ctxslog

An slog handler to pull shared information from context.Context for use with structured logging.

Installation

go get github.com/felttrip/ctxslog

Usage

• Add ctxslog into the handler chain when calling SetDefault with `slog.
• Use ctxslog.WithValue or ctxslog.WithValues to add Key Value pairs to the context to be logged
  • This operates the same way as context.Context.WithValue but with the addition of keeping track of which fields on the context should be logged.
• Use the slog.InfoContext, slog.WarnContext, or slog.ErrorContext functions providing the context that has the fields you want to log attached.

slog.SetDefault(slog.New(ctxslog.NewHandler(slog.NewJSONHandler(os.Stdout, nil))))

ctx := ctxslog.WithValue(context.Background(), "AccountID", 123456789)
ctx = ctxslog.WithValue(ctx, "email", "[email protected]")
ctx = ctxslog.WithValue(ctx, "sender", "[email protected]")

slog.InfoContext(ctx, "Info With Context")
fmt.Println()
ctx = ctxslog.WithValues(context.Background(), map[string]interface{}{
  "AccountID": 987654321,
  "email":     "[email protected]",
  "complexData": ComplexData{
    IntField:   123,
    StrField:   "DEADBEEF",
    BoolField:  true,
    SliceField: []string{"one", "two", "three"},
  },
})

slog.ErrorContext(ctx, "Error With Context")

Example Output

{"time":"2024-07-12T10:38:41.610863-06:00","level":"INFO","msg":"Info With Context","AccountID":123456789,"email":"[email protected]","sender":"[email protected]"}

{"time":"2024-07-12T10:38:41.611199-06:00","level":"ERROR","msg":"Error With Context","complexData":{"IntField":123,"StrField":"DEADBEEF","BoolField":true,"SliceField":["one","two","three"]},"AccountID":987654321,"email":"[email protected]"}