VictoriaMetrics/lib/promscrape/discovery/kubernetes/api_watcher.go
Aliaksandr Valialkin fe084fdd33 lib/promscrape/discovery/kubernetes: synchronously load Kubernetes objects on first access
Remove async registration of apiWatchers, since it breaks discovering `role: endpoints` and `role: endpointslices` targets,
which depend on pod and service objects.

There is no need in reloading `endpoints` and `endpointslices` targets if the referenced `pod` or `service` objects change,
since in this case the corresponding `endpoints` and `endpointslices` objects should also change because they contain
ResourceVersion of the referenced `pod` or `service` objects, which is modified on object update.

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1182
2021-04-05 14:37:07 +03:00

720 lines
20 KiB
Go

package kubernetes
import (
"encoding/json"
"errors"
"flag"
"fmt"
"io"
"io/ioutil"
"net/http"
"net/url"
"reflect"
"strconv"
"strings"
"sync"
"time"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/promauth"
"github.com/VictoriaMetrics/metrics"
)
var apiServerTimeout = flag.Duration("promscrape.kubernetes.apiServerTimeout", 30*time.Minute, "How frequently to reload the full state from Kuberntes API server")
// WatchEvent is a watch event returned from API server endpoints if `watch=1` query arg is set.
//
// See https://kubernetes.io/docs/reference/using-api/api-concepts/#efficient-detection-of-changes
type WatchEvent struct {
Type string
Object json.RawMessage
}
// object is any Kubernetes object.
type object interface {
key() string
getTargetLabels(gw *groupWatcher) []map[string]string
}
// parseObjectFunc must parse object from the given data.
type parseObjectFunc func(data []byte) (object, error)
// parseObjectListFunc must parse objectList from the given r.
type parseObjectListFunc func(r io.Reader) (map[string]object, ListMeta, error)
// apiWatcher is used for watching for Kuberntes object changes and caching their latest states.
type apiWatcher struct {
role string
// Constructor for creating ScrapeWork objects from labels
swcFunc ScrapeWorkConstructorFunc
gw *groupWatcher
// swos contains per-namepsace maps of ScrapeWork objects for the given apiWatcher
swosByNamespace map[string]map[string][]interface{}
swosByNamespaceLock sync.Mutex
swosCount *metrics.Counter
}
func newAPIWatcher(apiServer string, ac *promauth.Config, sdc *SDConfig, swcFunc ScrapeWorkConstructorFunc) *apiWatcher {
namespaces := sdc.Namespaces.Names
selectors := sdc.Selectors
proxyURL := sdc.ProxyURL.URL()
gw := getGroupWatcher(apiServer, ac, namespaces, selectors, proxyURL)
return &apiWatcher{
role: sdc.Role,
swcFunc: swcFunc,
gw: gw,
swosByNamespace: make(map[string]map[string][]interface{}),
swosCount: metrics.GetOrCreateCounter(fmt.Sprintf(`vm_promscrape_discovery_kubernetes_scrape_works{role=%q}`, sdc.Role)),
}
}
func (aw *apiWatcher) mustStop() {
aw.gw.unsubscribeAPIWatcher(aw)
aw.swosByNamespaceLock.Lock()
aw.swosByNamespace = make(map[string]map[string][]interface{})
aw.swosByNamespaceLock.Unlock()
}
func (aw *apiWatcher) reloadScrapeWorks(namespace string, swosByKey map[string][]interface{}) {
aw.swosByNamespaceLock.Lock()
aw.swosCount.Add(len(swosByKey) - len(aw.swosByNamespace[namespace]))
aw.swosByNamespace[namespace] = swosByKey
aw.swosByNamespaceLock.Unlock()
}
func (aw *apiWatcher) setScrapeWorks(namespace, key string, labels []map[string]string) {
swos := aw.getScrapeWorkObjectsForLabels(labels)
aw.swosByNamespaceLock.Lock()
swosByKey := aw.swosByNamespace[namespace]
if swosByKey == nil {
swosByKey = make(map[string][]interface{})
aw.swosByNamespace[namespace] = swosByKey
}
if len(swos) > 0 {
aw.swosCount.Add(len(swos) - len(swosByKey[key]))
swosByKey[key] = swos
} else {
aw.swosCount.Add(-len(swosByKey[key]))
delete(swosByKey, key)
}
aw.swosByNamespaceLock.Unlock()
}
func (aw *apiWatcher) removeScrapeWorks(namespace, key string) {
aw.swosByNamespaceLock.Lock()
swosByKey := aw.swosByNamespace[namespace]
if len(swosByKey) > 0 {
aw.swosCount.Add(-len(swosByKey[key]))
delete(swosByKey, key)
}
aw.swosByNamespaceLock.Unlock()
}
func (aw *apiWatcher) getScrapeWorkObjectsForLabels(labelss []map[string]string) []interface{} {
swos := make([]interface{}, 0, len(labelss))
for _, labels := range labelss {
swo := aw.swcFunc(labels)
// The reflect check is needed because of https://mangatmodi.medium.com/go-check-nil-interface-the-right-way-d142776edef1
if swo != nil && !reflect.ValueOf(swo).IsNil() {
swos = append(swos, swo)
}
}
return swos
}
// getScrapeWorkObjects returns all the ScrapeWork objects for the given aw.
func (aw *apiWatcher) getScrapeWorkObjects() []interface{} {
aw.gw.startWatchersForRole(aw.role, aw)
aw.swosByNamespaceLock.Lock()
defer aw.swosByNamespaceLock.Unlock()
size := 0
for _, swosByKey := range aw.swosByNamespace {
for _, swosLocal := range swosByKey {
size += len(swosLocal)
}
}
swos := make([]interface{}, 0, size)
for _, swosByKey := range aw.swosByNamespace {
for _, swosLocal := range swosByKey {
swos = append(swos, swosLocal...)
}
}
return swos
}
// groupWatcher watches for Kubernetes objects on the given apiServer with the given namespaces,
// selectors and authorization using the given client.
type groupWatcher struct {
apiServer string
namespaces []string
selectors []Selector
authorization string
client *http.Client
mu sync.Mutex
m map[string]*urlWatcher
}
func newGroupWatcher(apiServer string, ac *promauth.Config, namespaces []string, selectors []Selector, proxyURL *url.URL) *groupWatcher {
var proxy func(*http.Request) (*url.URL, error)
if proxyURL != nil {
proxy = http.ProxyURL(proxyURL)
}
client := &http.Client{
Transport: &http.Transport{
TLSClientConfig: ac.NewTLSConfig(),
Proxy: proxy,
TLSHandshakeTimeout: 10 * time.Second,
IdleConnTimeout: *apiServerTimeout,
},
Timeout: *apiServerTimeout,
}
return &groupWatcher{
apiServer: apiServer,
authorization: ac.Authorization,
namespaces: namespaces,
selectors: selectors,
client: client,
m: make(map[string]*urlWatcher),
}
}
func getGroupWatcher(apiServer string, ac *promauth.Config, namespaces []string, selectors []Selector, proxyURL *url.URL) *groupWatcher {
key := fmt.Sprintf("apiServer=%s, namespaces=%s, selectors=%s, proxyURL=%v, authConfig=%s",
apiServer, namespaces, selectorsKey(selectors), proxyURL, ac.String())
groupWatchersLock.Lock()
gw := groupWatchers[key]
if gw == nil {
gw = newGroupWatcher(apiServer, ac, namespaces, selectors, proxyURL)
groupWatchers[key] = gw
}
groupWatchersLock.Unlock()
return gw
}
func selectorsKey(selectors []Selector) string {
var sb strings.Builder
for _, s := range selectors {
fmt.Fprintf(&sb, "{role=%q, label=%q, field=%q}", s.Role, s.Label, s.Field)
}
return sb.String()
}
var (
groupWatchersLock sync.Mutex
groupWatchers = make(map[string]*groupWatcher)
_ = metrics.NewGauge(`vm_promscrape_discovery_kubernetes_group_watchers`, func() float64 {
groupWatchersLock.Lock()
n := len(groupWatchers)
groupWatchersLock.Unlock()
return float64(n)
})
)
// getObjectByRole returns an object with the given (namespace, name) key and the given role.
func (gw *groupWatcher) getObjectByRole(role, namespace, name string) object {
if gw == nil {
// this is needed for testing
return nil
}
key := namespace + "/" + name
gw.startWatchersForRole(role, nil)
gw.mu.Lock()
defer gw.mu.Unlock()
for _, uw := range gw.m {
if uw.role != role {
// Role mismatch
continue
}
if uw.namespace != "" && uw.namespace != namespace {
// Namespace mismatch
continue
}
uw.mu.Lock()
o := uw.objectsByKey[key]
uw.mu.Unlock()
if o != nil {
return o
}
}
return nil
}
func (gw *groupWatcher) startWatchersForRole(role string, aw *apiWatcher) {
paths, namespaces := getAPIPathsWithNamespaces(role, gw.namespaces, gw.selectors)
for i, path := range paths {
apiURL := gw.apiServer + path
gw.mu.Lock()
uw := gw.m[apiURL]
needStart := uw == nil
if needStart {
uw = newURLWatcher(role, namespaces[i], apiURL, gw)
gw.m[apiURL] = uw
}
gw.mu.Unlock()
if needStart {
uw.reloadObjects()
go uw.watchForUpdates()
}
uw.subscribeAPIWatcher(aw)
}
}
// doRequest performs http request to the given requestURL.
func (gw *groupWatcher) doRequest(requestURL string) (*http.Response, error) {
req, err := http.NewRequest("GET", requestURL, nil)
if err != nil {
logger.Fatalf("cannot create a request for %q: %s", requestURL, err)
}
if gw.authorization != "" {
req.Header.Set("Authorization", gw.authorization)
}
return gw.client.Do(req)
}
func (gw *groupWatcher) unsubscribeAPIWatcher(aw *apiWatcher) {
gw.mu.Lock()
for _, uw := range gw.m {
uw.unsubscribeAPIWatcher(aw)
}
gw.mu.Unlock()
}
// urlWatcher watches for an apiURL and updates object states in objectsByKey.
type urlWatcher struct {
role string
namespace string
apiURL string
gw *groupWatcher
parseObject parseObjectFunc
parseObjectList parseObjectListFunc
// mu protects aws, objectsByKey and resourceVersion
mu sync.Mutex
// aws contains registered apiWatcher objects
aws map[*apiWatcher]struct{}
// objectsByKey contains the latest state for objects obtained from apiURL
objectsByKey map[string]object
resourceVersion string
objectsCount *metrics.Counter
objectsAdded *metrics.Counter
objectsRemoved *metrics.Counter
objectsUpdated *metrics.Counter
staleResourceVersions *metrics.Counter
}
func newURLWatcher(role, namespace, apiURL string, gw *groupWatcher) *urlWatcher {
parseObject, parseObjectList := getObjectParsersForRole(role)
metrics.GetOrCreateCounter(fmt.Sprintf(`vm_promscrape_discovery_kubernetes_url_watchers{role=%q}`, role)).Inc()
uw := &urlWatcher{
role: role,
namespace: namespace,
apiURL: apiURL,
gw: gw,
parseObject: parseObject,
parseObjectList: parseObjectList,
aws: make(map[*apiWatcher]struct{}),
objectsByKey: make(map[string]object),
objectsCount: metrics.GetOrCreateCounter(fmt.Sprintf(`vm_promscrape_discovery_kubernetes_objects{role=%q}`, role)),
objectsAdded: metrics.GetOrCreateCounter(fmt.Sprintf(`vm_promscrape_discovery_kubernetes_objects_added_total{role=%q}`, role)),
objectsRemoved: metrics.GetOrCreateCounter(fmt.Sprintf(`vm_promscrape_discovery_kubernetes_objects_removed_total{role=%q}`, role)),
objectsUpdated: metrics.GetOrCreateCounter(fmt.Sprintf(`vm_promscrape_discovery_kubernetes_objects_updated_total{role=%q}`, role)),
staleResourceVersions: metrics.GetOrCreateCounter(fmt.Sprintf(`vm_promscrape_discovery_kubernetes_stale_resource_versions_total{role=%q}`, role)),
}
logger.Infof("started %s watcher for %q", uw.role, uw.apiURL)
return uw
}
func (uw *urlWatcher) subscribeAPIWatcher(aw *apiWatcher) {
if aw == nil {
return
}
uw.mu.Lock()
if _, ok := uw.aws[aw]; !ok {
swosByKey := make(map[string][]interface{})
for key, o := range uw.objectsByKey {
labels := o.getTargetLabels(uw.gw)
swos := aw.getScrapeWorkObjectsForLabels(labels)
if len(swos) > 0 {
swosByKey[key] = swos
}
}
aw.reloadScrapeWorks(uw.namespace, swosByKey)
metrics.GetOrCreateCounter(fmt.Sprintf(`vm_promscrape_discovery_kubernetes_subscibers{role=%q}`, uw.role)).Inc()
}
uw.mu.Unlock()
}
func (uw *urlWatcher) unsubscribeAPIWatcher(aw *apiWatcher) {
uw.mu.Lock()
if _, ok := uw.aws[aw]; ok {
delete(uw.aws, aw)
metrics.GetOrCreateCounter(fmt.Sprintf(`vm_promscrape_discovery_kubernetes_subscibers{role=%q}`, uw.role)).Dec()
}
uw.mu.Unlock()
}
func (uw *urlWatcher) setResourceVersion(resourceVersion string) {
uw.mu.Lock()
uw.resourceVersion = resourceVersion
uw.mu.Unlock()
}
// reloadObjects reloads objects to the latest state and returns resourceVersion for the latest state.
func (uw *urlWatcher) reloadObjects() string {
uw.mu.Lock()
resourceVersion := uw.resourceVersion
uw.mu.Unlock()
if resourceVersion != "" {
// Fast path - there is no need in reloading the objects.
return resourceVersion
}
requestURL := uw.apiURL
resp, err := uw.gw.doRequest(requestURL)
if err != nil {
logger.Errorf("cannot perform request to %q: %s", requestURL, err)
return ""
}
if resp.StatusCode != http.StatusOK {
body, _ := ioutil.ReadAll(resp.Body)
_ = resp.Body.Close()
logger.Errorf("unexpected status code for request to %q: %d; want %d; response: %q", requestURL, resp.StatusCode, http.StatusOK, body)
return ""
}
objectsByKey, metadata, err := uw.parseObjectList(resp.Body)
_ = resp.Body.Close()
if err != nil {
logger.Errorf("cannot parse objects from %q: %s", requestURL, err)
return ""
}
uw.mu.Lock()
var updated, removed, added int
for key := range uw.objectsByKey {
if o, ok := objectsByKey[key]; ok {
uw.objectsByKey[key] = o
updated++
} else {
delete(uw.objectsByKey, key)
removed++
}
}
for key, o := range objectsByKey {
if _, ok := uw.objectsByKey[key]; !ok {
uw.objectsByKey[key] = o
added++
}
}
uw.objectsUpdated.Add(updated)
uw.objectsRemoved.Add(removed)
uw.objectsAdded.Add(added)
uw.objectsCount.Add(added - removed)
uw.resourceVersion = metadata.ResourceVersion
aws := getAPIWatchers(uw.aws)
uw.mu.Unlock()
uw.reloadScrapeWorksForAPIWatchers(aws, objectsByKey)
logger.Infof("reloaded %d objects from %q", len(objectsByKey), requestURL)
return uw.resourceVersion
}
func (uw *urlWatcher) reloadScrapeWorksForAPIWatchers(aws []*apiWatcher, objectsByKey map[string]object) {
if len(aws) == 0 {
return
}
swosByKey := make([]map[string][]interface{}, len(aws))
for i := range aws {
swosByKey[i] = make(map[string][]interface{})
}
for key, o := range objectsByKey {
labels := o.getTargetLabels(uw.gw)
for i, aw := range aws {
swos := aw.getScrapeWorkObjectsForLabels(labels)
if len(swos) > 0 {
swosByKey[i][key] = swos
}
}
}
for i, aw := range aws {
aw.reloadScrapeWorks(uw.namespace, swosByKey[i])
}
}
func getAPIWatchers(awsMap map[*apiWatcher]struct{}) []*apiWatcher {
aws := make([]*apiWatcher, 0, len(awsMap))
for aw := range awsMap {
aws = append(aws, aw)
}
return aws
}
// watchForUpdates watches for object updates starting from uw.resourceVersion and updates the corresponding objects to the latest state.
//
// See https://kubernetes.io/docs/reference/using-api/api-concepts/#efficient-detection-of-changes
func (uw *urlWatcher) watchForUpdates() {
backoffDelay := time.Second
maxBackoffDelay := 30 * time.Second
backoffSleep := func() {
time.Sleep(backoffDelay)
backoffDelay *= 2
if backoffDelay > maxBackoffDelay {
backoffDelay = maxBackoffDelay
}
}
apiURL := uw.apiURL
delimiter := "?"
if strings.Contains(apiURL, "?") {
delimiter = "&"
}
timeoutSeconds := time.Duration(0.9 * float64(uw.gw.client.Timeout)).Seconds()
apiURL += delimiter + "watch=1&allowWatchBookmarks=true&timeoutSeconds=" + strconv.Itoa(int(timeoutSeconds))
for {
resourceVersion := uw.reloadObjects()
if resourceVersion == "" {
backoffSleep()
continue
}
requestURL := apiURL + "&resourceVersion=" + url.QueryEscape(resourceVersion)
resp, err := uw.gw.doRequest(requestURL)
if err != nil {
logger.Errorf("cannot perform request to %q: %s", requestURL, err)
backoffSleep()
continue
}
if resp.StatusCode != http.StatusOK {
if resp.StatusCode == 410 {
// There is no need for sleep on 410 error. See https://kubernetes.io/docs/reference/using-api/api-concepts/#410-gone-responses
backoffDelay = time.Second
uw.staleResourceVersions.Inc()
uw.setResourceVersion("")
} else {
body, _ := ioutil.ReadAll(resp.Body)
_ = resp.Body.Close()
logger.Errorf("unexpected status code for request to %q: %d; want %d; response: %q", requestURL, resp.StatusCode, http.StatusOK, body)
backoffSleep()
}
continue
}
backoffDelay = time.Second
err = uw.readObjectUpdateStream(resp.Body)
_ = resp.Body.Close()
if err != nil {
if !errors.Is(err, io.EOF) {
logger.Errorf("error when reading WatchEvent stream from %q: %s", requestURL, err)
}
backoffSleep()
continue
}
}
}
// readObjectUpdateStream reads Kuberntes watch events from r and updates locally cached objects according to the received events.
func (uw *urlWatcher) readObjectUpdateStream(r io.Reader) error {
d := json.NewDecoder(r)
var we WatchEvent
for {
if err := d.Decode(&we); err != nil {
return err
}
switch we.Type {
case "ADDED", "MODIFIED":
o, err := uw.parseObject(we.Object)
if err != nil {
return err
}
key := o.key()
uw.mu.Lock()
if _, ok := uw.objectsByKey[key]; !ok {
uw.objectsCount.Inc()
uw.objectsAdded.Inc()
} else {
uw.objectsUpdated.Inc()
}
uw.objectsByKey[key] = o
aws := getAPIWatchers(uw.aws)
uw.mu.Unlock()
labels := o.getTargetLabels(uw.gw)
for _, aw := range aws {
aw.setScrapeWorks(uw.namespace, key, labels)
}
case "DELETED":
o, err := uw.parseObject(we.Object)
if err != nil {
return err
}
key := o.key()
uw.mu.Lock()
if _, ok := uw.objectsByKey[key]; ok {
uw.objectsCount.Dec()
uw.objectsRemoved.Inc()
delete(uw.objectsByKey, key)
}
aws := getAPIWatchers(uw.aws)
uw.mu.Unlock()
for _, aw := range aws {
aw.removeScrapeWorks(uw.namespace, key)
}
case "BOOKMARK":
// See https://kubernetes.io/docs/reference/using-api/api-concepts/#watch-bookmarks
bm, err := parseBookmark(we.Object)
if err != nil {
return fmt.Errorf("cannot parse bookmark from %q: %w", we.Object, err)
}
uw.setResourceVersion(bm.Metadata.ResourceVersion)
case "ERROR":
em, err := parseError(we.Object)
if err != nil {
return fmt.Errorf("cannot parse error message from %q: %w", we.Object, err)
}
if em.Code == 410 {
// See https://kubernetes.io/docs/reference/using-api/api-concepts/#410-gone-responses
uw.staleResourceVersions.Inc()
uw.setResourceVersion("")
return nil
}
return fmt.Errorf("unexpected error message: %q", we.Object)
default:
return fmt.Errorf("unexpected WatchEvent type %q: %q", we.Type, we.Object)
}
}
}
// Bookmark is a bookmark message from Kubernetes Watch API.
// See https://kubernetes.io/docs/reference/using-api/api-concepts/#watch-bookmarks
type Bookmark struct {
Metadata struct {
ResourceVersion string
}
}
func parseBookmark(data []byte) (*Bookmark, error) {
var bm Bookmark
if err := json.Unmarshal(data, &bm); err != nil {
return nil, err
}
return &bm, nil
}
// Error is an error message from Kubernetes Watch API.
type Error struct {
Code int
}
func parseError(data []byte) (*Error, error) {
var em Error
if err := json.Unmarshal(data, &em); err != nil {
return nil, err
}
return &em, nil
}
func getAPIPathsWithNamespaces(role string, namespaces []string, selectors []Selector) ([]string, []string) {
objectName := getObjectNameByRole(role)
if objectName == "nodes" || len(namespaces) == 0 {
query := joinSelectors(role, selectors)
path := getAPIPath(objectName, "", query)
return []string{path}, []string{""}
}
query := joinSelectors(role, selectors)
paths := make([]string, len(namespaces))
for i, namespace := range namespaces {
paths[i] = getAPIPath(objectName, namespace, query)
}
return paths, namespaces
}
func getAPIPath(objectName, namespace, query string) string {
suffix := objectName
if namespace != "" {
suffix = "namespaces/" + namespace + "/" + objectName
}
if len(query) > 0 {
suffix += "?" + query
}
if objectName == "ingresses" {
return "/apis/networking.k8s.io/v1beta1/" + suffix
}
if objectName == "endpointslices" {
return "/apis/discovery.k8s.io/v1beta1/" + suffix
}
return "/api/v1/" + suffix
}
func joinSelectors(role string, selectors []Selector) string {
var labelSelectors, fieldSelectors []string
for _, s := range selectors {
if s.Role != role {
continue
}
if s.Label != "" {
labelSelectors = append(labelSelectors, s.Label)
}
if s.Field != "" {
fieldSelectors = append(fieldSelectors, s.Field)
}
}
var args []string
if len(labelSelectors) > 0 {
args = append(args, "labelSelector="+url.QueryEscape(strings.Join(labelSelectors, ",")))
}
if len(fieldSelectors) > 0 {
args = append(args, "fieldSelector="+url.QueryEscape(strings.Join(fieldSelectors, ",")))
}
return strings.Join(args, "&")
}
func getObjectNameByRole(role string) string {
switch role {
case "node":
return "nodes"
case "pod":
return "pods"
case "service":
return "services"
case "endpoints":
return "endpoints"
case "endpointslices":
return "endpointslices"
case "ingress":
return "ingresses"
default:
logger.Panicf("BUG: unknonw role=%q", role)
return ""
}
}
func getObjectParsersForRole(role string) (parseObjectFunc, parseObjectListFunc) {
switch role {
case "node":
return parseNode, parseNodeList
case "pod":
return parsePod, parsePodList
case "service":
return parseService, parseServiceList
case "endpoints":
return parseEndpoints, parseEndpointsList
case "endpointslices":
return parseEndpointSlice, parseEndpointSliceList
case "ingress":
return parseIngress, parseIngressList
default:
logger.Panicf("BUG: unsupported role=%q", role)
return nil, nil
}
}