15 @@ func (f *Dockerfile) SetTemplateDefaults() error {
 		f.Path = defaultDockerfilePath
 	}
 
+	f.GoVersion = utils.GeneratedGoVersionPreferred
 	f.IfExistsAction = machinery.OverwriteFile
-
 	f.TemplateBody = dockerfileTemplate
 
 	return nil
 }
 
 const dockerfileTemplate = `# Build the manager binary
-FROM golang:1.16 as builder
+FROM golang:{{ .GoVersion }} as builder
 
 WORKDIR /workspace
 # Copy the Go Modules manifests

internal/plugins/workload/v1/scaffolds/templates/gomod.go

@@ -5,14 +5,12 @@ package templates
 
 import (
 	"sigs.k8s.io/kubebuilder/v3/pkg/machinery"
+
+	"github.com/vmware-tanzu-labs/operator-builder/internal/utils"
 )
 
 var _ machinery.Template = &GoMod{}
 
-const (
-	GoVersionMinimum = "1.17"
-)
-
 // GoMod scaffolds a file that defines the project dependencies.
 type GoMod struct {
 	machinery.TemplateMixin
@@ -57,7 +55,7 @@ func (f *GoMod) SetTemplateDefaults() error {
 		f.Path = "go.mod"
 	}
 
-	f.GoVersionMinimum = GoVersionMinimum
+	f.GoVersionMinimum = utils.GeneratedGoVersionMinimum
 	f.Dependencies = goModDependencyMap()
 	f.IndirectDependencies = goModIndirectDependencyMap()
 	f.TemplateBody = goModTemplate

internal/utils/version.go

@@ -0,0 +1,9 @@
+package utils
+
+const (
+	// specifies the minimum version required to build the generated project
+	GeneratedGoVersionMinimum = "1.17"
+
+	// specifies the preferred version
+	GeneratedGoVersionPreferred = "1.18"
+)