logging

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# 40ants-logging - Functions to configure log4cl for different contexts: REPL, Backend, Command Line Application.

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## 40ANTS-LOGGING ASDF System Details

* Version: 0.1.0

* Description: Functions to configure log4cl for different contexts: `REPL`, Backend, Command Line Application.

* Licence: Unlicense

* Author: Alexander Artemenko <svetlyak.40wt@gmail.com>

* Homepage: [https://40ants.com/logging/][3eb9]

* Bug tracker: [https://github.com/40ants/logging/issues][cd63]

* Source control: [GIT][0aac]

[![](https://github-actions.40ants.com/40ants/logging/matrix.svg?only=ci.run-tests)][2779]

![](http://quickdocs.org/badge/40ants-logging.svg)

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## Installation

You can install this library from Quicklisp, but you want to receive updates quickly, then install it from Ultralisp.org:

```
(ql-dist:install-dist "http://dist.ultralisp.org/"
                      :prompt nil)
(ql:quickload :40ants-logging)
```
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## Usage

This small library encapsulates a logging approach for all `40A`nts projects. It provides
a few functions to setup structured logging for two kinds of applications: backend and command-line utility.

For a backend you need to call [`40ants-logging:setup-for-backend`][d0af] function. It configures `LOG4CL` to output all logs to `STDOUT` in `JSON` format. We are doing this because these days most backends are running in the Docker or Kubernetes where easiest way to collect logs is to capture daemon's `STDOUT`.

For a command line utilities we are configuring `LOG4CL` to use plaintext format. Call [`40ants-logging:setup-for-cli`][78f4] to make the job. Why `LOG:CONFIG` is not enought? `LOG:CONFIG` uses `LOG4CL` appenders which are not aware of fields added by structured logging macro [`log4cl-extras/context:with-fields`][b464].

You can also build an example app to test how this logging works:

```
./build-example.sh
./logging-example --help
```
Here is how it's output looks like for `CLI` mode:

```
% ./logging-example
<INFO> [2023-03-05T10:44:25.861365Z] 40ants-logging-example/cli cli.lisp (run-as-cli) Running as a command line application.
  Fields:
    request-id: 120002
<INFO> [2023-03-05T10:44:25.864960Z] 40ants-logging-example/cli cli.lisp (run-cli-loop) Sleeping 1 seconds
  Fields:
    request-id: 120002
    iteration: 0
<INFO> [2023-03-05T10:44:26.865200Z] 40ants-logging-example/cli cli.lisp (run-cli-loop) Sleeping 1 seconds
  Fields:
    request-id: 120002
    iteration: 1
...
```
and for backend mode:

```json
% ./logging-example --backend
{"fields":{"logger":"40ants-logging-example/cli","func":"run-as-backend","file":"cli.lisp","request-id":"120002"},"level":"INFO","message":"Running as a backend.","timestamp":"2023-03-05T10:46:12.812570Z"}
{"fields":{"logger":"40ants-logging-example/cli","func":"run-backend-loop","file":"cli.lisp","request-id":"120002","iteration":0},"level":"INFO","message":"Sleeping 15 seconds","timestamp":"2023-03-05T10:46:12.822253Z"}
{"fields":{"logger":"40ants-logging-example/cli","func":"run-backend-loop","file":"cli.lisp","request-id":"120002","iteration":1},"level":"INFO","message":"Sleeping 15 seconds","timestamp":"2023-03-05T10:46:27.822530Z"}
...
```
If you are using [`40ants-slynk`][04ac] system to setup a Slynk server, then [`40ants-logging:setup-for-repl`][d1f2] function will be called automatically on connect to the repl. You can observe logging configuration by like this:

```
CL-USER> (log:config)
ROOT, DEBUG
|
+-(1)-#<STABLE-THIS-CONSOLE-APPENDER {10055B18F3}>
|     with #<JSON-LAYOUT {10055B6AD3}>
|     :immediate-flush NIL
|     :flush-interval  1
|     :stream-owner    NIL
|     :stream          #<SB-SYS:FD-STREAM for "standard output" {1001D016C3}>
|     :message-count   0
|     :filter          :INFO
|
+-(2)-#<STABLE-THIS-CONSOLE-APPENDER {10023FB1D3}>
      with #<PLAIN-LAYOUT {10055B46D3}>
      :immediate-flush NIL
      :flush-interval  1
      :stream-owner    NIL
      :stream          #<SLYNK-GRAY::SLY-OUTPUT-STREAM {1001D00153}>
      :message-count   0
      :filter          :WARN
```
To change log level only for the `REPL`, call `(40ants-logging:setup-for-repl :level :warn)` function. If you will change log level via standard function of `LOG4CL`: `(log:config :warn)`, it will change the global logging level which will affect the backend's log in `JSON` format.

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## API

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### [function](a285) `40ants-logging:setup-for-backend` &key (level \*default-level\*)

Configures `LOG4CL` for logging in `JSON` format.

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### [function](8984) `40ants-logging:setup-for-cli` &key (level \*default-level\*)

Configures `LOG4CL` for logging in plain-text format with context fields support.

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### [function](3e3a) `40ants-logging:setup-for-repl` &key (level \*level\*) (stream \*debug-io\*)

Configures `LOG4CL` for logging in `REPL` when you connect to the running lisp image already configured as a backend or `CLI` application.

If you are using [`40ants-slynk`][04ac] system, this function will be called automatically
when your `SLY` connects to the image.

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### [function](8f2a) `40ants-logging:remove-repl-appender`

Returns configuration the state as it was after [`setup-for-backend`][d0af] or [`setup-for-cli`][78f4] call.

If you are using [`40ants-slynk`][04ac] system, this function will be called automatically
when your `SLY` disconnects from the image.


[b464]: https://40ants.com/log4cl-extras/#x-28LOG4CL-EXTRAS-2FCONTEXT-3AWITH-FIELDS-20-2840ANTS-DOC-2FLOCATIVES-3AMACRO-29-29
[3eb9]: https://40ants.com/logging/
[d0af]: https://40ants.com/logging/#x-2840ANTS-LOGGING-3ASETUP-FOR-BACKEND-20FUNCTION-29
[78f4]: https://40ants.com/logging/#x-2840ANTS-LOGGING-3ASETUP-FOR-CLI-20FUNCTION-29
[d1f2]: https://40ants.com/logging/#x-2840ANTS-LOGGING-3ASETUP-FOR-REPL-20FUNCTION-29
[04ac]: https://40ants.com/slynk/#x-28-23A-28-2812-29-20BASE-CHAR-20-2E-20-2240ants-slynk-22-29-20ASDF-2FSYSTEM-3ASYSTEM-29
[0aac]: https://github.com/40ants/logging
[2779]: https://github.com/40ants/logging/actions
[a285]: https://github.com/40ants/logging/blob/8f32a96d500ee95bb43f1d98b6ee6d6782b7149b/src/core.lisp#L22
[3e3a]: https://github.com/40ants/logging/blob/8f32a96d500ee95bb43f1d98b6ee6d6782b7149b/src/core.lisp#L36
[8f2a]: https://github.com/40ants/logging/blob/8f32a96d500ee95bb43f1d98b6ee6d6782b7149b/src/core.lisp#L53
[8984]: https://github.com/40ants/logging/blob/8f32a96d500ee95bb43f1d98b6ee6d6782b7149b/src/core.lisp#L63
[cd63]: https://github.com/40ants/logging/issues

* * *
###### [generated by [40ANTS-DOC](https://40ants.com/doc/)]


40ants-asdf-system

40ants-logging/core

Functions to configure log4cl for different contexts: REPL, Backend, Command Line Application.

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