/
admission.go
183 lines (160 loc) · 4.86 KB
/
admission.go
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package admission
import (
"encoding/json"
"io"
"net/http"
"time"
"github.com/prometheus/client_golang/prometheus"
log "github.com/sirupsen/logrus"
)
const (
metricNamespace = "routegroup_admission"
metricSubsystem = "admitter"
)
var (
labels = []string{"admitter", "operation", "group", "version", "resource", "sub_resource"}
totalRequests = prometheus.NewCounterVec(prometheus.CounterOpts{
Namespace: metricNamespace,
Subsystem: metricSubsystem,
Name: "requests",
Help: "Total number of requests to this admitter",
}, []string{"admitter"})
invalidRequests = prometheus.NewCounterVec(prometheus.CounterOpts{
Namespace: metricNamespace,
Subsystem: metricSubsystem,
Name: "invalid_requests",
Help: "Total number of requests to this admitter that couldn't be parsed",
}, []string{"admitter"})
rejectedRequests = prometheus.NewCounterVec(prometheus.CounterOpts{
Namespace: metricNamespace,
Subsystem: metricSubsystem,
Name: "rejected_admissions",
Help: "Total number of requests rejected by this admitter",
}, labels)
approvedRequests = prometheus.NewCounterVec(prometheus.CounterOpts{
Namespace: metricNamespace,
Subsystem: metricSubsystem,
Name: "successful_admissions",
Help: "Total number of requests successfully processed by this admitter",
}, labels)
admissionDuration = prometheus.NewHistogramVec(prometheus.HistogramOpts{
Namespace: metricNamespace,
Subsystem: metricSubsystem,
Name: "admission_duration",
Help: "Duration of admission calls",
Buckets: []float64{.005, .01, .025, .05, .1, .25, .5, .75, 1, 1.25, 1.5, 2, 2.5, 5, 10},
}, labels)
)
type admitter interface {
name() string
admit(req *admissionRequest) (*admissionResponse, error)
}
func init() {
prometheus.MustRegister(totalRequests, invalidRequests, rejectedRequests, approvedRequests, admissionDuration)
}
func Handler(admitter admitter) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
admitterName := admitter.name()
totalRequests.WithLabelValues(admitterName).Inc()
if r.Method != "POST" || r.Header.Get("Content-Type") != "application/json" {
invalidRequests.WithLabelValues(admitterName).Inc()
w.WriteHeader(http.StatusBadRequest)
return
}
body, err := io.ReadAll(r.Body)
if err != nil {
log.Errorf("Failed to read request: %v", err)
w.WriteHeader(http.StatusInternalServerError)
invalidRequests.WithLabelValues(admitterName).Inc()
return
}
var review admissionReview
err = json.Unmarshal(body, &review)
if err != nil {
log.Errorf("Failed to parse request: %v", err)
w.WriteHeader(http.StatusBadRequest)
invalidRequests.WithLabelValues(admitterName).Inc()
return
}
request := review.Request
if request == nil {
log.Errorf("Missing review request")
w.WriteHeader(http.StatusBadRequest)
invalidRequests.WithLabelValues(admitterName).Inc()
return
}
log := log.WithFields(log.Fields{
"operation": request.Operation,
"kind": request.Kind,
"namespace": request.Namespace,
"name": extractName(request),
"user": request.UserInfo.Username,
})
gvr := request.Resource
group := gvr.Group
if group == "" {
group = "zalando.org"
}
labelValues := prometheus.Labels{
"admitter": admitterName,
"operation": request.Operation,
"group": group,
"version": gvr.Version,
"resource": gvr.Resource,
"sub_resource": request.SubResource,
}
start := time.Now()
defer func() {
admissionDuration.With(labelValues).Observe(float64(time.Since(start)) / float64(time.Second))
}()
admResp, err := admitter.admit(request)
if err != nil {
log.Errorf("Failed to admit request: %v", err)
w.WriteHeader(http.StatusBadRequest)
invalidRequests.WithLabelValues(admitterName).Inc()
return
}
if admResp.Allowed {
log.Debugf("Allowed")
approvedRequests.With(labelValues).Inc()
} else {
log.Debugf("Rejected")
rejectedRequests.With(labelValues).Inc()
}
writeResponse(w, admResp)
}
}
func writeResponse(writer http.ResponseWriter, response *admissionResponse) {
resp, err := json.Marshal(admissionReview{
typeMeta: typeMeta{
Kind: "AdmissionReview",
APIVersion: "admission.k8s.io/v1",
},
Response: response,
})
if err != nil {
log.Errorf("failed to serialize response: %v", err)
writer.WriteHeader(http.StatusInternalServerError)
return
}
if _, err := writer.Write(resp); err != nil {
log.Errorf("failed to write response: %v", err)
}
}
func extractName(request *admissionRequest) string {
if request.Name != "" {
return request.Name
}
obj := partialObjectMetadata{}
if err := json.Unmarshal(request.Object, &obj); err != nil {
log.Warnf("failed to parse object: %v", err)
return "<unknown>"
}
if obj.Name != "" {
return obj.Name
}
if obj.GenerateName != "" {
return obj.GenerateName + "<generated>"
}
return "<unknown>"
}