76 lines
1.5 KiB
Markdown
76 lines
1.5 KiB
Markdown
# ln: The Natural Logger for Lua
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This is a clone of [ln](https://github.com/Xe/ln) for Lua. ln works by using
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key->value pairs to create structured logging output. By default, this outputs
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logs formatted similar to [logfmt][logfmt].
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[logfmt]: https://www.brandur.org/logfmt
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Example:
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```lua
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local ln = require "ln"
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ln.log {foo = "bar"}
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-- time="2019-12-25T13:24:00" foo=bar
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```
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It also supports multiple tables:
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```lua
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local ln = require "ln"
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ln.log({foo = "bar"}, {needs_space = "a string value with spaces"})
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-- time="2019-12-25T13:24:00" foo=bar needs_space="a string value with spaces"
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```
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And logging errors:
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```lua
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local ln = require "ln"
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local result, err = thing_that_could_fail()
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if err ~= nil then
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ln.err(err, {tried = "thing_that_could_fail()"})
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end
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-- time="2019-12-25T13:27:32" err="vibe check failed" tried=thing_that_could_fail()
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```
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And outputting logs as JSON:
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```
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local ln = require "ln"
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ln.default_logger.formatter = ln.JSONFormatter:new()
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ln.log {foo = "bar"}
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-- {"foo":"bar","time":"2019-12-25T13:27:32"}
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```
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Or creating your own logger instance:
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```lua
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local ln = require "ln"
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local lgr = ln.Logger:new()
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lgr:log {foo = "bar"}
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-- time="2019-12-25T13:27:32" foo=bar
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```
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Or custom filters
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```lua
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local lgr = ln.Logger:new {
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filters = {
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function(message)
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if string.find(message, "debug=true") and os.getenv("DEBUG") ~= "YES" then
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return false
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end
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end,
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print,
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}
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}
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lgr:log {debug = "true", line = "PRIVMSG #foo :bar", dir = "out"}
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```
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This will make the log line only show up when `DEBUG` is set to `"YES"`. |