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webhook: add options to disable resource_namespace tag in metrics
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To add some context, historically, `resource_name` was removed from this
tag list due to its high potential of causing high metrics cardinality.
See [knative#1464][1] for more information.

While that's great, but it might not be sufficient for large scale use
cases where namespaces can be super dynamic (with generateName, too) or
grows fase enough. There is an issue report from
[tektoncd/pipeline#3171][2] which talks about this.

This proposal makes it possible to disable `resource_namespace` tag via
an option function. The default behavior is not changed, so no user
impact if any of existing users rely on this tag. There is no API
contract change either due to the beauty of variadic functions.

Now downstream projects can consume this by override `StatsReporter` in
webhook context options with their own preference. As a caveat here, if
downstream project does choose to override `StatsReporter`, the default
`ReportMetrics` function shouldn't be called by default as they may now
have a different set of tag keys to report. As such, this function is
only called if the default `StatsReporter` is used.

[1]: knative#1464
[2]: tektoncd/pipeline#3171
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@zhouhaibing089
zhouhaibing089 committed Mar 10, 2024
1 parent 6b13f01 commit cb50ed6
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Showing 2 changed files with 155 additions and 41 deletions.
147 changes: 110 additions & 37 deletions webhook/stats_reporter.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -65,43 +65,111 @@ var (
resultCodeKey = tag.MustNewKey("result_code")
)

type admissionToValue func(*admissionv1.AdmissionRequest, *admissionv1.AdmissionResponse) string
type conversionToValue func(*apixv1.ConversionRequest, *apixv1.ConversionResponse) string

var (
admissionTags = map[tag.Key]admissionToValue{
requestOperationKey: func(req *admissionv1.AdmissionRequest, _ *admissionv1.AdmissionResponse) string {
return string(req.Operation)
},
kindGroupKey: func(req *admissionv1.AdmissionRequest, _ *admissionv1.AdmissionResponse) string {
return req.Kind.Group
},
kindVersionKey: func(req *admissionv1.AdmissionRequest, _ *admissionv1.AdmissionResponse) string {
return req.Kind.Version
},
kindKindKey: func(req *admissionv1.AdmissionRequest, _ *admissionv1.AdmissionResponse) string {
return req.Kind.Kind
},
resourceGroupKey: func(req *admissionv1.AdmissionRequest, _ *admissionv1.AdmissionResponse) string {
return req.Resource.Group
},
resourceVersionKey: func(req *admissionv1.AdmissionRequest, _ *admissionv1.AdmissionResponse) string {
return req.Resource.Version
},
resourceResourceKey: func(req *admissionv1.AdmissionRequest, _ *admissionv1.AdmissionResponse) string {
return req.Resource.Resource
},
resourceNamespaceKey: func(req *admissionv1.AdmissionRequest, _ *admissionv1.AdmissionResponse) string {
return req.Namespace
},
admissionAllowedKey: func(_ *admissionv1.AdmissionRequest, resp *admissionv1.AdmissionResponse) string {
return strconv.FormatBool(resp.Allowed)
},
}
conversionTags = map[tag.Key]conversionToValue{
desiredAPIVersionKey: func(req *apixv1.ConversionRequest, _ *apixv1.ConversionResponse) string {
return req.DesiredAPIVersion
},
resultStatusKey: func(_ *apixv1.ConversionRequest, resp *apixv1.ConversionResponse) string {
return resp.Result.Status
},
resultReasonKey: func(_ *apixv1.ConversionRequest, resp *apixv1.ConversionResponse) string {
return string(resp.Result.Reason)
},
resultCodeKey: func(_ *apixv1.ConversionRequest, resp *apixv1.ConversionResponse) string {
return strconv.Itoa(int(resp.Result.Code))
},
}
)

// StatsReporter reports webhook metrics
type StatsReporter interface {
ReportAdmissionRequest(request *admissionv1.AdmissionRequest, response *admissionv1.AdmissionResponse, d time.Duration) error
ReportConversionRequest(request *apixv1.ConversionRequest, response *apixv1.ConversionResponse, d time.Duration) error
}

type options struct {
tagsToExclude map[string]struct{}
}

type Option func(_ *options)

func WithoutTag(tag string) Option {
return func(opts *options) {
if opts.tagsToExclude == nil {
opts.tagsToExclude = make(map[string]struct{})
}
opts.tagsToExclude[tag] = struct{}{}
}
}

// reporter implements StatsReporter interface
type reporter struct {
ctx context.Context
ctx context.Context
opts options
}

// NewStatsReporter creates a reporter for webhook metrics
func NewStatsReporter() (StatsReporter, error) {
func NewStatsReporter(opts ...Option) (StatsReporter, error) {
ctx, err := tag.New(
context.Background(),
)
if err != nil {
return nil, err
}

return &reporter{ctx: ctx}, nil
options := options{}
for _, opt := range opts {
opt(&options)
}

return &reporter{ctx: ctx, opts: options}, nil
}

// Captures req count metric, recording the count and the duration
func (r *reporter) ReportAdmissionRequest(req *admissionv1.AdmissionRequest, resp *admissionv1.AdmissionResponse, d time.Duration) error {
ctx, err := tag.New(
r.ctx,
tag.Insert(requestOperationKey, string(req.Operation)),
tag.Insert(kindGroupKey, req.Kind.Group),
tag.Insert(kindVersionKey, req.Kind.Version),
tag.Insert(kindKindKey, req.Kind.Kind),
tag.Insert(resourceGroupKey, req.Resource.Group),
tag.Insert(resourceVersionKey, req.Resource.Version),
tag.Insert(resourceResourceKey, req.Resource.Resource),
tag.Insert(resourceNamespaceKey, req.Namespace),
tag.Insert(admissionAllowedKey, strconv.FormatBool(resp.Allowed)),
)
mutators := []tag.Mutator{}

for key, f := range admissionTags {
if _, ok := r.opts.tagsToExclude[key.Name()]; ok {
continue
}
mutators = append(mutators, tag.Insert(key, f(req, resp)))
}

ctx, err := tag.New(r.ctx, mutators...)
if err != nil {
return err
}
Expand All @@ -114,13 +182,16 @@ func (r *reporter) ReportAdmissionRequest(req *admissionv1.AdmissionRequest, res

// Captures req count metric, recording the count and the duration
func (r *reporter) ReportConversionRequest(req *apixv1.ConversionRequest, resp *apixv1.ConversionResponse, d time.Duration) error {
ctx, err := tag.New(
r.ctx,
tag.Insert(desiredAPIVersionKey, req.DesiredAPIVersion),
tag.Insert(resultStatusKey, resp.Result.Status),
tag.Insert(resultReasonKey, string(resp.Result.Reason)),
tag.Insert(resultCodeKey, strconv.Itoa(int(resp.Result.Code))),
)
mutators := []tag.Mutator{}

for key, f := range conversionTags {
if _, ok := r.opts.tagsToExclude[key.Name()]; ok {
continue
}
mutators = append(mutators, tag.Insert(key, f(req, resp)))
}

ctx, err := tag.New(r.ctx, mutators...)
if err != nil {
return err
}
Expand All @@ -131,21 +202,23 @@ func (r *reporter) ReportConversionRequest(req *apixv1.ConversionRequest, resp *
return nil
}

func RegisterMetrics() {
tagKeys := []tag.Key{
requestOperationKey,
kindGroupKey,
kindVersionKey,
kindKindKey,
resourceGroupKey,
resourceVersionKey,
resourceResourceKey,
resourceNamespaceKey,
admissionAllowedKey,
desiredAPIVersionKey,
resultStatusKey,
resultReasonKey,
resultCodeKey}
func RegisterMetrics(opts ...Option) {
options := options{}
for _, opt := range opts {
opt(&options)
}

tagKeys := []tag.Key{}
for tag := range admissionTags {
if _, ok := options.tagsToExclude[tag.Name()]; !ok {
tagKeys = append(tagKeys, tag)
}
}
for tag := range conversionTags {
if _, ok := options.tagsToExclude[tag.Name()]; !ok {
tagKeys = append(tagKeys, tag)
}
}

if err := view.Register(
&view.View{
Expand Down
49 changes: 45 additions & 4 deletions webhook/stats_reporter_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -70,6 +70,47 @@ func TestWebhookStatsReporterAdmission(t *testing.T) {
metricstest.CheckDistributionData(t, requestLatenciesName, expectedTags, 2, shortTime, longTime)
}

func TestWebhookStatsReporterAdmissionWithoutNamespaceTag(t *testing.T) {
setup(WithoutTag(resourceNamespaceKey.Name()))
req := &admissionv1.AdmissionRequest{
UID: "705ab4f5-6393-11e8-b7cc-42010a800002",
Kind: metav1.GroupVersionKind{Group: "autoscaling", Version: "v1", Kind: "Scale"},
Resource: metav1.GroupVersionResource{Group: "apps", Version: "v1", Resource: "deployments"},
Name: "my-deployment",
Namespace: "my-namespace",
Operation: admissionv1.Update,
}

resp := &admissionv1.AdmissionResponse{
UID: req.UID,
Allowed: true,
}

r, _ := NewStatsReporter(WithoutTag(resourceNamespaceKey.Name()))

shortTime, longTime := 1100.0, 9100.0
expectedTags := map[string]string{
requestOperationKey.Name(): string(req.Operation),
kindGroupKey.Name(): req.Kind.Group,
kindVersionKey.Name(): req.Kind.Version,
kindKindKey.Name(): req.Kind.Kind,
resourceGroupKey.Name(): req.Resource.Group,
resourceVersionKey.Name(): req.Resource.Version,
resourceResourceKey.Name(): req.Resource.Resource,
admissionAllowedKey.Name(): strconv.FormatBool(resp.Allowed),
}

if err := r.ReportAdmissionRequest(req, resp, time.Duration(shortTime)*time.Millisecond); err != nil {
t.Fatalf("ReportAdmissionRequest() = %v", err)
}
if err := r.ReportAdmissionRequest(req, resp, time.Duration(longTime)*time.Millisecond); err != nil {
t.Fatalf("ReportAdmissionRequest() = %v", err)
}

metricstest.CheckCountData(t, requestCountName, expectedTags, 2)
metricstest.CheckDistributionData(t, requestLatenciesName, expectedTags, 2, shortTime, longTime)
}

func TestWebhookStatsReporterConversion(t *testing.T) {
setup()
req := &apixv1.ConversionRequest{
Expand Down Expand Up @@ -103,12 +144,12 @@ func TestWebhookStatsReporterConversion(t *testing.T) {
metricstest.CheckDistributionData(t, requestLatenciesName, expectedTags, 2, shortTime, longTime)
}

func setup() {
resetMetrics()
func setup(opts ...Option) {
resetMetrics(opts...)
}

// opencensus metrics carry global state that need to be reset between unit tests
func resetMetrics() {
func resetMetrics(opts ...Option) {
metricstest.Unregister(requestCountName, requestLatenciesName)
RegisterMetrics()
RegisterMetrics(opts...)
}

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