Add tracing and relevant tests (#21)

* Add tracing and relevant tests.

* fixup! Add tracing and relevant tests.

* gofmt the code 🤷

* fixup! gofmt the code 🤷

README.md

@@ -14,6 +14,7 @@ This project is in active use by [telegram-bot.app](https://telegram-bot.app), a
   - [Endpoints](#endpoints)
   - [Features](#features)
   - [Configuration](#configuration)
+  - [Tracing](#tracing)
   - [Speed](#speed)
     - [Caching](#caching)
     - [Read-only endpoint](#read-only-endpoint)
@@ -107,6 +108,7 @@ In this case, both proxy and websockets will be available under the `/v1/graphql
 | monitor    | Extracting user id from JWT token and adding it as a label to metrics |
 | monitor    | Extracting the query name and type and adding it as a label to metrics|
 | monitor    | Calculating the query duration and adding it to the metrics           |
+| monitor    | OpenTelemetry tracing support with configurable endpoint              |
 | speed      | Caching the queries, together with per-query cache and TTL            |
 | speed      | Support for READ ONLY graphql endpoint                                |
 | security   | Blocking schema introspection                                         |
@@ -155,6 +157,26 @@ You can still use the non-prefixed environment variables in the spirit of the ba
 | `HASURA_EVENT_CLEANER`   | Enable the hasura event cleaner          | `false`                    |
 | `HASURA_EVENT_CLEANER_OLDER_THAN` | The interval for the hasura event cleaner (in days) | `1`                  |
 | `HASURA_EVENT_METADATA_DB` | URL to the hasura metadata database    | `postgresql://localhost:5432/hasura` |
+| `ENABLE_TRACE`            | Enable OpenTelemetry tracing           | `false`                    |
+| `TRACE_ENDPOINT`          | OpenTelemetry collector endpoint       | `localhost:4317`           |
+
+### Tracing
+
+The proxy supports OpenTelemetry tracing to help monitor and debug requests. When enabled, it will create spans for each proxied request and send them to the configured OpenTelemetry collector.
+
+To use tracing:
+
+1. Enable tracing by setting `ENABLE_TRACE=true`
+2. Configure the OpenTelemetry collector endpoint using `TRACE_ENDPOINT` (defaults to `localhost:4317`)
+3. Include trace context in your requests using the `X-Trace-Span` header with the following format:
+
+```json
+{
+  "traceparent": "00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-01"
+}
+```
+
+The proxy will extract the trace context from the header and create child spans for each request, allowing you to trace requests through your system.
 
 ### Speed
 

go.mod

@@ -1,6 +1,8 @@
 module github.com/lukaszraczylo/graphql-monitoring-proxy
 
-go 1.22.4
+go 1.22.7
+
+toolchain go1.23.4
 
 require (
 	github.com/VictoriaMetrics/metrics v1.35.1
@@ -17,39 +19,53 @@ require (
 	github.com/lukaszraczylo/go-ratecounter v0.1.12
 	github.com/lukaszraczylo/go-simple-graphql v1.2.37
 	github.com/redis/go-redis/v9 v9.7.0
-	github.com/stretchr/testify v1.9.0
+	github.com/stretchr/testify v1.10.0
 	github.com/valyala/fasthttp v1.58.0
+	go.opentelemetry.io/otel v1.33.0
+	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.33.0
+	go.opentelemetry.io/otel/sdk v1.33.0
+	go.opentelemetry.io/otel/trace v1.33.0
+	google.golang.org/grpc v1.69.2
 )
 
 require (
 	github.com/alicebob/gopher-json v0.0.0-20200520072559-a9ecdc9d1d3a // indirect
 	github.com/andybalholm/brotli v1.1.1 // indirect
+	github.com/cenkalti/backoff/v4 v4.3.0 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f // indirect
+	github.com/go-logr/logr v1.4.2 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/gookit/color v1.5.4 // indirect
+	github.com/grpc-ecosystem/grpc-gateway/v2 v2.25.1 // indirect
 	github.com/jackc/pgpassfile v1.0.0 // indirect
 	github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 // indirect
 	github.com/jackc/puddle/v2 v2.2.2 // indirect
 	github.com/klauspost/compress v1.17.11 // indirect
-	github.com/kr/text v0.2.0 // indirect
 	github.com/mattn/go-colorable v0.1.13 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/mattn/go-runewidth v0.0.16 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/rivo/uniseg v0.4.7 // indirect
-	github.com/rogpeppe/go-internal v1.12.0 // indirect
 	github.com/valyala/bytebufferpool v1.0.0 // indirect
 	github.com/valyala/fastrand v1.1.0 // indirect
 	github.com/valyala/histogram v1.2.0 // indirect
 	github.com/valyala/tcplisten v1.0.0 // indirect
 	github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e // indirect
 	github.com/yuin/gopher-lua v1.1.1 // indirect
+	go.opentelemetry.io/auto/sdk v1.1.0 // indirect
+	go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.33.0 // indirect
+	go.opentelemetry.io/otel/metric v1.33.0 // indirect
+	go.opentelemetry.io/proto/otlp v1.5.0 // indirect
 	golang.org/x/crypto v0.32.0 // indirect
 	golang.org/x/net v0.34.0 // indirect
 	golang.org/x/sync v0.10.0 // indirect
 	golang.org/x/sys v0.29.0 // indirect
 	golang.org/x/term v0.28.0 // indirect
 	golang.org/x/text v0.21.0 // indirect
+	google.golang.org/genproto/googleapis/api v0.0.0-20250106144421-5f5ef82da422 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20250106144421-5f5ef82da422 // indirect
+	google.golang.org/protobuf v1.36.2 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -12,14 +12,20 @@ github.com/bsm/ginkgo/v2 v2.12.0 h1:Ny8MWAHyOepLGlLKYmXG4IEkioBysk6GpaRTLC8zwWs=
 github.com/bsm/ginkgo/v2 v2.12.0/go.mod h1:SwYbGRRDovPVboqFv0tPTcG1sN61LM1Z4ARdbAV9g4c=
 github.com/bsm/gomega v1.27.10 h1:yeMWxP2pV2fG3FgAODIY8EiRE3dy0aeFYt4l7wh6yKA=
 github.com/bsm/gomega v1.27.10/go.mod h1:JyEr/xRbxbtgWNi8tIEVPUYZ5Dzef52k01W3YH0H+O0=
+github.com/cenkalti/backoff/v4 v4.3.0 h1:MyRJ/UdXutAwSAT+s3wNd7MfTIcy71VQueUuFK343L8=
+github.com/cenkalti/backoff/v4 v4.3.0/go.mod h1:Y3VNntkOUPxTVeUxJ/G5vcM//AlwfmyYozVcomhLiZE=
 github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
 github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
-github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f h1:lO4WD4F/rVNCu3HqELle0jiPLLBs70cWOduZpkS1E78=
 github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f/go.mod h1:cuUVRXasLTGF7a8hSLbxyZXjz+1KgoB3wDUb6vlszIc=
+github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
+github.com/go-logr/logr v1.4.2 h1:6pFjapn8bFcIbiKo3XT4j/BhANplGihG6tvd+8rYgrY=
+github.com/go-logr/logr v1.4.2/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
+github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
+github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
 github.com/goccy/go-json v0.10.4 h1:JSwxQzIqKfmFX1swYPpUThQZp/Ka4wzJdK0LWVytLPM=
 github.com/goccy/go-json v0.10.4/go.mod h1:oq7eo15ShAhp70Anwd5lgX2pLfOS3QCiwU/PULtXL6M=
 github.com/goccy/go-reflect v1.2.0 h1:O0T8rZCuNmGXewnATuKYnkL0xm6o8UNOJZd/gOkb9ms=
@@ -28,6 +34,10 @@ github.com/gofiber/fiber/v2 v2.52.6 h1:Rfp+ILPiYSvvVuIPvxrBns+HJp8qGLDnLJawAu27X
 github.com/gofiber/fiber/v2 v2.52.6/go.mod h1:YEcBbO/FB+5M1IZNBP9FO3J9281zgPAreiI1oqg8nDw=
 github.com/gofrs/flock v0.12.1 h1:MTLVXXHf8ekldpJk3AKicLij9MdwOWkZ+a/jHHZby9E=
 github.com/gofrs/flock v0.12.1/go.mod h1:9zxTsyu5xtJ9DK+1tFZyibEV7y3uwDxPPfbxeeHCoD0=
+github.com/golang/protobuf v1.5.4 h1:i7eJL8qZTpSEXOPTxNKhASYpMn+8e5Q6AdndVa1dWek=
+github.com/golang/protobuf v1.5.4/go.mod h1:lnTiLA8Wa4RWRcIUkrtSVa5nRhsEGBg48fD6rSs7xps=
+github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
+github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/gookit/color v1.5.4 h1:FZmqs7XOyGgCAxmWyPslpiok1k05wmY3SJTytgvYFs0=
@@ -36,6 +46,8 @@ github.com/gookit/goutil v0.6.18 h1:MUVj0G16flubWT8zYVicIuisUiHdgirPAkmnfD2kKgw=
 github.com/gookit/goutil v0.6.18/go.mod h1:AY/5sAwKe7Xck+mEbuxj0n/bc3qwrGNe3Oeulln7zBA=
 github.com/graphql-go/graphql v0.8.1 h1:p7/Ou/WpmulocJeEx7wjQy611rtXGQaAcXGqanuMMgc=
 github.com/graphql-go/graphql v0.8.1/go.mod h1:nKiHzRM0qopJEwCITUuIsxk9PlVlwIiiI8pnJEhordQ=
+github.com/grpc-ecosystem/grpc-gateway/v2 v2.25.1 h1:VNqngBF40hVlDloBruUehVYC3ArSgIyScOAyMRqBxRg=
+github.com/grpc-ecosystem/grpc-gateway/v2 v2.25.1/go.mod h1:RBRO7fro65R6tjKzYgLAFo0t1QEXY1Dp+i/bvpRiqiQ=
 github.com/jackc/pgpassfile v1.0.0 h1:/6Hmqy13Ss2zCq62VdNG8tM1wchn8zjSGOBJ6icpsIM=
 github.com/jackc/pgpassfile v1.0.0/go.mod h1:CEx0iS5ambNFdcRtxPj5JhEz+xB6uRky5eyVu/W2HEg=
 github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 h1:iCEnooe7UlwOQYpKFhBabPMi4aNAfoODPEFNiAnClxo=
@@ -70,13 +82,13 @@ github.com/redis/go-redis/v9 v9.7.0/go.mod h1:f6zhXITC7JUJIlPEiBOTXxJgPLdZcA93Ge
 github.com/rivo/uniseg v0.2.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
 github.com/rivo/uniseg v0.4.7 h1:WUdvkW8uEhrYfLC4ZzdpI2ztxP1I582+49Oc5Mq64VQ=
 github.com/rivo/uniseg v0.4.7/go.mod h1:FN3SvrM+Zdj16jyLfmOkMNblXMcoc8DfTHruCPUcx88=
-github.com/rogpeppe/go-internal v1.12.0 h1:exVL4IDcn6na9z1rAb56Vxr+CgyK3nn3O+epU5NdKM8=
+github.com/rogpeppe/go-internal v1.13.1 h1:KvO1DLK/DRN07sQ1LQKScxyZJuNnedQ5/wKSR38lUII=
-github.com/rogpeppe/go-internal v1.12.0/go.mod h1:E+RYuTGaKKdloAfM02xzb0FW3Paa99yedzYV+kq4uf4=
+github.com/rogpeppe/go-internal v1.13.1/go.mod h1:uMEvuHeurkdAXX61udpOXGD/AzZDWNMNyH2VO9fmH0o=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
+github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
-github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 github.com/valyala/bytebufferpool v1.0.0 h1:GqA5TC/0021Y/b9FG4Oi9Mr3q7XYx6KllzawFIhcdPw=
 github.com/valyala/bytebufferpool v1.0.0/go.mod h1:6bBcMArwyJ5K/AmCkWv1jt77kVWyCJ6HpOuEn7z0Csc=
 github.com/valyala/fasthttp v1.58.0 h1:GGB2dWxSbEprU9j0iMJHgdKYJVDyjrOwF9RE59PbRuE=
@@ -93,6 +105,26 @@ github.com/xyproto/randomstring v1.0.5 h1:YtlWPoRdgMu3NZtP45drfy1GKoojuR7hmRcnhZ
 github.com/xyproto/randomstring v1.0.5/go.mod h1:rgmS5DeNXLivK7YprL0pY+lTuhNQW3iGxZ18UQApw/E=
 github.com/yuin/gopher-lua v1.1.1 h1:kYKnWBjvbNP4XLT3+bPEwAXJx262OhaHDWDVOPjL46M=
 github.com/yuin/gopher-lua v1.1.1/go.mod h1:GBR0iDaNXjAgGg9zfCvksxSRnQx76gclCIb7kdAd1Pw=
+go.opentelemetry.io/auto/sdk v1.1.0 h1:cH53jehLUN6UFLY71z+NDOiNJqDdPRaXzTel0sJySYA=
+go.opentelemetry.io/auto/sdk v1.1.0/go.mod h1:3wSPjt5PWp2RhlCcmmOial7AvC4DQqZb7a7wCow3W8A=
+go.opentelemetry.io/otel v1.33.0 h1:/FerN9bax5LoK51X/sI0SVYrjSE0/yUL7DpxW4K3FWw=
+go.opentelemetry.io/otel v1.33.0/go.mod h1:SUUkR6csvUQl+yjReHu5uM3EtVV7MBm5FHKRlNx4I8I=
+go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.33.0 h1:Vh5HayB/0HHfOQA7Ctx69E/Y/DcQSMPpKANYVMQ7fBA=
+go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.33.0/go.mod h1:cpgtDBaqD/6ok/UG0jT15/uKjAY8mRA53diogHBg3UI=
+go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.33.0 h1:5pojmb1U1AogINhN3SurB+zm/nIcusopeBNp42f45QM=
+go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.33.0/go.mod h1:57gTHJSE5S1tqg+EKsLPlTWhpHMsWlVmer+LA926XiA=
+go.opentelemetry.io/otel/metric v1.33.0 h1:r+JOocAyeRVXD8lZpjdQjzMadVZp2M4WmQ+5WtEnklQ=
+go.opentelemetry.io/otel/metric v1.33.0/go.mod h1:L9+Fyctbp6HFTddIxClbQkjtubW6O9QS3Ann/M82u6M=
+go.opentelemetry.io/otel/sdk v1.33.0 h1:iax7M131HuAm9QkZotNHEfstof92xM+N8sr3uHXc2IM=
+go.opentelemetry.io/otel/sdk v1.33.0/go.mod h1:A1Q5oi7/9XaMlIWzPSxLRWOI8nG3FnzHJNbiENQuihM=
+go.opentelemetry.io/otel/sdk/metric v1.31.0 h1:i9hxxLJF/9kkvfHppyLL55aW7iIJz4JjxTeYusH7zMc=
+go.opentelemetry.io/otel/sdk/metric v1.31.0/go.mod h1:CRInTMVvNhUKgSAMbKyTMxqOBC0zgyxzW55lZzX43Y8=
+go.opentelemetry.io/otel/trace v1.33.0 h1:cCJuF7LRjUFso9LPnEAHJDB2pqzp+hbO8eu1qqW2d/s=
+go.opentelemetry.io/otel/trace v1.33.0/go.mod h1:uIcdVUZMpTAmz0tI1z04GoVSezK37CbGV4fr1f2nBck=
+go.opentelemetry.io/proto/otlp v1.5.0 h1:xJvq7gMzB31/d406fB8U5CBdyQGw4P399D1aQWU/3i4=
+go.opentelemetry.io/proto/otlp v1.5.0/go.mod h1:keN8WnHxOy8PG0rQZjJJ5A2ebUoafqWp0eVQ4yIXvJ4=
+go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
+go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
 golang.org/x/crypto v0.32.0 h1:euUpcYgM8WcP71gNpTqQCn6rC2t6ULUPiOzfWaXVVfc=
 golang.org/x/crypto v0.32.0/go.mod h1:ZnnJkOaASj8g0AjIduWNlq2NRxL0PlBrbKVyZ6V/Ugc=
 golang.org/x/exp v0.0.0-20220909182711-5c715a9e8561 h1:MDc5xs78ZrZr3HMQugiXOAkSZtfTpbJLDr/lwfgO53E=
@@ -109,6 +141,14 @@ golang.org/x/term v0.28.0 h1:/Ts8HFuMR2E6IP/jlo7QVLZHggjKQbhu/7H0LJFr3Gg=
 golang.org/x/term v0.28.0/go.mod h1:Sw/lC2IAUZ92udQNf3WodGtn4k/XoLyZoh8v/8uiwek=
 golang.org/x/text v0.21.0 h1:zyQAAkrwaneQ066sspRyJaG9VNi/YJ1NfzcGB3hZ/qo=
 golang.org/x/text v0.21.0/go.mod h1:4IBbMaMmOPCJ8SecivzSH54+73PCFmPWxNTLm+vZkEQ=
+google.golang.org/genproto/googleapis/api v0.0.0-20250106144421-5f5ef82da422 h1:GVIKPyP/kLIyVOgOnTwFOrvQaQUzOzGMCxgFUOEmm24=
+google.golang.org/genproto/googleapis/api v0.0.0-20250106144421-5f5ef82da422/go.mod h1:b6h1vNKhxaSoEI+5jc3PJUCustfli/mRab7295pY7rw=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20250106144421-5f5ef82da422 h1:3UsHvIr4Wc2aW4brOaSCmcxh9ksica6fHEr8P1XhkYw=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20250106144421-5f5ef82da422/go.mod h1:3ENsm/5D1mzDyhpzeRi1NR784I0BcofWBoSc5QqqMK4=
+google.golang.org/grpc v1.69.2 h1:U3S9QEtbXC0bYNvRtcoklF3xGtLViumSYxWykJS+7AU=
+google.golang.org/grpc v1.69.2/go.mod h1:vyjdE6jLBI76dgpDojsFGNaHlxdjXN9ghpnd2o7JGZ4=
+google.golang.org/protobuf v1.36.2 h1:R8FeyR1/eLmkutZOM5CWghmo5itiG9z0ktFlTVLuTmU=
+google.golang.org/protobuf v1.36.2/go.mod h1:9fA7Ob0pmnwhb644+1+CVWFRbNajQ6iRojtC/QF5bRE=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=

graphql.go

@@ -38,7 +38,7 @@ func prepareQueriesAndExemptions() {
 
 	// Process allowed URLs
 	for _, u := range cfg.Server.AllowURLs {
-			allowedUrls[u] = struct{}{}
+		allowedUrls[u] = struct{}{}
 	}
 }
 
@@ -178,33 +178,33 @@ func parseGraphQLQuery(c *fiber.Ctx) *parseGraphQLQueryResult {
 
 func checkSelections(c *fiber.Ctx, selections []ast.Selection) bool {
 	for _, s := range selections {
-			switch sel := s.(type) {
+		switch sel := s.(type) {
-			case *ast.Field:
+		case *ast.Field:
-					fieldName := strings.ToLower(sel.Name.Value)
+			fieldName := strings.ToLower(sel.Name.Value)
-					if _, exists := introspectionQueries[fieldName]; exists {
+			if _, exists := introspectionQueries[fieldName]; exists {
-							if len(cfg.Security.IntrospectionAllowed) > 0 {
+				if len(cfg.Security.IntrospectionAllowed) > 0 {
-									_, allowed := introspectionAllowedQueries[fieldName]
+					_, allowed := introspectionAllowedQueries[fieldName]
-									if !allowed {
+					if !allowed {
-											return true // Block if this field isn't allowed
+						return true // Block if this field isn't allowed
-									}
-									// Even if this field is allowed, we need to check its nested selections
-							} else {
-									return true // Block if no allowlist exists
-							}
-					}
-					// Always check nested selections
-					if sel.SelectionSet != nil {
-							if checkSelections(c, sel.GetSelectionSet().Selections) {
-									return true
-							}
-					}
-			case *ast.InlineFragment:
-					if sel.SelectionSet != nil {
-							if checkSelections(c, sel.GetSelectionSet().Selections) {
-									return true
-							}
 					}
+					// Even if this field is allowed, we need to check its nested selections
+				} else {
+					return true // Block if no allowlist exists
+				}
 			}
+			// Always check nested selections
+			if sel.SelectionSet != nil {
+				if checkSelections(c, sel.GetSelectionSet().Selections) {
+					return true
+				}
+			}
+		case *ast.InlineFragment:
+			if sel.SelectionSet != nil {
+				if checkSelections(c, sel.GetSelectionSet().Selections) {
+					return true
+				}
+			}
+		}
 	}
 	return false
 }

main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"context"
 	"flag"
 	"os"
 	"strings"
@@ -13,11 +14,13 @@ import (
 	libpack_cache "github.com/lukaszraczylo/graphql-monitoring-proxy/cache"
 	libpack_config "github.com/lukaszraczylo/graphql-monitoring-proxy/config"
 	libpack_logging "github.com/lukaszraczylo/graphql-monitoring-proxy/logging"
+	libpack_tracing "github.com/lukaszraczylo/graphql-monitoring-proxy/tracing"
 )
 
 var (
-	cfg  *config
+	cfg    *config
-	once sync.Once
+	once   sync.Once
+	tracer *libpack_tracing.TracingSetup
 )
 
 // getDetailsFromEnv retrieves the value from the environment or returns the default.
@@ -102,8 +105,38 @@ func parseConfig() {
 	c.HasuraEventCleaner.Enable = getDetailsFromEnv("HASURA_EVENT_CLEANER", false)
 	c.HasuraEventCleaner.ClearOlderThan = getDetailsFromEnv("HASURA_EVENT_CLEANER_OLDER_THAN", 1)
 	c.HasuraEventCleaner.EventMetadataDb = getDetailsFromEnv("HASURA_EVENT_METADATA_DB", "")
+	// Tracing configuration
+	c.Tracing.Enable = getDetailsFromEnv("ENABLE_TRACE", false)
+	c.Tracing.Endpoint = getDetailsFromEnv("TRACE_ENDPOINT", "localhost:4317")
 	cfg = &c
 
+	// Initialize tracing if enabled
+	if cfg.Tracing.Enable {
+		if cfg.Tracing.Endpoint == "" {
+			cfg.Logger.Warning(&libpack_logging.LogMessage{
+				Message: "Tracing endpoint not configured, using default localhost:4317",
+			})
+			cfg.Tracing.Endpoint = "localhost:4317"
+		}
+
+		var err error
+		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		defer cancel()
+
+		tracer, err = libpack_tracing.NewTracing(ctx, cfg.Tracing.Endpoint)
+		if err != nil {
+			cfg.Logger.Error(&libpack_logging.LogMessage{
+				Message: "Failed to initialize tracing",
+				Pairs:   map[string]interface{}{"error": err.Error()},
+			})
+		} else {
+			cfg.Logger.Info(&libpack_logging.LogMessage{
+				Message: "Tracing initialized",
+				Pairs:   map[string]interface{}{"endpoint": cfg.Tracing.Endpoint},
+			})
+		}
+	}
+
 	// Initialize cache if enabled
 	if cfg.Cache.CacheEnable || cfg.Cache.CacheRedisEnable {
 		cacheConfig := &libpack_cache.CacheConfig{
@@ -133,6 +166,16 @@ func main() {
 	StartMonitoringServer()
 	time.Sleep(5 * time.Second)
 	StartHTTPProxy()
+
+	// Cleanup tracing on exit
+	if tracer != nil {
+		if err := tracer.Shutdown(context.Background()); err != nil {
+			cfg.Logger.Error(&libpack_logging.LogMessage{
+				Message: "Error shutting down tracer",
+				Pairs:   map[string]interface{}{"error": err.Error()},
+			})
+		}
+	}
 }
 
 // ifNotInTest checks if the program is not running in a test environment.

proxy.go

@@ -3,17 +3,21 @@ package main
 import (
 	"bytes"
 	"compress/gzip"
+	"context"
 	"crypto/tls"
 	"fmt"
 	"io"
 	"net/url"
 	"time"
 
+	"go.opentelemetry.io/otel/trace"
+
 	"github.com/avast/retry-go/v4"
 	"github.com/gofiber/fiber/v2"
 	"github.com/gofiber/fiber/v2/middleware/proxy"
 	libpack_logger "github.com/lukaszraczylo/graphql-monitoring-proxy/logging"
 	libpack_monitoring "github.com/lukaszraczylo/graphql-monitoring-proxy/monitoring"
+	libpack_tracing "github.com/lukaszraczylo/graphql-monitoring-proxy/tracing"
 	"github.com/valyala/fasthttp"
 )
 
@@ -36,6 +40,30 @@ func createFasthttpClient(timeout int) *fasthttp.Client {
 
 // proxyTheRequest handles the request proxying logic.
 func proxyTheRequest(c *fiber.Ctx, currentEndpoint string) error {
+	var span trace.Span
+	ctx := context.Background()
+
+	if cfg.Tracing.Enable && tracer != nil {
+		// Extract trace information from header
+		if traceHeader := c.Get("X-Trace-Span"); traceHeader != "" {
+			spanInfo, err := libpack_tracing.ParseTraceHeader(traceHeader)
+			if err != nil {
+				cfg.Logger.Warning(&libpack_logger.LogMessage{
+					Message: "Failed to parse trace header",
+					Pairs:   map[string]interface{}{"error": err.Error()},
+				})
+			} else {
+				if spanCtx, err := tracer.ExtractSpanContext(spanInfo); err == nil {
+					ctx = trace.ContextWithSpanContext(ctx, spanCtx)
+				}
+			}
+		}
+
+		// Start a new span
+		span, ctx = tracer.StartSpan(ctx, "proxy_request")
+		defer span.End()
+	}
+
 	if !checkAllowedURLs(c) {
 		cfg.Logger.Error(&libpack_logger.LogMessage{
 			Message: "Request blocked",

server.go

@@ -162,7 +162,7 @@ func processGraphQLRequest(c *fiber.Ctx) error {
 		}
 	}
 
-	wasCached := false
+	wasCached := false //nolint:ineffassign
 
 	if parsedResult.cacheRefresh {
 		cfg.Logger.Debug(&libpack_logger.LogMessage{

struct_config.go

@@ -12,8 +12,12 @@ type config struct {
 	Logger     *libpack_logging.Logger
 	LogLevel   string
 	Monitoring *libpack_monitoring.MetricsSetup
-	Api        struct{ BannedUsersFile string }
+	Tracing    struct {
-	Client     struct {
+		Enable   bool
+		Endpoint string
+	}
+	Api    struct{ BannedUsersFile string }
+	Client struct {
 		GQLClient        *graphql.BaseClient
 		FastProxyClient  *fasthttp.Client
 		JWTUserClaimPath string

tracing/tracing.go

@@ -0,0 +1,113 @@
+package tracing
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"
+	"go.opentelemetry.io/otel/propagation"
+	"go.opentelemetry.io/otel/sdk/resource"
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
+	semconv "go.opentelemetry.io/otel/semconv/v1.21.0"
+	"go.opentelemetry.io/otel/trace"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/insecure"
+)
+
+type TracingSetup struct {
+	tracerProvider *sdktrace.TracerProvider
+	tracer         trace.Tracer
+}
+
+type TraceSpanInfo struct {
+	TraceParent string `json:"traceparent"`
+}
+
+// NewTracing creates a new tracing setup with OTLP exporter
+func NewTracing(ctx context.Context, endpoint string) (*TracingSetup, error) {
+	if ctx == nil {
+		return nil, fmt.Errorf("context cannot be nil")
+	}
+	if endpoint == "" {
+		return nil, fmt.Errorf("endpoint cannot be empty")
+	}
+
+	conn, err := grpc.DialContext(ctx, endpoint,
+		grpc.WithTransportCredentials(insecure.NewCredentials()),
+		grpc.WithBlock(),
+		grpc.WithReturnConnectionError(),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create gRPC connection to collector: %w", err)
+	}
+
+	exporter, err := otlptracegrpc.New(ctx, otlptracegrpc.WithGRPCConn(conn))
+	if err != nil {
+		return nil, fmt.Errorf("failed to create trace exporter: %w", err)
+	}
+
+	res, err := resource.New(ctx,
+		resource.WithAttributes(
+			semconv.ServiceName("graphql-monitoring-proxy"),
+		),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create resource: %w", err)
+	}
+
+	tracerProvider := sdktrace.NewTracerProvider(
+		sdktrace.WithBatcher(exporter),
+		sdktrace.WithResource(res),
+	)
+	otel.SetTracerProvider(tracerProvider)
+	otel.SetTextMapPropagator(propagation.TraceContext{})
+
+	tracer := tracerProvider.Tracer("graphql-monitoring-proxy")
+
+	return &TracingSetup{
+		tracerProvider: tracerProvider,
+		tracer:         tracer,
+	}, nil
+}
+
+// ExtractSpanContext extracts span context from TraceSpanInfo
+func (ts *TracingSetup) ExtractSpanContext(spanInfo *TraceSpanInfo) (trace.SpanContext, error) {
+	carrier := propagation.MapCarrier{
+		"traceparent": spanInfo.TraceParent,
+	}
+	ctx := context.Background()
+	ctx = otel.GetTextMapPropagator().Extract(ctx, carrier)
+	spanCtx := trace.SpanContextFromContext(ctx)
+	if !spanCtx.IsValid() {
+		return trace.SpanContext{}, fmt.Errorf("invalid span context")
+	}
+	return spanCtx, nil
+}
+
+// ParseTraceHeader parses X-Trace-Span header content
+func ParseTraceHeader(headerContent string) (*TraceSpanInfo, error) {
+	var spanInfo TraceSpanInfo
+	if err := json.Unmarshal([]byte(headerContent), &spanInfo); err != nil {
+		return nil, fmt.Errorf("failed to parse trace header: %w", err)
+	}
+	return &spanInfo, nil
+}
+
+// Shutdown cleanly shuts down the tracer provider
+func (ts *TracingSetup) Shutdown(ctx context.Context) error {
+	if ts.tracerProvider == nil {
+		return nil
+	}
+	return ts.tracerProvider.Shutdown(ctx)
+}
+
+// StartSpan starts a new span with the given name and parent context
+func (ts *TracingSetup) StartSpan(ctx context.Context, name string) (trace.Span, context.Context) {
+	if ts.tracer == nil {
+		return trace.SpanFromContext(ctx), ctx
+	}
+	ctx, span := ts.tracer.Start(ctx, name)
+	return span, ctx
+}

tracing/tracing_test.go

@@ -0,0 +1,102 @@
+package tracing
+
+import (
+	"context"
+	"encoding/json"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"go.opentelemetry.io/otel/trace"
+)
+
+func TestParseTraceHeader(t *testing.T) {
+	tests := []struct {
+		name    string
+		header  string
+		want    *TraceSpanInfo
+		wantErr bool
+	}{
+		{
+			name:   "valid trace header",
+			header: `{"traceparent": "00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-01"}`,
+			want: &TraceSpanInfo{
+				TraceParent: "00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-01",
+			},
+			wantErr: false,
+		},
+		{
+			name:    "invalid json",
+			header:  `{"traceparent": invalid}`,
+			want:    nil,
+			wantErr: true,
+		},
+		{
+			name:    "empty header",
+			header:  "",
+			want:    nil,
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := ParseTraceHeader(tt.header)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("ParseTraceHeader() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !tt.wantErr {
+				gotJSON, _ := json.Marshal(got)
+				wantJSON, _ := json.Marshal(tt.want)
+				if string(gotJSON) != string(wantJSON) {
+					t.Errorf("ParseTraceHeader() = %v, want %v", string(gotJSON), string(wantJSON))
+				}
+			}
+		})
+	}
+}
+
+func TestNewTracing(t *testing.T) {
+	// Skip actual connection tests since they require a running collector
+	t.Run("empty endpoint", func(t *testing.T) {
+		ctx := context.Background()
+		_, err := NewTracing(ctx, "")
+		assert.Error(t, err, "Expected error for empty endpoint")
+		assert.Contains(t, err.Error(), "endpoint cannot be empty")
+	})
+
+	t.Run("nil context", func(t *testing.T) {
+		_, err := NewTracing(nil, "localhost:4317")
+		assert.Error(t, err, "Expected error for nil context")
+		assert.Contains(t, err.Error(), "context cannot be nil")
+	})
+}
+
+func TestTracingSetup_ExtractSpanContext(t *testing.T) {
+	ts := &TracingSetup{}
+	spanInfo := &TraceSpanInfo{
+		TraceParent: "invalid-traceparent",
+	}
+
+	_, err := ts.ExtractSpanContext(spanInfo)
+	assert.Error(t, err, "Expected error for invalid traceparent")
+	assert.Contains(t, err.Error(), "invalid span context")
+}
+
+func TestTracingSetup_StartSpan(t *testing.T) {
+	ts := &TracingSetup{}
+	ctx := context.Background()
+
+	span, newCtx := ts.StartSpan(ctx, "test-span")
+	assert.NotNil(t, span, "Expected non-nil span even when tracer is nil")
+	assert.NotNil(t, newCtx, "Expected non-nil context")
+	assert.Equal(t, trace.SpanFromContext(ctx), span, "Expected span from context when tracer is nil")
+}
+
+func TestTracingSetup_Shutdown(t *testing.T) {
+	ts := &TracingSetup{}
+	ctx := context.Background()
+
+	err := ts.Shutdown(ctx)
+	assert.NoError(t, err, "Expected no error when shutting down nil tracer provider")
+}