Logging2

Logging2 is a library which extends the standard Julia Logging library with additional functionality. The intent of this library is to consolidate some of the more useful "core" logging functionality from the wider Julia ecosystem, and serve as a staging area to improve the logging standard library itself.

How-To

Redirect stdout or stderr to the logging system

Use redirect_stdout or redirect_stderr to redirect all strings written to stdout or stderr to any AbstractLogger during the execution of a given do block:

logger = current_logger() # or construct one explicitly
redirect_stdout(logger) do
    println("Hi")
    run(`ls`)
end

Note that stdout and stder are global streams, so this logging choice is made globally for the whole program. Therefore, you should probably only do this at the top level of your application (certainly never in any library code which you expect to run concurrently).

The Wider Julia Logging Ecosystem

As of mid-2020, here is a list of libraries from the Julia ecosystem which relate to the standard logging infrastructure.

First off, Base exports the four logging frontend macros @debug, @info, @warn, @error and the stdlib Logging library provides a default logger backend ConsoleLogger for some basic filtering and pretty printing of log records in the terminal. It combines convenient but non-composable features into a single logger type.

Frontend

• ProgressLogging.jl provides some convenient frontend macros including @progress which makes it easy to emit log records tracking the progress of looping constructs.

Log Event routing and transformation

• LoggingExtras.jl provides generic log transformation, filtering and routing functionality. You can use this to mutate messages as they go through the chain, duplicate a stream of log records into multiple streams, discard messages based on a predicate, etc.

Sinks

• TerminalLoggers.jl is a library for advanced terminal-based pretty printing of log records, including fancy progress bars and markdown formatting.
• TensorBoardLogger.jl can log structured numeric data to TensorBoard as a backend.
• LogRoller.jl has a backend for rotating log files once they hit a size limit.
• Syslogging.jl provides a
• backend to direct logs to syslog.
• LoggingExtras.jl provides a simple FileLogger sink.

Configuration

• LogCompose.jl provides declarative logger configuration and an associated .toml file format.