akvorado/common/reporter/logger/root.go

// SPDX-FileCopyrightText: 2022 Free Mobile
// SPDX-License-Identifier: AGPL-3.0-only

// Package logger handles logging for akvorado.
//
// This is a thin wrapper around zerolog. It is currently not
// configurable as we don't need anything fancy yet for configuration.
//
// It also brings some conventions like the presence of "module" in
// each context to be able to filter logs more easily. However, this
// convention is not really enforced. Once you have a root logger,
// create sublogger with New and provide a new value for "module".
package logger

import (
	"strings"

	"github.com/rs/zerolog"
	"github.com/rs/zerolog/log"

	"akvorado/common/reporter/stack"
)

// Logger is a logger instance. It is compatible with the interface
// from zerolog by design.
type Logger struct {
	zerolog.Logger
}

// New creates a new logger
func New(_ Configuration) (Logger, error) {
	// Initialize the logger
	logger := log.Logger.Hook(contextHook{})
	return Logger{logger}, nil
}

type contextHook struct{}

// Run adds more context to an event, including "module" and "caller".
func (h contextHook) Run(e *zerolog.Event, _ zerolog.Level, _ string) {
	callStack := stack.Callers()
	callStack = callStack[3:] // Trial and error, there is a test to check it works.

	// We want to get the first caller that is in our module and isn't preferably in logs.go.
	var candidateInfo *stack.CallInfo
	for _, call := range callStack {
		info := call.Info()
		if !strings.HasPrefix(info.FunctionName(), stack.ModuleName) {
			continue
		}
		candidateInfo = info
		if strings.HasSuffix(info.FileName(), "/logs.go") {
			continue
		}
		break
	}
	if candidateInfo != nil {
		e.Str("caller", candidateInfo.SourceFile())
		e.Str("module", strings.SplitN(candidateInfo.FunctionName(), ".", 2)[0])
	}
}