sloglint

README

sloglint

A Go linter that ensures consistent code style when using log/slog.

📌 About

The log/slog API allows two different types of arguments: key-value pairs and attributes. People may have different opinions about which one is better, but nobody probably wants to mix them up because it makes the code harder to read.

slog.Info("a user has logged in", "user_id", 42, slog.String("ip_address", "192.0.2.0")) // ugh

sloglint finds such function calls and checks that all the arguments are either key-value pairs or attributes. The linter has several options, so you can adjust it to your own code style.

🚀 Features

• Forbid mixing key-value pairs and attributes within a single function call (default)
• Enforce using either key-value pairs or attributes for the entire project (optional)
• Enforce using constants instead of raw keys (optional)
• Enforce putting arguments on separate lines (optional)

📦 Install

Download a prebuilt binary from the Releases page.

📋 Usage

sloglint [flags] ./...

Key-value pairs only

The -kv-only flag causes sloglint to report any use of attributes.

slog.Info("a user has logged in", slog.Int("user_id", 42)) // sloglint: attributes should not be used

Attributes only

In contrast, the -attr-only flag causes sloglint to report any use of key-value pairs.

slog.Info("a user has logged in", "user_id", 42) // sloglint: key-value pairs should not be used

No raw keys

To prevent typos, you may want to forbid the use of raw keys altogether. The -no-raw-keys flag causes sloglint to report the use of strings as keys (including slog.Attr calls, e.g. slog.Int("user_id", 42)).

slog.Info("a user has logged in", "user_id", 42) // sloglint: raw keys should not be used

This report can be fixed by using either constants...

const UserId = "user_id"

slog.Info("a user has logged in", UserId, 42)

...or custom slog.Attr constructors.

func UserId(value int) slog.Attr { return slog.Int("user_id", value) }

slog.Info("a user has logged in", UserId(42))

💡 Such helpers can be automatically generated for you by the sloggen tool. Give it a try too!

Arguments on separate lines

To improve code readability, you may want to put arguments on separate lines, especially when using key-value pairs. The -args-on-sep-lines flag causes sloglint to report 2+ arguments on the same line.

slog.Info("a user has logged in", "user_id", 42, "ip_address", "192.0.2.0") // sloglint: arguments should be put on separate lines

This report can be fixed by reformatting the code.

slog.Info("a user has logged in",
    "user_id", 42,
    "ip_address", "192.0.2.0",
)

Documentation

Overview

Package sloglint implements the sloglint analyzer.

Index

• func New(opts *Options) *analysis.Analyzer
• type Options

Functions

func New

func New(opts *Options) *analysis.Analyzer

New creates a new sloglint analyzer.

Types

type Options

type Options struct {
	KVOnly         bool // Enforce using key-value pairs only (incompatible with AttrOnly).
	AttrOnly       bool // Enforce using attributes only (incompatible with KVOnly).
	NoRawKeys      bool // Enforce using constants instead of raw keys.
	ArgsOnSepLines bool // Enforce putting arguments on separate lines.
}

Options are options for the sloglint analyzer.