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// GoToSocial
// Copyright (C) GoToSocial Authors admin@gotosocial.org
// SPDX-License-Identifier: AGPL-3.0-or-later
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
//go:build !nootel
package observability
import (
"net/http"
"slices"
"time"
"code.superseriousbusiness.org/gotosocial/internal/config"
"github.com/gin-gonic/gin"
"go.opentelemetry.io/otel"
"go.opentelemetry.io/otel/attribute"
"go.opentelemetry.io/otel/metric"
semconv "go.opentelemetry.io/otel/semconv/v1.7.0"
)
// ginMiddleware returns a middleware that
// records metrics for incoming requests.
func ginMiddleware() gin.HandlerFunc {
meter := otel.Meter("gin", metric.WithInstrumentationVersion(config.GetSoftwareVersion()))
activeReqs, _ := meter.Int64UpDownCounter(
"http.server.requests_active",
metric.WithDescription("Number of requests currently active"),
)
totalReqs, _ := meter.Int64Counter(
"http.server.requests",
metric.WithDescription("Total number of requests served"),
)
reqSize, _ := meter.Int64Histogram(
"http.server.request_size",
metric.WithDescription("Request content length (approximate)"),
metric.WithUnit("bytes"),
)
respSize, _ := meter.Int64Histogram(
"http.server.response_size",
metric.WithDescription("Response content length"),
metric.WithUnit("bytes"),
)
duration, _ := meter.Int64Histogram(
"http.server.duration",
metric.WithDescription("Duration of request -> response"),
metric.WithUnit("ms"),
)
return func(c *gin.Context) {
ctx := c.Request.Context()
route := c.FullPath()
start := time.Now()
// Generate request attributes.
reqAttributes := []attribute.KeyValue{
semconv.HTTPServerNameKey.String("GoToSocial"),
semconv.HTTPMethodKey.String(c.Request.Method),
semconv.HTTPRouteKey.String(route),
}
// Increment active request count,
// decrement again when we're finished.
activeReqs.Add(ctx, 1, metric.WithAttributes(reqAttributes...))
defer activeReqs.Add(ctx, -1, metric.WithAttributes(reqAttributes...))
// Process request so we can
// record response metrics.
c.Next()
// Add HTTP response code to request
// attributes to create response attributes.
respAttributes := slices.Clone(reqAttributes)
respAttributes = append(
respAttributes,
semconv.HTTPStatusCodeKey.Int(c.Writer.Status()),
)
// Increment total requests.
totalReqs.Add(ctx, 1, metric.WithAttributes(respAttributes...))
// Record request size.
reqSize.Record(
ctx,
computeApproximateRequestSize(c.Request),
metric.WithAttributes(respAttributes...),
)
// Record response size.
respSize.Record(
ctx,
int64(c.Writer.Size()),
metric.WithAttributes(respAttributes...),
)
// Record req + resp duration.
duration.Record(
ctx,
time.Since(start).Milliseconds(),
metric.WithAttributes(respAttributes...),
)
}
}
func computeApproximateRequestSize(r *http.Request) (sz int64) {
len := func(s string) int64 { return int64(len(s)) }
// First line
sz += len(r.Method)
if r.URL != nil {
sz += len(r.URL.Path)
sz++ // for '?'
sz += len(r.URL.RawQuery)
sz += len(r.URL.RawFragment)
}
sz += len(r.Proto)
sz += 2 // for '\r\n'
// Next are lines for request headers.
for name, values := range r.Header {
// Each value on its own line.
for _, value := range values {
sz += len(name)
sz += len(value)
sz += 2 // for '\r\n'
}
}
// Finally, any request body (if set),
// this includes (multipart) form data.
sz += max(r.ContentLength, 0)
return
}
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