Don't use globals for platforms and components registration

cli/cmd/cluster/cluster.go

@@ -27,22 +27,11 @@ import (
 	"sigs.k8s.io/yaml"
 
 	"github.com/kinvolk/lokomotive/pkg/assets"
-	"github.com/kinvolk/lokomotive/pkg/backend"
 	"github.com/kinvolk/lokomotive/pkg/backend/local"
 	"github.com/kinvolk/lokomotive/pkg/components/util"
 	"github.com/kinvolk/lokomotive/pkg/config"
 	"github.com/kinvolk/lokomotive/pkg/platform"
 	"github.com/kinvolk/lokomotive/pkg/terraform"
-
-	// Register platforms by adding an anonymous import.
-	_ "github.com/kinvolk/lokomotive/pkg/platform/aks"
-	_ "github.com/kinvolk/lokomotive/pkg/platform/aws"
-	_ "github.com/kinvolk/lokomotive/pkg/platform/baremetal"
-	_ "github.com/kinvolk/lokomotive/pkg/platform/packet"
-	_ "github.com/kinvolk/lokomotive/pkg/platform/tinkerbell"
-
-	// Register backends by adding an anonymous import.
-	_ "github.com/kinvolk/lokomotive/pkg/backend/s3"
 )
 
 // cluster is a temporary helper struct to aggregate objects which are used
@@ -89,7 +78,7 @@ func (cc clusterConfig) initialize(contextLogger *log.Entry) (*cluster, error) {
 
 	// Use a local backend if no backend is configured.
 	if b == nil {
-		b = local.NewLocalBackend()
+		b = local.NewConfig()
 	}
 
 	assetDir, err := homedir.Expand(p.Meta().AssetDir)
@@ -132,7 +121,7 @@ func (c *cluster) unpackControlplaneCharts() error {
 
 // initializeTerraform initialized Terraform directory using given backend and platform
 // and returns configured executor.
-func (cc clusterConfig) initializeTerraform(p platform.Platform, b backend.Backend) (*terraform.Executor, error) {
+func (cc clusterConfig) initializeTerraform(p platform.Platform, b backend) (*terraform.Executor, error) {
 	assetDir, err := homedir.Expand(p.Meta().AssetDir)
 	if err != nil {
 		return nil, fmt.Errorf("expanding path %q: %w", p.Meta().AssetDir, err)

cli/cmd/cluster/component-delete.go

@@ -103,7 +103,7 @@ func componentNamesToObjects(componentNames []string) ([]components.Component, e
 	c := []components.Component{}
 
 	for _, componentName := range componentNames {
-		component, err := components.Get(componentName)
+		component, err := componentConfig(componentName)
 		if err != nil {
 			return nil, fmt.Errorf("getting component %q: %w", componentName, err)
 		}

cli/cmd/cluster/component-render-manifest.go

@@ -19,7 +19,6 @@ import (
 
 	log "github.com/sirupsen/logrus"
 
-	"github.com/kinvolk/lokomotive/pkg/components"
 	"github.com/kinvolk/lokomotive/pkg/config"
 )
 
@@ -57,7 +56,7 @@ func renderComponentManifests(lokoConfig *config.Config, componentNames []string
 			"component": componentName,
 		})
 
-		component, err := components.Get(componentName)
+		component, err := componentConfig(componentName)
 		if err != nil {
 			return fmt.Errorf("getting component %q: %w", componentName, err)
 		}

cli/cmd/cluster/component.go

@@ -15,33 +15,74 @@
 package cluster
 
 import (
-	// Register a component by adding an anonymous import.
-	_ "github.com/kinvolk/lokomotive/pkg/components/aws-ebs-csi-driver"
-	_ "github.com/kinvolk/lokomotive/pkg/components/cert-manager"
-	_ "github.com/kinvolk/lokomotive/pkg/components/cluster-autoscaler"
-	_ "github.com/kinvolk/lokomotive/pkg/components/contour"
-	_ "github.com/kinvolk/lokomotive/pkg/components/dex"
-	_ "github.com/kinvolk/lokomotive/pkg/components/external-dns"
-	_ "github.com/kinvolk/lokomotive/pkg/components/flatcar-linux-update-operator"
-	_ "github.com/kinvolk/lokomotive/pkg/components/gangway"
-	_ "github.com/kinvolk/lokomotive/pkg/components/httpbin"
-	_ "github.com/kinvolk/lokomotive/pkg/components/inspektor-gadget"
-	_ "github.com/kinvolk/lokomotive/pkg/components/istio-operator"
-	_ "github.com/kinvolk/lokomotive/pkg/components/linkerd"
-	_ "github.com/kinvolk/lokomotive/pkg/components/metallb"
-	_ "github.com/kinvolk/lokomotive/pkg/components/metrics-server"
-	_ "github.com/kinvolk/lokomotive/pkg/components/openebs-operator"
-	_ "github.com/kinvolk/lokomotive/pkg/components/openebs-storage-class"
-	_ "github.com/kinvolk/lokomotive/pkg/components/prometheus-operator"
-	_ "github.com/kinvolk/lokomotive/pkg/components/rook"
-	_ "github.com/kinvolk/lokomotive/pkg/components/rook-ceph"
-	_ "github.com/kinvolk/lokomotive/pkg/components/velero"
-	_ "github.com/kinvolk/lokomotive/pkg/components/web-ui"
+	"fmt"
 
 	"github.com/kinvolk/lokomotive/pkg/components"
+	awsebscsidriver "github.com/kinvolk/lokomotive/pkg/components/aws-ebs-csi-driver"
+	certmanager "github.com/kinvolk/lokomotive/pkg/components/cert-manager"
+	clusterautoscaler "github.com/kinvolk/lokomotive/pkg/components/cluster-autoscaler"
+	"github.com/kinvolk/lokomotive/pkg/components/contour"
+	"github.com/kinvolk/lokomotive/pkg/components/dex"
+	externaldns "github.com/kinvolk/lokomotive/pkg/components/external-dns"
+	flatcarlinuxupdateoperator "github.com/kinvolk/lokomotive/pkg/components/flatcar-linux-update-operator"
+	"github.com/kinvolk/lokomotive/pkg/components/gangway"
+	"github.com/kinvolk/lokomotive/pkg/components/httpbin"
+	inspektorgadget "github.com/kinvolk/lokomotive/pkg/components/inspektor-gadget"
+	istiooperator "github.com/kinvolk/lokomotive/pkg/components/istio-operator"
+	"github.com/kinvolk/lokomotive/pkg/components/linkerd"
+	"github.com/kinvolk/lokomotive/pkg/components/metallb"
+	metricsserver "github.com/kinvolk/lokomotive/pkg/components/metrics-server"
+	openebsoperator "github.com/kinvolk/lokomotive/pkg/components/openebs-operator"
+	openebsstorageclass "github.com/kinvolk/lokomotive/pkg/components/openebs-storage-class"
+	"github.com/kinvolk/lokomotive/pkg/components/prometheus-operator"
+	"github.com/kinvolk/lokomotive/pkg/components/rook"
+	rookceph "github.com/kinvolk/lokomotive/pkg/components/rook-ceph"
+	"github.com/kinvolk/lokomotive/pkg/components/velero"
+	webui "github.com/kinvolk/lokomotive/pkg/components/web-ui"
 )
 
+func componentsConfigs() map[string]components.Component {
+	return map[string]components.Component{
+		awsebscsidriver.Name:            awsebscsidriver.NewConfig(),
+		certmanager.Name:                certmanager.NewConfig(),
+		clusterautoscaler.Name:          clusterautoscaler.NewConfig(),
+		contour.Name:                    contour.NewConfig(),
+		dex.Name:                        dex.NewConfig(),
+		externaldns.Name:                externaldns.NewConfig(),
+		flatcarlinuxupdateoperator.Name: flatcarlinuxupdateoperator.NewConfig(),
+		gangway.Name:                    gangway.NewConfig(),
+		httpbin.Name:                    httpbin.NewConfig(),
+		inspektorgadget.Name:            inspektorgadget.NewConfig(),
+		istiooperator.Name:              istiooperator.NewConfig(),
+		linkerd.Name:                    linkerd.NewConfig(),
+		metallb.Name:                    metallb.NewConfig(),
+		metricsserver.Name:              metricsserver.NewConfig(),
+		openebsoperator.Name:            openebsoperator.NewConfig(),
+		openebsstorageclass.Name:        openebsstorageclass.NewConfig(),
+		prometheus.Name:                 prometheus.NewConfig(),
+		rook.Name:                       rook.NewConfig(),
+		rookceph.Name:                   rookceph.NewConfig(),
+		velero.Name:                     velero.NewConfig(),
+		webui.Name:                      webui.NewConfig(),
+	}
+}
+
 // AvailableComponents returns list of valid component names.
 func AvailableComponents() []string {
-	return components.ListNames()
+	c := []string{}
+
+	for n := range componentsConfigs() {
+		c = append(c, n)
+	}
+
+	return c
+}
+
+func componentConfig(name string) (components.Component, error) {
+	c, ok := componentsConfigs()[name]
+	if !ok {
+		return nil, fmt.Errorf("no component with name %q found", name)
+	}
+
+	return c, nil
 }

cli/cmd/cluster/utils.go

@@ -24,9 +24,15 @@ import (
 	"github.com/mitchellh/go-homedir"
 	log "github.com/sirupsen/logrus"
 
-	"github.com/kinvolk/lokomotive/pkg/backend"
+	"github.com/kinvolk/lokomotive/pkg/backend/local"
+	"github.com/kinvolk/lokomotive/pkg/backend/s3"
 	"github.com/kinvolk/lokomotive/pkg/config"
 	"github.com/kinvolk/lokomotive/pkg/platform"
+	"github.com/kinvolk/lokomotive/pkg/platform/aks"
+	"github.com/kinvolk/lokomotive/pkg/platform/aws"
+	"github.com/kinvolk/lokomotive/pkg/platform/baremetal"
+	"github.com/kinvolk/lokomotive/pkg/platform/packet"
+	"github.com/kinvolk/lokomotive/pkg/platform/tinkerbell"
 )
 
 const (
@@ -35,25 +41,56 @@ const (
 	kubeconfigTerraformOutputKey = "kubeconfig"
 )
 
+// backend describes the Terraform state storage location.
+type backend interface {
+	// LoadConfig loads the backend config provided by the user.
+	LoadConfig(*hcl.Body, *hcl.EvalContext) hcl.Diagnostics
+	// Render renders the backend template with user backend configuration.
+	Render() (string, error)
+	// Validate validates backend configuration.
+	Validate() error
+}
+
 // getConfiguredBackend loads a backend from the given configuration file.
-func getConfiguredBackend(lokoConfig *config.Config) (backend.Backend, hcl.Diagnostics) {
+func getConfiguredBackend(lokoConfig *config.Config) (backend, hcl.Diagnostics) {
 	if lokoConfig.RootConfig.Backend == nil {
 		// No backend defined and no configuration error
 		return nil, hcl.Diagnostics{}
 	}
 
-	backend, err := backend.GetBackend(lokoConfig.RootConfig.Backend.Name)
-	if err != nil {
+	backends := map[string]backend{
+		s3.Name:    s3.NewConfig(),
+		local.Name: local.NewConfig(),
+	}
+
+	backend, ok := backends[lokoConfig.RootConfig.Backend.Name]
+	if !ok {
 		diag := &hcl.Diagnostic{
 			Severity: hcl.DiagError,
-			Summary:  err.Error(),
+			Summary:  fmt.Sprintf("no backend with name %q found", lokoConfig.RootConfig.Backend.Name),
 		}
 		return nil, hcl.Diagnostics{diag}
 	}
 
 	return backend, backend.LoadConfig(&lokoConfig.RootConfig.Backend.Config, lokoConfig.EvalContext)
 }
 
+func getPlatform(name string) (platform.Platform, error) {
+	platforms := map[string]platform.Platform{
+		aks.Name:        aks.NewConfig(),
+		aws.Name:        aws.NewConfig(),
+		packet.Name:     packet.NewConfig(),
+		baremetal.Name:  baremetal.NewConfig(),
+		tinkerbell.Name: tinkerbell.NewConfig(),
+	}
+
+	if p, ok := platforms[name]; ok {
+		return p, nil
+	}
+
+	return nil, fmt.Errorf("platform %q not found", name)
+}
+
 // getConfiguredPlatform loads a platform from the given configuration file.
 func getConfiguredPlatform(lokoConfig *config.Config, require bool) (platform.Platform, hcl.Diagnostics) {
 	if lokoConfig.RootConfig.Cluster == nil && !require {
@@ -70,7 +107,7 @@ func getConfiguredPlatform(lokoConfig *config.Config, require bool) (platform.Pl
 		}
 	}
 
-	platform, err := platform.GetPlatform(lokoConfig.RootConfig.Cluster.Name)
+	platform, err := getPlatform(lokoConfig.RootConfig.Cluster.Name)
 	if err != nil {
 		diag := &hcl.Diagnostic{
 			Severity: hcl.DiagError,

pkg/backend/backend.go

@@ -15,8 +15,6 @@
 package backend
 
 import (
-	"fmt"
-
 	"github.com/hashicorp/hcl/v2"
 )
 
@@ -29,28 +27,3 @@ type Backend interface {
 	// Validate validates backend configuration.
 	Validate() error
 }
-
-// backends is a collection in which all Backends get automatically registered.
-var backends map[string]Backend
-
-// Initialize package's global variable on import.
-func init() {
-	backends = make(map[string]Backend)
-}
-
-// Register registers Backend b in the internal backends map.
-func Register(name string, b Backend) {
-	if _, exists := backends[name]; exists {
-		panic(fmt.Sprintf("backend with name %q registered already", name))
-	}
-	backends[name] = b
-}
-
-// GetBackend returns the Backend referred to by name.
-func GetBackend(name string) (Backend, error) {
-	backend, exists := backends[name]
-	if !exists {
-		return nil, fmt.Errorf("no backend with name %q found", name)
-	}
-	return backend, nil
-}

pkg/backend/local/local.go

@@ -19,17 +19,17 @@ import (
 	"github.com/hashicorp/hcl/v2/gohcl"
 
 	"github.com/kinvolk/lokomotive/internal/template"
-	"github.com/kinvolk/lokomotive/pkg/backend"
 )
 
 type local struct {
 	Path string `hcl:"path,optional"`
 }
 
-// init registers local as a backend.
-func init() {
-	backend.Register("local", NewLocalBackend())
-}
+const (
+	// Name represents Local backend name as it should be referenced in function calls
+	// and in configuration.
+	Name = "local"
+)
 
 // LoadConfig loads the configuration for the local backend.
 func (l *local) LoadConfig(configBody *hcl.Body, evalContext *hcl.EvalContext) hcl.Diagnostics {
@@ -39,7 +39,10 @@ func (l *local) LoadConfig(configBody *hcl.Body, evalContext *hcl.EvalContext) h
 	return gohcl.DecodeBody(*configBody, evalContext, l)
 }
 
-func NewLocalBackend() *local {
+// NewConfig returns new Local backend configuration with default values set.
+//
+//nolint:golint
+func NewConfig() *local {
 	return &local{}
 }
 

pkg/backend/s3/s3.go

@@ -22,7 +22,6 @@ import (
 	"github.com/hashicorp/hcl/v2/gohcl"
 
 	"github.com/kinvolk/lokomotive/internal/template"
-	"github.com/kinvolk/lokomotive/pkg/backend"
 )
 
 type s3 struct {
@@ -33,10 +32,11 @@ type s3 struct {
 	DynamoDBTable string `hcl:"dynamodb_table,optional"`
 }
 
-// init registers s3 as a backend.
-func init() {
-	backend.Register("s3", NewS3Backend())
-}
+const (
+	// Name represents S3 backend name as it should be referenced in function calls
+	// and in configuration.
+	Name = "s3"
+)
 
 // LoadConfig loads the configuration for the s3 backend.
 func (s *s3) LoadConfig(configBody *hcl.Body, evalContext *hcl.EvalContext) hcl.Diagnostics {
@@ -46,7 +46,10 @@ func (s *s3) LoadConfig(configBody *hcl.Body, evalContext *hcl.EvalContext) hcl.
 	return gohcl.DecodeBody(*configBody, evalContext, s)
 }
 
-func NewS3Backend() *s3 {
+// NewConfig returns new Local backend configuration with default values set.
+//
+//nolint:golint
+func NewConfig() *s3 {
 	return &s3{}
 }