fix: replace logrus with slog

[ricochet]

The golang's blog article introducing slog calls out logrus directly as tooling it aims to replace with a solution in the standard language library.

This change replaces logrus with slog and adjusts some of the log outputs to use structured logs.

Closes: #780

[Copilot]

Pull Request Overview

This PR replaces the logrus logging library with Go's standard library slog for structured logging. The change modernizes the logging approach by adopting the recommended standard library solution that aims to replace third-party logging libraries like logrus.

• Replace logrus imports with standard library slog across the codebase
• Convert logging calls to use structured logging with key-value pairs
• Update logger initialization and configuration to use slog handlers

Reviewed Changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated 2 comments.

File	Description
go.mod	Remove logrus dependency from module requirements
pkg/log/io.go	Update IOLogger to use slog.Logger and convert log messages to structured format
pkg/log/io_test.go	Update test setup to use slog with custom time removal function
internal/ghmcp/server.go	Replace logrus with slog in server initialization and logging calls

[Copilot]

The stdLogger is created with os.Stderr as output, but when a log file is configured, the slog logger uses the file while stdLogger still writes to stderr. This creates inconsistent logging destinations. Consider using the same output destination for both loggers.

Note: See the diff below for a potential fix:

@@ -206,18 +206,21 @@
 	stdioServer := server.NewStdioServer(ghServer)
 
 	var slogHandler slog.Handler
+	var logOutput io.Writer
 	if cfg.LogFilePath != "" {
 		file, err := os.OpenFile(cfg.LogFilePath, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0600)
 		if err != nil {
 			return fmt.Errorf("failed to open log file: %w", err)
 		}
+		logOutput = file
 		slogHandler = slog.NewTextHandler(file, &slog.HandlerOptions{Level: slog.LevelDebug})
 	} else {
+		logOutput = os.Stderr
 		slogHandler = slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelInfo})
 	}
 	logger := slog.New(slogHandler)
 	logger.Info("starting server", "version", cfg.Version, "host", cfg.Host, "dynamicToolsets", cfg.DynamicToolsets, "readOnly", cfg.ReadOnly)
-	stdLogger := log.New(os.Stderr, stdioServerLogPrefix, 0)
+	stdLogger := log.New(logOutput, stdioServerLogPrefix, 0)
 	stdioServer.SetErrorLogger(stdLogger)
 
 	if cfg.ExportTranslations {

[ricochet]

Please double-check the io.Writer to stdLogger as file logOutput is desired. I updated the commit to follow the GH recommendation

[mattdholloway]

@ricochet Could you run script/licenses to update the licenses on this branch? Otherwise I'm a fan of this change, and reducing our dependencies.

[mattdholloway]

Looks good!