merging commit as one

.github/CODEOWNERS

@@ -0,0 +1,2 @@
+*                       @razorpay/go_maintainers
+/opentelemetry/         @razorpay/spine-edge

.github/workflows/tests.yml

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+name: Run Tests
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+on:
+  push:
+    branches:
+      - 'master'
+  pull_request:
+
+jobs:
+  test:
+    runs-on: [ self-hosted, non-api ]
+    strategy:
+      max-parallel: 4
+      matrix:
+        go-version: ["1.23"]
+
+    name: Run Tests
+    steps:
+      - name: checkout
+        uses: actions/checkout@v2
+
+      - name: setup golang
+        uses: actions/setup-go@v5
+        with:
+          go-version: '${{ matrix.go-version }}'
+
+      - run: sh ./run_tests.sh
+        env:
+          GIT_TOKEN: ${{ secrets.GIT_TOKEN }}
+          GOPRIVATE: github.com/razorpay/*

.gitignore

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+# vendor folder
+vendor/*
+
+# idea folder created by JetBrains
+.idea/
+
+# vscode folder
+.vscode/*
+
+# tmp folder
+tmp/*
+
+# Desktop Services Store
+.DS_Store
+
+**/vendor

README.md

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+# golib

opentelemetry/.golangci.yml

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+# Reference file : https://github.com/golangci/golangci-lint/blob/master/.golangci.reference.yml
+run:
+  timeout: 10m
+  paths:
+    exclude:
+      - tests/**
+linters-settings:
+  tagalign:
+    sort: false
+
+linters:
+  enable-all: true
+  disable:
+    - deadcode # deprecated
+    - exhaustivestruct # deprecated
+    - golint # deprecated
+    - ifshort # deprecated
+    - interfacer # deprecated
+    - maligned # deprecated
+    - nosnakecase # deprecated
+    - scopelint # deprecated
+    - scopelint # deprecated
+    - structcheck # deprecated
+    - varcheck # deprecated
+    - sqlclosecheck # not relevant yet (SQL)
+    - rowserrcheck # not relevant yet (SQL)
+    - execinquery # not relevant yet (SQL)
+    - cyclop # duplicate of gocyclo
+    - lll # Not relevant
+    - gocyclo # FIXME must be fixed
+    - gocognit # Too strict
+    - nestif # Too many false-positive.
+    - prealloc # Too many false-positive.
+    - makezero # Not relevant
+    - dupl # Too strict
+    - gosec # Too strict
+    - gochecknoinits
+    - gochecknoglobals
+    - wsl # Too strict
+    - nlreturn # Not relevant
+    - gomnd # Too strict
+    - stylecheck # skip because report issues related to some generated files.
+    - testpackage # Too strict
+    - tparallel # Not relevant
+    - paralleltest # Not relevant
+    - exhaustive # Not relevant
+    - exhaustruct # Not relevant
+    - goerr113 # Too strict
+    - wrapcheck # Too strict
+    - noctx # Too strict
+    - bodyclose # too many false-positive
+    - forcetypeassert # Too strict
+    - tagliatelle # Too strict
+    - varnamelen # Not relevant
+    - nilnil # Not relevant
+    - ireturn # Not relevant
+    - contextcheck # too many false-positive
+    - containedctx # too many false-positive
+    - maintidx # kind of duplicate of gocyclo
+    - nonamedreturns # Too strict
+    - gosmopolitan  # not relevant
+    - depguard # Not relevant for now as we don't have a list of blacklisted dependencies
+    - gci # not relevant as go imports is already used
+    - godot # not relevant as it only checks if the comment is ended in period or not.
+    - gofumpt # not relevant as we use goimports
+    - thelper # test case helper linter, not relevant
+    - inamedparam # Named interface params
+
+issues:
+  # Excluding configuration per-path, per-linter, per-text and per-source
+  exclude-rules:
+    # Exclude some linters from running on tests files.
+    - path: '(.+)_test.go'
+      linters:
+        - errcheck
+        - funlen
+        - usestdlibvars
+        - thelper
+        - errchkjson
+        - goconst
+        - testifylint
+    - path: 'tests'
+      linters:
+        - thelper
+        - testifylint
+

opentelemetry/Makefile

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+.PHONY: build integration-test unit-test lint imports obs-stack-up obs-stack-down run-example run-test
+
+build:
+	go build -v ./...
+
+integration-test:
+	go test -race -v ./tests --tags=integration
+
+unit-test:
+	go test -race -v ./... -coverprofile=unit-test.cov -covermode=atomic
+
+lint:
+	@golangci-lint run --config=.golangci.yml
+
+imports:
+	goimports -w .
+
+obs-stack-up:
+	docker-compose -f ./tests/testdata/docker-compose.yaml up -d
+
+obs-stack-down:
+	docker-compose -f ./tests/testdata/docker-compose.yaml down
+
+run-example:
+	make obs-stack-up
+	cd ./example && go build -v ./... && ./example
+
+run-test:
+	make unit-test
+	make integration-test
+

opentelemetry/README.md

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+# Opentelemetry
+Package opentelemetry provides telemetry instrumentation support for applications
+using Opentelemetry specification. This package owns the responsibility of
+creating and destroying telemetry providers which sends data to the external
+components via exporters provided in the configuration.
+
+## Features
+1. Instrumentation support for Tracing
+2. Instrumentation support for Metrics
+
+## Usage Examples
+
+### Fetch the package as a dependency
+```go
+    go get -u github.com/razorpay/goutils/opentelemetry
+```
+### Parse and generate the [opentelemetry configuration] (opentelemetry/config/config.go)
+The client is responsible for generating opentelemetry configuration. Client can have an example opentelemetry configuration
+block like below in its configuration file:
+```
+{
+    "service_name": "local_service",
+    "exporters": [
+        {
+            "name": "local_prometheus",
+            "kind": "prometheus",
+            "config": {
+                "port": 9092,
+                "process_metrics": true,
+                "go_metrics": true
+            }
+        },
+        {
+            "name": "local_tempo",
+            "kind": "opentelemetry",
+            "config": {
+                "host": "localhost",
+                "port": 4317,
+            }
+        },
+        {
+            "name": "local_jaeger",
+            "kind": "opentelemetry",
+            "config": {
+                "host": "localhost"
+                "port": 14268,
+            }
+        }
+    ],
+    "metrics": {
+      "exporters": ["local_prometheus"]
+    },
+    "traces": {
+      "exporters": ["local_tempo", "local_jaeger"],
+      "sample_rate": 1
+    }
+}
+```
+
+### Initialise the instrumentation providers
+After generating the above configuration for opentelemetry, initialise the instrumentation providers like below:
+```go
+    err := opentelemetry.Register(context, opentelemetry)
+```
+
+### Instrument application for Tracing
+```go
+      tracer := otel.Tracer("test")
+      commonAttrs := []attribute.KeyValue{
+        attribute.String("attrA", "A"),
+        attribute.String("attrB", "B"),
+        attribute.String("attrC", "C"),
+      }
+      ctx, span := tracer.Start(
+        ctx,
+        "test-example",
+        trace.WithAttributes(commonAttrs...))
+
+	  // some operation
+
+      span.End()
+```
+### Instrument application for Metrics
+```go
+        meter := otel.Meter("test-example")
+	opt := api.WithAttributes(
+		attribute.Key("attrA").String("A"),
+		attribute.Key("attrB").String("B"),
+	)
+	counter, err := meter.Float64Counter("foo")
+	counter.Add(context, 5, opt)
+	histogram, err := meter.Float64Histogram(
+		"baz",
+		api.WithDescription("a histogram with custom buckets and rename"),
+		api.WithExplicitBucketBoundaries(64, 128, 256, 512, 1024, 2048, 4096),
+	)
+	histogram.Record(context, 136, opt)
+```
+
+For more details, refer [opentelemetry/example/main.go] (example instrumentation file)
+
+### Viewing example telemetry data
+Run ``` make run-example  ``` to run a sample instrumentation 'test-service' application and to set up Prometheus, Otel-collector and Jaeger which will collect metrics and tracing data
+of the application.
+1. To view traces, use jaeger endpoint ``` localhost:16686  ```.
+2. To view metrics, use prometheus endpoint ``` localhost:9090  ```.
+3. Run ``` make obs-stack-down ``` to bring down the observability stack.
+
+### Viewing telemetry data for any application
+Run ``` make obs-stack  ``` to setup Prometheus, Otel-collector and Jaeger which will collect metrics and tracing data
+of the application which are exporting data to them.
+1. To view traces, use jaeger endpoint ``` localhost:16686  ```.
+2. To view metrics, use prometheus endpoint ``` localhost:9090  ```.
+3. Run ``` make obs-stack-down ``` to bring down the observability stack.
+
+## TODOs
+- Support for push based configuration for exporting metrics
+- Allow different formats for the propagation of the trace (the `TextMapPropagator`)
+- Support for exporting Metrics and Logging using Opentelemetry Exporter
+

opentelemetry/config/config.go

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+package config
+
+import (
+	"errors"
+)
+
+var ErrNoExporter = errors.New("no exporters declared")
+var ErrTelemetryConfigMissing = errors.New("config for telemetry instance is not provided")
+
+// Config is the root configuration for the OTEL observability stack
+type Config struct {
+	ServiceName string `mapstructure:"service_name" json:"service_name"`
+	Exporters   []Exporter
+	Metrics     *MetricsConfig
+	Trace       *TraceConfig
+}
+
+type ExporterKind string
+
+// Exporter has the information to configure an exporter
+// instance.
+//
+// The Kind is the name of the kind of exporter we want:
+// OTEL, Prometheus, ...
+//
+// The Config is the configuration for this provider
+type Exporter struct {
+	Name   string
+	Kind   ExporterKind
+	Config map[string]interface{}
+}
+
+type MetricsConfig struct {
+	Exporters []string
+}
+
+type TraceConfig struct {
+	Exporters  []string
+	SampleRate float64 `mapstructure:"sample_rate" json:"sample_rate"`
+}
+
+func Validate(cfg *Config) error {
+	if cfg.Exporters == nil || len(cfg.Exporters) == 0 {
+		return ErrNoExporter
+	}
+	if cfg.Metrics == nil && cfg.Trace == nil {
+		return ErrTelemetryConfigMissing
+	}
+	return nil
+}

opentelemetry/config/util.go

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+package config
+
+import (
+	"encoding/json"
+)
+
+func Parse(configInString map[string]interface{}, cfgStructPointer interface{}) error {
+	if configInString == nil {
+		return nil
+	}
+	b, err := json.Marshal(configInString)
+	if err != nil {
+		return err
+	}
+	err = json.Unmarshal(b, cfgStructPointer)
+	if err != nil {
+		return err
+	}
+	return nil
+}