Add HashiCorp Nomad provider (#483)

* provider: adding Nomad provider

* updating CONTRIBUTING.md with Nomad provider

* updated README.md by adding the Nomad provider

* fix typo

* adding nomad/api and nomad/testutil deps

* adding Nomad binary dependency for provider tests

* fixed the nomad binary download command step and added tolerations to the nomad provider.

* adding nomad provider demo gif

* adding my name to authors

* adding two missing go-rootcerts files after dep ensure

* delete pod comment

providers/nomad/nomad_test.go

@@ -0,0 +1,125 @@
+package nomad
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"testing"
+
+	"github.com/google/uuid"
+	nomad "github.com/hashicorp/nomad/api"
+	"github.com/hashicorp/nomad/testutil"
+	"github.com/stretchr/testify/assert"
+	v1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/util/intstr"
+)
+
+// Client provides a client to the Nomad API
+type Client struct {
+	config nomad.Config
+}
+
+func TestCreateGetDeletePod(t *testing.T) {
+	provider, err := makeProvider(t)
+	if err != nil {
+		t.Fatal("unable to create mock provider", err)
+	}
+
+	nomadClient, nomadServer := makeClient(t, nil)
+	defer nomadServer.Stop()
+
+	provider.nomadClient = nomadClient
+	provider.nomadAddress = nomadServer.HTTPAddr
+
+	podName := "pod-" + uuid.New().String()
+	podNamespace := "ns-" + uuid.New().String()
+
+	pod := &v1.Pod{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:      podName,
+			Namespace: podNamespace,
+		},
+		Spec: v1.PodSpec{
+			Containers: []v1.Container{
+				v1.Container{
+					Name:  "nginx",
+					Image: "nginx",
+					LivenessProbe: &v1.Probe{
+						Handler: v1.Handler{
+							HTTPGet: &v1.HTTPGetAction{
+								Port: intstr.FromString("8080"),
+								Path: "/",
+							},
+						},
+						InitialDelaySeconds: 10,
+						PeriodSeconds:       5,
+						TimeoutSeconds:      60,
+						SuccessThreshold:    3,
+						FailureThreshold:    5,
+					},
+				},
+			},
+		},
+	}
+
+	// Create pod
+	err = provider.CreatePod(context.Background(), pod)
+	if err != nil {
+		t.Fatal("failed to create pod", err)
+	}
+
+	// Get pod
+	pod, err = provider.GetPod(context.Background(), podNamespace, podName)
+	if err != nil {
+		t.Fatal("failed to get pod", err)
+	}
+
+	// Get pod tests
+	// Validate pod spec
+	assert.NotNil(t, pod, "pod cannot be nil")
+	assert.NotNil(t, pod.Spec.Containers, "containers cannot be nil")
+	assert.Nil(t, pod.Annotations, "pod annotations should be nil")
+	assert.Equal(t, pod.Name, fmt.Sprintf("%s-%s", jobNamePrefix, podName), "pod name should be equal")
+
+	// Get pods
+	pods, err := provider.GetPods(context.Background())
+	if err != nil {
+		t.Fatal("failed to get pods", err)
+	}
+
+	// TODO: finish adding a few more assertions
+	assert.Len(t, pods, 1, "number of pods should be 1")
+
+	// Delete pod
+	err = provider.DeletePod(context.Background(), pod)
+	if err != nil {
+		t.Fatal("failed to delete pod", err)
+	}
+}
+
+func makeClient(t *testing.T, cb testutil.ServerConfigCallback) (*nomad.Client, *testutil.TestServer) {
+	// Make client config
+	conf := nomad.DefaultConfig()
+	// Create server
+	server := testutil.NewTestServer(t, cb)
+	conf.Address = "http://" + server.HTTPAddr
+	// Create client
+	client, err := nomad.NewClient(conf)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	return client, server
+}
+
+func makeProvider(t *testing.T) (*Provider, error) {
+	// Set default region
+	os.Setenv("NOMAD_REGION", "global")
+
+	provider, err := NewProvider(nil, "fakeNomadNode", "linux")
+	if err != nil {
+		return nil, err
+	}
+
+	return provider, nil
+}