kubectl-persistent-logger/logs/pod_watcher_test.go

package logs_test

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"io"
	"net/http"
	"strings"
	"testing"
	"time"

	"git.netflux.io/rob/kubectl-persistent-logger/logs"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	corev1 "k8s.io/api/core/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/watch"
	testclient "k8s.io/client-go/kubernetes/fake"
	"k8s.io/client-go/kubernetes/scheme"
	clientv1 "k8s.io/client-go/kubernetes/typed/core/v1"
	"k8s.io/client-go/rest"
	fakerest "k8s.io/client-go/rest/fake"
	k8stest "k8s.io/client-go/testing"
)

type mockClientset struct {
	testclient.Clientset
	clientv1.CoreV1Interface
	clientv1.PodInterface

	podsWatcher       watch.Interface
	getLogsStatusCode int
	getLogsRespBody   string
	getLogsErr        error
}

func (m *mockClientset) CoreV1() clientv1.CoreV1Interface  { return m }
func (m *mockClientset) Pods(string) clientv1.PodInterface { return m }
func (m *mockClientset) Watch(context.Context, metav1.ListOptions) (watch.Interface, error) {
	return m.podsWatcher, nil
}

func (m *mockClientset) GetLogs(podName string, _ *corev1.PodLogOptions) *rest.Request {
	fakeClient := fakerest.RESTClient{
		Client: fakerest.CreateHTTPClient(func(*http.Request) (*http.Response, error) {
			if m.getLogsErr != nil {
				return nil, m.getLogsErr
			}
			return &http.Response{
				StatusCode: m.getLogsStatusCode,
				Body:       io.NopCloser(strings.NewReader(m.getLogsRespBody)),
			}, nil
		}),
		NegotiatedSerializer: scheme.Codecs.WithoutConversion(),
		VersionedAPIPath:     fmt.Sprintf("/api/v1/namespaces/default/pods/%s/log", podName),
	}
	return fakeClient.Request()
}

func TestPodWatcher(t *testing.T) {
	testCases := []struct {
		name              string
		getLogsRespBody   string
		getLogsStatusCode int
		getLogsErr        error
		wantOut           []string
		wantErr           string
	}{
		{
			name:       "unexpected error getting logs",
			getLogsErr: errors.New("nope"),
			wantOut:    nil,
			wantErr:    "nope",
		},
		{
			name:       "recoverable error getting logs",
			getLogsErr: &apierrors.StatusError{ErrStatus: metav1.Status{Message: "is waiting to start: ContainerCreating", Reason: metav1.StatusReasonBadRequest}},
			wantOut:    nil,
			wantErr:    context.DeadlineExceeded.Error(),
		},
		{
			name:              "success",
			getLogsRespBody:   "some logs",
			getLogsStatusCode: http.StatusOK,
			wantOut:           []string{"[foo] some logs", "[bar] some logs"},
			wantErr:           context.DeadlineExceeded.Error(),
		},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
			defer cancel()

			podsWatcher := watch.NewFake()
			defer podsWatcher.Stop()

			clientset := mockClientset{
				getLogsRespBody:   tc.getLogsRespBody,
				getLogsStatusCode: tc.getLogsStatusCode,
				getLogsErr:        tc.getLogsErr,
				podsWatcher:       podsWatcher,
			}
			clientset.PrependWatchReactor("pods", k8stest.DefaultWatchReactor(podsWatcher, nil))

			client := logs.KubernetesClient{Interface: &clientset}
			selector := metav1.LabelSelector{MatchLabels: map[string]string{"foo": "bar"}}

			go func() {
				pods := []*corev1.Pod{
					{
						ObjectMeta: metav1.ObjectMeta{Name: "foo", Namespace: "default"},
						Status:     corev1.PodStatus{Phase: corev1.PodRunning},
					},
					{
						ObjectMeta: metav1.ObjectMeta{Name: "bar", Namespace: "default"},
						Status:     corev1.PodStatus{Phase: corev1.PodRunning},
					},
					{
						ObjectMeta: metav1.ObjectMeta{Name: "baz", Namespace: "default"},
						Status:     corev1.PodStatus{Phase: corev1.PodPending},
					},
				}
				for _, pod := range pods {
					podsWatcher.Add(pod)
					time.Sleep(time.Millisecond * 250)
				}
			}()

			var buf bytes.Buffer
			pw := logs.NewPodWatcher(client, "mycontainer", &selector, &buf)

			err := pw.WatchPods(ctx)

			if tc.wantErr == "" {
				require.NoError(t, err)
			} else {
				require.Contains(t, err.Error(), tc.wantErr)
			}
			if tc.wantOut != nil {
				assert.ElementsMatch(t, tc.wantOut, splitBuf(&buf))
			}
		})
	}
}