github.com/sirupsen/logrus v1.6.0: AddHook

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify github.com/sirupsen/logrus.AddHook in pkg:golang/github.com/sirupsen/logrus@v1.6.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/sirupsen/logrus@v1.6.0
Demonstrate these symbols/APIs:
  - github.com/sirupsen/logrus.AddHook

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:76a22f948c63af1cf19fab2366da796dbbb4d71462b049954c77a7f76092337e","contract":["logrus.AddHook registers a hook on the standard logger that executes Fire for matching log levels and injects fields into entry.Data","logrus.AddHook does not invoke Fire when the event log level is not included in hook.Levels","logrus.AddHook supports multiple registered hooks executing sequentially for matching log levels"],"goal":"verify github.com/sirupsen/logrus.AddHook in pkg:golang/github.com/sirupsen/logrus@v1.6.0","kind":"HOW","packages":["pkg:golang/github.com/sirupsen/logrus@v1.6.0"],"schemaVersion":1,"symbols":["github.com/sirupsen/logrus.AddHook"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/github.com/sirupsen/logrus@v1.6.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/sirupsen/logrus@v1.6.0","symbols":["github.com/sirupsen/logrus.AddHook"],"verifierAdapter":"golang@1"}

module example.com/logrus-hook-sample

go 1.26.6

require github.com/sirupsen/logrus v1.6.0

require (
	github.com/konsorten/go-windows-terminal-sequences v1.0.3 // indirect
	golang.org/x/sys v0.0.0-20190422165155-953cdadca894 // indirect
)

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/konsorten/go-windows-terminal-sequences v1.0.3 h1:CE8S1cTafDpPvMhIxNJKvHsGVBgn1xWYf1NbHQhywc8=
github.com/konsorten/go-windows-terminal-sequences v1.0.3/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
github.com/sirupsen/logrus v1.6.0 h1:UBcNElsrwanuuMsnGSlYmtmgbb23qDR5dG+6X6Oo89I=
github.com/sirupsen/logrus v1.6.0/go.mod h1:7uNnSEd1DgxDLC74fIahvMZmmYsHGZGEOFrfsX/uA88=
github.com/stretchr/testify v1.2.2 h1:bSDNvY7ZPG5RlJ8otE/7V6gMiyenm9RtJ7IUVIAoJ1w=
github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
golang.org/x/sys v0.0.0-20190422165155-953cdadca894 h1:Cz4ceDQGXuKRnVBDTS23GTn/pU5OE2C0WrNTOYK1Uuc=
golang.org/x/sys v0.0.0-20190422165155-953cdadca894/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=

package main

import (
	"fmt"
	"io"

	"github.com/sirupsen/logrus"
)

// AppMetadataHook injects default service metadata into log entries.
type AppMetadataHook struct {
	appName string
}

func (h *AppMetadataHook) Levels() []logrus.Level {
	return []logrus.Level{
		logrus.InfoLevel,
		logrus.WarnLevel,
		logrus.ErrorLevel,
	}
}

func (h *AppMetadataHook) Fire(entry *logrus.Entry) error {
	entry.Data["app"] = h.appName
	return nil
}

func main() {
	logrus.SetOutput(io.Discard)
	hook := &AppMetadataHook{appName: "sample-service"}
	logrus.AddHook(hook)

	logrus.Info("Application initialized successfully")
	fmt.Println("Hook registered and log emitted")
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/sirupsen/logrus.AddHook in pkg:golang/github.com/sirupsen/logrus@v1.6.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/sirupsen/logrus@v1.6.0"
  ],
  "symbols": [
    "github.com/sirupsen/logrus.AddHook"
  ]
}

package main

import (
	"fmt"
	"io"
	"os"

	"github.com/sirupsen/logrus"
)

// InspectHook tracks fire count and records the last received entry.
type InspectHook struct {
	fireCount int
	lastData  logrus.Fields
	lastMsg   string
	lastLevel logrus.Level
	levels    []logrus.Level
}

func (h *InspectHook) Levels() []logrus.Level {
	return h.levels
}

func (h *InspectHook) Fire(entry *logrus.Entry) error {
	h.fireCount++
	h.lastMsg = entry.Message
	h.lastLevel = entry.Level
	h.lastData = make(logrus.Fields)
	for k, v := range entry.Data {
		h.lastData[k] = v
	}
	entry.Data["injected_field"] = "contract_verified"
	return nil
}

// OrderTrackingHook appends an ID to a shared execution slice.
type OrderTrackingHook struct {
	id     string
	levels []logrus.Level
	order  *[]string
}

func (h *OrderTrackingHook) Levels() []logrus.Level {
	return h.levels
}

func (h *OrderTrackingHook) Fire(entry *logrus.Entry) error {
	*h.order = append(*h.order, h.id)
	return nil
}

func main() {
	logrus.SetOutput(io.Discard)

	// Assertion 1: logrus.AddHook registers a hook on the standard logger that executes Fire for matching log levels and injects fields into entry.Data
	hook1 := &InspectHook{
		levels: []logrus.Level{logrus.InfoLevel, logrus.WarnLevel},
	}
	logrus.AddHook(hook1)

	logrus.WithField("initial_key", "initial_val").Info("test assertion 1 message")

	if hook1.fireCount != 1 {
		fmt.Fprintf(os.Stderr, "assertion 1 failed: expected fireCount=1, got %d\n", hook1.fireCount)
		os.Exit(1)
	}
	if hook1.lastMsg != "test assertion 1 message" {
		fmt.Fprintf(os.Stderr, "assertion 1 failed: expected message 'test assertion 1 message', got %q\n", hook1.lastMsg)
		os.Exit(1)
	}
	if hook1.lastLevel != logrus.InfoLevel {
		fmt.Fprintf(os.Stderr, "assertion 1 failed: expected InfoLevel, got %v\n", hook1.lastLevel)
		os.Exit(1)
	}
	if val, ok := hook1.lastData["initial_key"]; !ok || val != "initial_val" {
		fmt.Fprintf(os.Stderr, "assertion 1 failed: missing or incorrect initial_key in lastData: %v\n", hook1.lastData)
		os.Exit(1)
	}

	// Assertion 2: logrus.AddHook does not invoke Fire when the event log level is not included in hook.Levels
	hook2 := &InspectHook{
		levels: []logrus.Level{logrus.ErrorLevel},
	}
	logrus.AddHook(hook2)

	logrus.Info("this is an info message that hook2 should ignore")

	if hook2.fireCount != 0 {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: expected fireCount=0 for non-matching level, got %d\n", hook2.fireCount)
		os.Exit(1)
	}

	// Assertion 3: logrus.AddHook supports multiple registered hooks executing sequentially for matching log levels
	var execOrder []string
	orderHookA := &OrderTrackingHook{
		id:     "hookA",
		levels: []logrus.Level{logrus.WarnLevel},
		order:  &execOrder,
	}
	orderHookB := &OrderTrackingHook{
		id:     "hookB",
		levels: []logrus.Level{logrus.WarnLevel},
		order:  &execOrder,
	}
	logrus.AddHook(orderHookA)
	logrus.AddHook(orderHookB)

	logrus.Warn("warning message to trigger ordered hooks")

	if len(execOrder) != 2 || execOrder[0] != "hookA" || execOrder[1] != "hookB" {
		fmt.Fprintf(os.Stderr, "assertion 3 failed: expected execution order [hookA, hookB], got %v\n", execOrder)
		os.Exit(1)
	}

	fmt.Println("PASS: logrus.AddHook contract verified")
}