gcplog

README

gcplog

This package contains slog handler that can be used to log to stdout in a format that is compatible with Google Cloud Logging.

NewAutoHandler also falls back to console logging if the environment is not GCP.

Example

package main

import (
	"fmt"
	"log/slog"
	"os"

	"github.com/mycujoo/go-stdlib/pkg/gcplog"
)

func main() {
    h := gcplog.NewAutoHandler(os.Stderr, &gcplog.HandlerOptions{
        AddSource:      true,
        ServiceName:    "some-service",
        ReportErrors:   true,
    })
    
    err := fmt.Errorf("storage.Get: %w", os.ErrNotExist)
    
    logger := slog.New(h)
    logger.Error("operation failed", gcplog.Error(err))
}

Service name can be set through options or from environment variable GCPLOG_SERVICE_NAME. Fallback to OTEL_SERVICE_NAME is supported.

To automatically set your service version during build you can use following command:

go build -ldflags "-X github.com/mycujoo/go-stdlib/pkg/gcplog.serviceVersion=$(git rev-parse HEAD)" -o ./bin/server ./cmd/server

Alternatively you can set GCPLOG_SERVICE_VERSION environment variable.

It is based on slogdriver package, but has some changes:

1. Integrated with open telemetry directly.
2. Trace context is optional.
3. Labels removed.
4. Added service context.
5. Support for cloud error reporting.

Documentation

Index

• func Error(err error) slog.Attr
• func NewAutoHandler(w io.Writer, opts *HandlerOptions) slog.Handler
• func NewReportContext(pc uintptr) slog.Attr
• type Handler
  • func NewHandler(w io.Writer, opts *HandlerOptions) *Handler
  • func (h *Handler) Enabled(_ context.Context, level slog.Level) bool
  • func (h *Handler) Handle(ctx context.Context, r slog.Record) error
  • func (h *Handler) WithAttrs(as []slog.Attr) slog.Handler
  • func (h *Handler) WithGroup(name string) slog.Handler
• type HandlerOptions

Examples

• NewAutoHandler

Functions

func Error

func Error(err error) slog.Attr

Error wraps an error in a slog.Attr with a standard key.

func NewAutoHandler

func NewAutoHandler(w io.Writer, opts *HandlerOptions) slog.Handler

NewAutoHandler returns slog.Handler that writes to w using GCP structured logging format. It automatically detects GCP project ID. If the program is not running on GCE, it returns console handler.

Example

package main

import (
	"fmt"
	"log/slog"
	"os"

	"github.com/mycujoo/go-stdlib/pkg/gcplog"
)

func main() {
	h := gcplog.NewAutoHandler(os.Stderr, &gcplog.HandlerOptions{
		AddSource:    true,
		ServiceName:  "some-service",
		ReportErrors: true,
	})

	err := fmt.Errorf("storage.Get: %w", os.ErrNotExist)

	logger := slog.New(h)
	logger.Error("operation failed", gcplog.Error(err))
}

func NewReportContext

func NewReportContext(pc uintptr) slog.Attr

NewReportContext creates a new report context. see: https://cloud.google.com/error-reporting/docs/formatting-error-messages

Types

type Handler

type Handler struct {
	// contains filtered or unexported fields
}

func NewHandler

func NewHandler(w io.Writer, opts *HandlerOptions) *Handler

NewHandler returns slog.Handler that writes to w using GCP structured logging format.

func (*Handler) Enabled

func (h *Handler) Enabled(_ context.Context, level slog.Level) bool

func (*Handler) Handle

func (h *Handler) Handle(ctx context.Context, r slog.Record) error

func (*Handler) WithAttrs

func (h *Handler) WithAttrs(as []slog.Attr) slog.Handler

func (*Handler) WithGroup

func (h *Handler) WithGroup(name string) slog.Handler

type HandlerOptions

type HandlerOptions struct {
	// AddSource causes the handler to compute the source code position
	// of the log statement and add a SourceKey attribute to the output.
	AddSource bool

	// Minimal log level to log, defaults to slog.LevelInfo
	Level slog.Leveler

	// Service name and version to add to the log
	ServiceName    string
	ServiceVersion string

	// If this is set to true, errors will be reported to GCP error reporting.
	ReportErrors bool

	// GCP project ID to use for trace context
	GCPProjectID string
}