Comparing v0.56.0...v0.57.0 · prometheus/common (original) (raw)

Commits on Aug 28, 2024

1. feat: new promslog and promslog/flag packages to wrap log/slog
   Prereq for prometheus/prometheus#14355
   This adds a new promslog package to create an opinionated slog logger
   for use within the prometheus ecosystem. By default, logs are written at
   info level and formatted to add a kv pair for the source caller. If
   backwards compatibility for the literal output format of the logging is
   required, logs can be styled in a format that is similar to how the
   promlog package formatted it's go-kit/log output [1]. The promslog
   package also makes use of an slog.LevelVar to dynamically adjust the
   level of an existing logger. Similar to the old promlog package, we
   provide means to log in logfmt and json output formats.
   Creating a logger is similar to the old promlog package -- optionally
   populate a Config struct, and then call New() with the config.
   In order to dynamically adjust the logger's level, retain the Config
   struct as it's own variable to access the AllowedLevel.Set() method,
   which internally updates the AllowedLevel's slog.LevelVar to the
   desired log level. Ex:

config := &promslog.Config{} // Retain as variable if you need to dynamically adjust log level  
logger := promslog.New(config)  
config.Level.Set("debug")  
logger.Debug("your message here", "hello", "world")  

To use go-kit style log output:

config := &promslog.Config{Style: promslog.GoKitStyle} // Retain as variable if you need to dynamically adjust log level  
logger := promslog.New(config)  
config.Level.Set("debug")  
logger.Debug("your message here", "hello", "world")  

1. When using the go-kit log style, the following changes are made to the
   default slog output:

• adjusts slog default timestamp key from timestamp -> ts
• adjusts the timestamp value to use the same time format string
  ("2006-01-02T15:04:05.000Z07:00")
• adjusts slog default sourcecode key from source -> caller
• adjusts the formatting of the sourcecode values to trim paths with
  filepath.Base(). The formatting of the sourcecode value is similar
  to the go-kit/log usage, with the addition of the source function in
  parenthesis when debug logging is enabled.
  Signed-off-by: TJ Hoplock t.hoplock@gmail.com
  
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