A set of logging utilities for Nim.
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✓ File rotation
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✓ Compression
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✓ Templated log file name
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✓ Templated log messages
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✓ Threaded log buffering
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✓ Async log buffering
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✓ Logging, file rotation and compression do not block the caller
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✓ Sensible defaults: log to "<appname>.<date>.log", daily log rotation
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✓ Log to systemd Journald. Support structured entries.
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✓ Support Linux, OSX, Windows
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✓ Functional-tested
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❏ Logging hierarchy
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❏ Do not crash the application on write failure (e.g. broken or full disk, permission errors) - switch to logging to stderr
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❏ Rotate logfile on SIGHUP signal
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❏ Structured logging and optional fields
$ # install Nim using APT or from the upstream website
$ sudo apt-get install nim
$ # install nimble and then:
$ nimble install moreloggingimport morelogging
let log = newAsyncFileLogger()
log.debug("debug")
log.info("info")
log.warn("warn")
log.error("error")
log.fatal("fatal")The following formatters are supported:
$date $time $datetime $app $appdir $appname $levelid $levelname
Messages with level below level_threshold are ignored.
If buffer_size is positive, messages are buffered internally up to writeout_interval_ms
Messages with level >= flush_threshold are flushed out immediately.
proc newAsyncFileLogger*(
filename_tpl = "$app.$y$MM$dd.log",
flush_threshold = lvlError,
fmtStr = "$datetime $levelname ",
level_threshold = lvlAll,
mode: FileMode = fmAppend,
writeout_interval_ms = 100,
buffer_size = 1_048_576
): AsyncFileLogger =
proc newThreadFileLogger*(
filename_tpl = "$app.$y$MM$dd.log",
fmtStr = "$datetime $levelname ",
level_threshold = lvlAll,
mode: FileMode = fmAppend,
writeout_interval_ms = 100,
): ThreadFileLogger =
proc newThreadRotatingFileLogger*(
compress = false,
filename_tpl = "$app.$y$MM$dd.log",
fmtStr = "$datetime $levelname ",
level_threshold = lvlAll,
mode: FileMode = fmAppend,
rotate_interval = "1d",
writeout_interval_ms = 100,
): ThreadRotatingFileLoggerJournald supports logging user-defined key-value pairs and provides fast indexing.
Enable with -d:systemd
let log = newJournaldLogger()
log.info("hello world", {"key_1": "value_1"})Keys are converted to uppercase. They can contain underscores but not as the first character.
JournaldLogger will automatically add CODE_FILE, CODE_FUNC, CODE_LINE keys to show the filename, function and line number that generated the log message.
Note: '--stackTrace:on' and '--lineTrace:on' are required when building in release mode to enable this feature.
You can override them by passing the keys in uppercase with your own values.
sudo journalctl -e -o json-pretty KEY_1=value_1 -n1 --no-pager
{
"PRIORITY" : "5",
"_TRANSPORT" : "journal",
"_UID" : "1000",
"_GID" : "1000",
"MESSAGE" : "hello world",
"KEY_1" : "value_1",
"CODE_FUNC" : "myfunction",
"CODE_FILE" : "mytest.nim",
"CODE_LINE" : "24",
< other lines redacted >
< ... >
}
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