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package otelginmetrics
import (
"net/http"
"time"
"github.com/gin-gonic/gin"
semconv "go.opentelemetry.io/otel/semconv/v1.7.0"
)
// Middleware returns middleware that will trace incoming requests.
// The service parameter should describe the name of the (virtual)
// server handling the request.
func Middleware(service string, options ...Option) gin.HandlerFunc {
cfg := defaultConfig()
for _, option := range options {
option.apply(cfg)
}
recorder := cfg.recorder
if recorder == nil {
recorder = GetRecorder("")
}
return func(ginCtx *gin.Context) {
ctx := ginCtx.Request.Context()
route := ginCtx.FullPath()
if len(route) <= 0 {
route = "nonconfigured"
}
if !cfg.shouldRecord(service, route, ginCtx.Request) {
ginCtx.Next()
return
}
start := time.Now()
reqAttributes := cfg.attributes(service, route, ginCtx.Request)
if cfg.recordInFlight {
recorder.AddInflightRequests(ctx, 1, reqAttributes)
defer recorder.AddInflightRequests(ctx, -1, reqAttributes)
}
defer func() {
resAttributes := append(reqAttributes[0:0], reqAttributes...)
if cfg.groupedStatus {
code := int(ginCtx.Writer.Status()/100) * 100
resAttributes = append(resAttributes, semconv.HTTPStatusCodeKey.Int(code))
} else {
resAttributes = append(resAttributes, semconv.HTTPAttributesFromHTTPStatusCode(ginCtx.Writer.Status())...)
}
recorder.AddRequests(ctx, 1, resAttributes)
if cfg.recordSize {
requestSize := computeApproximateRequestSize(ginCtx.Request)
recorder.ObserveHTTPRequestSize(ctx, requestSize, resAttributes)
recorder.ObserveHTTPResponseSize(ctx, int64(ginCtx.Writer.Size()), resAttributes)
}
if cfg.recordDuration {
recorder.ObserveHTTPRequestDuration(ctx, time.Since(start), resAttributes)
}
}()
ginCtx.Next()
}
}
func computeApproximateRequestSize(r *http.Request) int64 {
s := 0
if r.URL != nil {
s = len(r.URL.Path)
}
s += len(r.Method)
s += len(r.Proto)
for name, values := range r.Header {
s += len(name)
for _, value := range values {
s += len(value)
}
}
s += len(r.Host)
// N.B. r.Form and r.MultipartForm are assumed to be included in r.URL.
if r.ContentLength != -1 {
s += int(r.ContentLength)
}
return int64(s)
}
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