Open telemetry integration (#3972)

This PR adds opentelemetry and chi wrapper to have basic instrumentation

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## Draft release notes
<!--URL:https://codeberg.org/forgejo/forgejo-->
- Features
  - [PR](https://codeberg.org/forgejo/forgejo/pulls/3972): <!--number 3972 --><!--line 0 --><!--description YWRkIHN1cHBvcnQgZm9yIGJhc2ljIHJlcXVlc3QgdHJhY2luZyB3aXRoIG9wZW50ZWxlbWV0cnk=-->add support for basic request tracing with opentelemetry<!--description-->
<!--end release-notes-assistant-->

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/3972
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Co-authored-by: TheFox0x7 <thefox0x7@gmail.com>
Co-committed-by: TheFox0x7 <thefox0x7@gmail.com>

routers/common/middleware.go

@@ -18,6 +18,7 @@ import (
 	"gitea.com/go-chi/session"
 	"github.com/chi-middleware/proxy"
 	chi "github.com/go-chi/chi/v5"
+	"github.com/riandyrn/otelchi"
 )
 
 // ProtocolMiddlewares returns HTTP protocol related middlewares, and it provides a global panic recovery
@@ -68,6 +69,9 @@ func ProtocolMiddlewares() (handlers []any) {
 	if setting.IsAccessLogEnabled() {
 		handlers = append(handlers, context.AccessLogger())
 	}
+	if setting.IsOpenTelemetryEnabled() {
+		handlers = append(handlers, otelchi.Middleware("forgejo"))
+	}
 
 	return handlers
 }

routers/init.go

@@ -18,6 +18,7 @@ import (
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/markup"
 	"code.gitea.io/gitea/modules/markup/external"
+	"code.gitea.io/gitea/modules/opentelemetry"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/ssh"
 	"code.gitea.io/gitea/modules/storage"
@@ -110,6 +111,7 @@ func InitWebInstallPage(ctx context.Context) {
 
 // InitWebInstalled is for global installed configuration.
 func InitWebInstalled(ctx context.Context) {
+	mustInitCtx(ctx, opentelemetry.Init)
 	mustInitCtx(ctx, git.InitFull)
 	log.Info("Git version: %s (home: %s)", git.VersionInfo(), git.HomeDir())
 

routers/install/routes_test.go

@@ -4,12 +4,23 @@
 package install
 
 import (
+	"context"
+	"io"
+	"net/http"
 	"net/http/httptest"
+	"net/url"
+	"os"
 	"testing"
+	"time"
 
 	"code.gitea.io/gitea/models/unittest"
+	"code.gitea.io/gitea/modules/opentelemetry"
+	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/test"
 
+	"github.com/google/uuid"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestRoutes(t *testing.T) {
@@ -36,3 +47,43 @@ func TestRoutes(t *testing.T) {
 func TestMain(m *testing.M) {
 	unittest.MainTest(m)
 }
+
+func TestOtelChi(t *testing.T) {
+	ServiceName := "forgejo-otelchi" + uuid.NewString()
+
+	otelURL, ok := os.LookupEnv("TEST_OTEL_URL")
+	if !ok {
+		t.Skip("TEST_OTEL_URL not set")
+	}
+	traceEndpoint, err := url.Parse(otelURL)
+	require.NoError(t, err)
+	config := &setting.OtelExporter{
+		Endpoint: traceEndpoint,
+		Protocol: "grpc",
+	}
+
+	defer test.MockVariableValue(&setting.OpenTelemetry.Enabled, true)()
+	defer test.MockVariableValue(&setting.OpenTelemetry.Traces, "otlp")() // Required due to lazy loading
+	defer test.MockVariableValue(&setting.OpenTelemetry.ServiceName, ServiceName)()
+	defer test.MockVariableValue(&setting.OpenTelemetry.OtelTraces, config)()
+
+	require.NoError(t, opentelemetry.Init(context.Background()))
+	r := Routes()
+
+	w := httptest.NewRecorder()
+	req := httptest.NewRequest("GET", "/e/img/gitea.svg", nil)
+	r.ServeHTTP(w, req)
+
+	traceEndpoint.Host = traceEndpoint.Hostname() + ":16686"
+	traceEndpoint.Path = "/api/services"
+
+	require.EventuallyWithT(t, func(collect *assert.CollectT) {
+		resp, err := http.Get(traceEndpoint.String())
+		require.NoError(t, err)
+
+		apiResponse, err := io.ReadAll(resp.Body)
+		require.NoError(t, err)
+
+		assert.Contains(collect, string(apiResponse), ServiceName)
+	}, 15*time.Second, 1*time.Second)
+}