certificate: add new package for CSR resource (#810)

* Adds the CertificateSigningRequest resource and creates a new
  certificate package for it.
* Adds listing functions, along with a method to wait until all CSRs are
  approved.
* Unit tests are provided for all exported functions.

pkg/certificate/signingrequest.go

@@ -0,0 +1,176 @@
+package certificate
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/golang/glog"
+	"github.com/openshift-kni/eco-goinfra/pkg/clients"
+	"github.com/openshift-kni/eco-goinfra/pkg/msg"
+	certificatesv1 "k8s.io/api/certificates/v1"
+	k8serrors "k8s.io/apimachinery/pkg/api/errors"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	runtimeclient "sigs.k8s.io/controller-runtime/pkg/client"
+)
+
+// SigningRequestBuilder provides a struct for CertificateSigningRequest resource containing a connection to the cluster
+// and the CertificateSigningRequest definition.
+type SigningRequestBuilder struct {
+	// SigningRequest definition, used to create the signing request object.
+	Definition *certificatesv1.CertificateSigningRequest
+	// Created signing request object on cluster.
+	Object *certificatesv1.CertificateSigningRequest
+	// apiClient to interact with the cluster.
+	apiClient runtimeclient.Client
+}
+
+// PullSigningRequest loads an existing signing request into SigningRequestBuilder struct.
+func PullSigningRequest(apiClient *clients.Settings, name string) (*SigningRequestBuilder, error) {
+	glog.V(100).Infof("Pulling existing CertificateSigningRequest with name %s", name)
+
+	if apiClient == nil {
+		glog.V(100).Infof("CertificateSigningRequest apiClient cannot be nil")
+
+		return nil, fmt.Errorf("certificateSigniingRequest apiClient cannot be nil")
+	}
+
+	err := apiClient.AttachScheme(certificatesv1.AddToScheme)
+	if err != nil {
+		glog.V(100).Infof("Failed to add certificates v1 scheme to client schemes")
+
+		return nil, err
+	}
+
+	builder := &SigningRequestBuilder{
+		apiClient: apiClient.Client,
+		Definition: &certificatesv1.CertificateSigningRequest{
+			ObjectMeta: metav1.ObjectMeta{
+				Name: name,
+			},
+		},
+	}
+
+	if name == "" {
+		glog.V(100).Infof("The name of the CertificateSigningRequest is empty")
+
+		return nil, fmt.Errorf("certificateSigningRequest 'name' cannot be empty")
+	}
+
+	if !builder.Exists() {
+		glog.V(100).Infof("CertificateSigningRequest %s does not exist", name)
+
+		return nil, fmt.Errorf("certificateSigningRequest %s does not exist", name)
+	}
+
+	builder.Definition = builder.Object
+
+	return builder, nil
+}
+
+// Get returns the CertificateSigningRequest object if found.
+func (builder *SigningRequestBuilder) Get() (*certificatesv1.CertificateSigningRequest, error) {
+	if valid, err := builder.validate(); !valid {
+		return nil, err
+	}
+
+	glog.V(100).Infof("Collecting CertificateSigningRequest object %s", builder.Definition.Name)
+
+	signingRequest := &certificatesv1.CertificateSigningRequest{}
+	err := builder.apiClient.Get(context.TODO(), runtimeclient.ObjectKey{
+		Name: builder.Definition.Name,
+	}, signingRequest)
+
+	if err != nil {
+		glog.V(100).Infof("Failed to get CertificateSigningRequest object %s: %v", builder.Definition.Name, err)
+
+		return nil, err
+	}
+
+	return signingRequest, nil
+}
+
+// Exists checks whether the given CertificateSigningRequest object exists.
+func (builder *SigningRequestBuilder) Exists() bool {
+	if valid, _ := builder.validate(); !valid {
+		return false
+	}
+
+	glog.V(100).Infof("Checking if CertificateSigningRequest %s exists", builder.Definition.Name)
+
+	var err error
+	builder.Object, err = builder.Get()
+
+	return err == nil || !k8serrors.IsNotFound(err)
+}
+
+// Create creates a new CertificateSigningRequest object if it does not exist.
+func (builder *SigningRequestBuilder) Create() (*SigningRequestBuilder, error) {
+	if valid, err := builder.validate(); !valid {
+		return builder, err
+	}
+
+	glog.V(100).Infof("Creating CertificateSigningRequest %s", builder.Definition.Name)
+
+	if builder.Exists() {
+		return builder, nil
+	}
+
+	err := builder.apiClient.Create(context.TODO(), builder.Definition)
+	if err != nil {
+		return builder, err
+	}
+
+	builder.Object = builder.Definition
+
+	return builder, nil
+}
+
+// Delete removes a CertificateSigningRequest object from the cluster if it exists.
+func (builder *SigningRequestBuilder) Delete() error {
+	if valid, err := builder.validate(); !valid {
+		return err
+	}
+
+	glog.V(100).Infof("Deleting CertificateSigningRequest %s", builder.Definition.Name)
+
+	if !builder.Exists() {
+		glog.V(100).Infof("CertificateSigningRequest %s does not exist", builder.Definition.Name)
+
+		builder.Object = nil
+
+		return nil
+	}
+
+	err := builder.apiClient.Delete(context.TODO(), builder.Definition)
+	if err != nil {
+		return err
+	}
+
+	builder.Object = nil
+
+	return nil
+}
+
+func (builder *SigningRequestBuilder) validate() (bool, error) {
+	resourceCRD := "certificateSigningRequest"
+
+	if builder == nil {
+		glog.V(100).Infof("The %s builder is uninitialized", resourceCRD)
+
+		return false, fmt.Errorf("error: received nil %s builder", resourceCRD)
+	}
+
+	if builder.Definition == nil {
+		glog.V(100).Infof("The %s is undefined", resourceCRD)
+
+		return false, fmt.Errorf(msg.UndefinedCrdObjectErrString(resourceCRD))
+	}
+
+	if builder.apiClient == nil {
+		glog.V(100).Infof("The %s builder apiclient is nil", resourceCRD)
+
+		return false, fmt.Errorf("%s builder cannot have nil apiClient", resourceCRD)
+	}
+
+	return true, nil
+}