logger

Logger

Standardizing logging for GO applications

Uses slog from the standard library to have consistent structured logging across applications.

The logger should be configured and set up in the main function of the application and accessed through the slog package.

Configuration

The logger will take the following environment variables to configure the logger.

Usage

import (
    "errors"
    "log/slog"

    "github.com/jesse0michael/pkg/logger"
)

func main() {
    logger.SetLog()
    ctx := context.Background()

    // ...


    slog.With("key", "value").InfoContext(ctx, "writing logs")
    // {"time":"2023-08-21T09:15:18.111628-07:00","level":"INFO","msg":"writing logs","host":"local","environment":"test","key":"value"}

    slog.With("error", errors.New("test-error")).ErrorContext(ctx, "writing errors") 
    // {"time":"2023-08-21T09:15:18.111716-07:00","level":"ERROR","msg":"writing errors","host":"local","environment":"test","error":"test-error"}
}

Context Handler

The default logger is configured with a ContextHandler that allow you to set attributes in the GO context that will be logged with every log message.

import (
    "errors"
    "log/slog"

    "github.com/jesse0michael/pkg/logger"
)

func main() {
    _ = logger.NewLogger()
    ctx := context.Background()
    ctx = logger.AddAttrs(ctx, slog.String("accountID", "12345"))

    // ...

    slog.InfoContext(ctx, "writing logs")
    // {"time":"2023-08-21T09:15:18.111628-07:00","level":"INFO","msg":"writing logs","host":"local","environment":"test","accountID":"12345"}

    slog.With("error", errors.New("test-error")).ErrorContext(ctx, "writing errors") 
    // {"time":"2023-08-21T09:15:18.111628-07:00","level":"ERROR","msg":"writing errors","host":"local","environment":"test","error":"test-error","accountID":"12345"}
}

Error Warn Handler

The logger can be configured with an ErrorWarnHandler that will log errors as warnings if an error attribute matches a specified function.

import (
    "context"
    "errors"
    "log/slog"

    "github.com/jesse0michael/pkg/logger"
)

func main() {
    warnCheck := func(err error) bool { return err == context.Canceled }
    logger.NewLogger()
    logger.SetErrorWarnHandler(warnCheck)
    ctx := context.Background()

    // ...

    slog.With("error", context.Canceled).ErrorContext(ctx, "writing errors") 
    // {"time":"2023-08-21T09:15:18.111628-07:00","level":"WARN","msg":"writing errors","host":"local","environment":"test","error":"context canceled"}
}