LoggingFormats.jl

This package is an aggregation of various useful format functions to use with the FormatLogger from the LoggingExtras package.

Currently, the following functors are available:

JSON: output log events as JSON
LogFmt: output log events formatted as logfmt
Truncated: truncation of log messages

`JSON`: Output log events as JSON

LoggingFormats.JSON() is a function which formats the log message and the log metadata as JSON. Example:

julia> using LoggingFormats, LoggingExtras

julia> with_logger(FormatLogger(LoggingFormats.JSON(), stderr)) do
           @info "hello, world"
           @error "something is wrong"
       end
{"level":"info","msg":"hello, world","module":"Main","file":"REPL[10]","line":2,"group":"REPL[10]","id":"Main_6972c828","kwargs":{}}
{"level":"error","msg":"something is wrong","module":"Main","file":"REPL[10]","line":3,"group":"REPL[10]","id":"Main_2289c7f9","kwargs":{}}

One can also pass recursive=true to recursively serialize the kwargs as JSON:

julia> using LoggingFormats, LoggingExtras

julia> with_logger(FormatLogger(LoggingFormats.JSON(; recursive=true), stderr)) do
                  @info "hello, world" key=Dict("hello" => true)
       end
{"level":"info","msg":"hello, world","module":"Main","file":"REPL[18]","line":2,"group":"REPL[18]","id":"Main_ffce16b5","kwargs":{"key":{"hello":true}}}

If it encounters something which does not have a defined StructTypes.StructType to use for serializing to JSON, it will fallback to converting the objects to strings, like the default recursive=false option does. Handles the key exception specially, by printing errors and stacktraces using Base.showerror.

julia> f() = try
                throw(ArgumentError("Bad input"))
            catch e
                @error "Input error" exception=(e, catch_backtrace())
            end

julia> with_logger(f, FormatLogger(LoggingFormats.JSON(; recursive=true), stderr))
{"level":"error","msg":"Input error","module":"Main","file":"REPL[2]","line":4,"group":"REPL[2]","id":"Main_a226875f","kwargs":{"exception":"ERROR: ArgumentError: Bad input\nStacktrace:\n [1] f()\n   @ Main ./REPL[2]:2\n [2] with_logstate(f::Function, logstate::Any)\n   @ Base.CoreLogging ./logging.jl:511\n [3] with_logger(f::Function, logger::FormatLogger)\n   @ Base.CoreLogging ./logging.jl:623\n [4] top-level scope\n   @ REPL[3]:1\n"}}

`LogFmt`: Format log events as logfmt

LoggingFormats.LogFmt() is a function which formats the log message in the logfmt format. Example:

julia> using LoggingFormats, LoggingExtras

julia> with_logger(FormatLogger(LoggingFormats.LogFmt(), stderr)) do
           @info "hello, world"
           @error "something is wrong"
       end
level=info msg="hello, world" module=Main file="REPL[2]" line=2 group="REPL[2]" id=Main_6972c827
level=error msg="something is wrong" module=Main file="REPL[2]" line=3 group="REPL[2]" id=Main_2289c7f8

`Truncated`: Truncate long variables and messages

LoggingFormats.Truncated(max_var_len=5_000) is a function which formats data in similar manner as ConsoleLogger, but with truncation of string representation when it exceeds max_var_len. This format truncates the length of message itself, and truncates string representation of individual variables, but does not truncate the size of whole printed text.

See the examples:

julia> using LoggingFormats, LoggingExtras

julia> with_logger(FormatLogger(LoggingFormats.Truncated(30))) do
    short_var = "a"^5
    long_var = "a"^50
    @info "a short message" short_var long_var
    @info "a very long message "^20 short_var long_var
end
┌ Info: a short message
│   short_var = aaaaa
│   long_var = aaaaaaaaaaaa…
└ @ Main REPL[46]:4
┌ Info: a very long message a very lo…
│   short_var = aaaaa
│   long_var = aaaaaaaaaaaa…
└ @ Main REPL[46]:5

jameswrigley / loggingformats.jl Goto Github PK