## ⚠️ Breaking

The `log.<mode>.<logger>` style config has been dropped. If you used it,
please check the new config manual & app.example.ini to make your
instance output logs as expected.

Although many legacy options still work, it's encouraged to upgrade to
the new options.

The SMTP logger is deleted because SMTP is not suitable to collect logs.

If you have manually configured Gitea log options, please confirm the
logger system works as expected after upgrading.

## Description

Close #12082 and maybe more log-related issues, resolve some related
FIXMEs in old code (which seems unfixable before)

Just like rewriting queue #24505 : make code maintainable, clear legacy
bugs, and add the ability to support more writers (eg: JSON, structured
log)

There is a new document (with examples): `logging-config.en-us.md`

This PR is safer than the queue rewriting, because it's just for
logging, it won't break other logic.

## The old problems

The logging system is quite old and difficult to maintain:
* Unclear concepts: Logger, NamedLogger, MultiChannelledLogger,
SubLogger, EventLogger, WriterLogger etc
* Some code is diffuclt to konw whether it is right:
`log.DelNamedLogger("console")` vs `log.DelNamedLogger(log.DEFAULT)` vs
`log.DelLogger("console")`
* The old system heavily depends on ini config system, it's difficult to
create new logger for different purpose, and it's very fragile.
* The "color" trick is difficult to use and read, many colors are
unnecessary, and in the future structured log could help
* It's difficult to add other log formats, eg: JSON format
* The log outputer doesn't have full control of its goroutine, it's
difficult to make outputer have advanced behaviors
* The logs could be lost in some cases: eg: no Fatal error when using
CLI.
* Config options are passed by JSON, which is quite fragile.
* INI package makes the KEY in `[log]` section visible in `[log.sub1]`
and `[log.sub1.subA]`, this behavior is quite fragile and would cause
more unclear problems, and there is no strong requirement to support
`log.<mode>.<logger>` syntax.


## The new design

See `logger.go` for documents.


## Screenshot

<details>


![image](https://github.com/go-gitea/gitea/assets/2114189/4462d713-ba39-41f5-bb08-de912e67e1ff)


![image](https://github.com/go-gitea/gitea/assets/2114189/b188035e-f691-428b-8b2d-ff7b2199b2f9)


![image](https://github.com/go-gitea/gitea/assets/2114189/132e9745-1c3b-4e00-9e0d-15eaea495dee)

</details>

## TODO

* [x] add some new tests
* [x] fix some tests
* [x] test some sub-commands (manually ....)

---------

Co-authored-by: Jason Song <i@wolfogre.com>
Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: Giteabot <teabot@gitea.io>

Change all license headers to comply with REUSE specification.

Fix #16132

Co-authored-by: flynnnnnnnnnn <flynnnnnnnnnn@github>
Co-authored-by: John Olheiser <john.olheiser@gmail.com>

* gofumpt -w -l .

* gofumpt -w -l -extra .

* Add linter

* manual fix

* change make fmt

The io/ioutil package has been deprecated as of Go 1.16, see
https://golang.org/doc/go1.16#ioutil. This commit replaces the existing
io/ioutil functions with their new definitions in io and os packages.

Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>

Co-authored-by: techknowlogick <techknowlogick@gitea.io>

This PR updates golangci-lint to the latest version 1.31.0.

The upgrade introduced a new check for which I've fixed or disabled most cases.

Signed-off-by: kolaente <k@knt.li>

* Panic don't fatal on create new logger

Fixes #5854

Signed-off-by: Andrew Thornton <art27@cantab.net>

* partial broken

* Update the logging infrastrcture

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Reset the skip levels for Fatal and Error

Signed-off-by: Andrew Thornton <art27@cantab.net>

* broken ncsa

* More log.Error fixes

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Remove nal

* set log-levels to lowercase

* Make console_test test all levels

* switch to lowercased levels

* OK now working

* Fix vetting issues

* Fix lint

* Fix tests

* change default logging to match current gitea

* Improve log testing

Signed-off-by: Andrew Thornton <art27@cantab.net>

* reset error skip levels to 0

* Update documentation and access logger configuration

* Redirect the router log back to gitea if redirect macaron log but also allow setting the log level - i.e. TRACE

* Fix broken level caching

* Refactor the router log

* Add Router logger

* Add colorizing options

* Adjust router colors

* Only create logger if they will be used

* update app.ini.sample

* rename Attribute ColorAttribute

* Change from white to green for function

* Set fatal/error levels

* Restore initial trace logger

* Fix Trace arguments in modules/auth/auth.go

* Properly handle XORMLogger

* Improve admin/config page

* fix fmt

* Add auto-compression of old logs

* Update error log levels

* Remove the unnecessary skip argument from Error, Fatal and Critical

* Add stacktrace support

* Fix tests

* Remove x/sync from vendors?

* Add stderr option to console logger

* Use filepath.ToSlash to protect against Windows in tests

* Remove prefixed underscores from names in colors.go

* Remove not implemented database logger

This was removed from Gogs on 4 Mar 2016 but left in the configuration
since then.

* Ensure that log paths are relative to ROOT_PATH

* use path.Join

* rename jsonConfig to logConfig

* Rename "config" to "jsonConfig" to make it clearer

* Requested changes

* Requested changes: XormLogger

* Try to color the windows terminal

If successful default to colorizing the console logs

* fixup

* Colorize initially too

* update vendor

* Colorize logs on default and remove if this is not a colorizing logger

* Fix documentation

* fix test

* Use go-isatty to detect if on windows we are on msys or cygwin

* Fix spelling mistake

* Add missing vendors

* More changes

* Rationalise the ANSI writer protection

* Adjust colors on advice from @0x5c

* Make Flags a comma separated list

* Move to use the windows constant for ENABLE_VIRTUAL_TERMINAL_PROCESSING

* Ensure matching is done on the non-colored message - to simpify EXPRESSION

This PR gitea'ises the macaron.Recovery() handler meaning that in
the event of panic we get proper gitea 500 pages and the stacktrace
is logged with the gitea logger.

Signed-off-by: Andrew Thornton <art27@cantab.net>