Ring Logger

https://hexdocs.pm/ring_logger/
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Ring Logger is an in-memory ring buffer backend for the Elixir Logger with convenience methods for...
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### Manually start RingLogger backend

Source: https://hexdocs.pm/ring_logger

Starts the RingLogger backend manually by adding it as a Logger backend and configuring its max_size. This is an alternative to configuring via config.exs.

```elixir
Logger.add_backend(RingLogger)
Logger.configure_backend(RingLogger, max_size: 1024)
```

--------------------------------

### Launch RingLogger TUI

Source: https://hexdocs.pm/ring_logger

Starts the text-based user interface for viewing logs.

```elixir
iex> RingLogger.viewer()
```

--------------------------------

### Configure RingLogger backend in config.exs

Source: https://hexdocs.pm/ring_logger

Configures the RingLogger backend in config.exs. This removes the default :console backend and sets options like persist_path, persist_seconds, max_size, and custom buffers. The example shows multiple configuration options, including separate buffers for error/warning messages and for all log levels, as well as client options.

```elixir
import Config

# Add the RingLogger backend. This removes the default :console backend.
config :logger, backends: [RingLogger]

# Periodically save logs to a file, and load logs on GenServer start from this file
config :logger, RingLogger, persist_path: "./myapp.log", persist_seconds: 300

# Save messages to one circular buffer that holds 1024 entries.
config :logger, RingLogger, max_size: 1024

# Separate out `:error` and `:warning` messages to their own circular buffer.
# All other log messages are stored in the default circular buffer.
config :logger, RingLogger, buffers: %{
  errors: %{
    levels: [:error, :warning],
    max_size: 1024
  }
}

# Specify circular buffers for all log levels. The default circular buffer won't
# be used in this example configuration.
config :logger, RingLogger, buffers: %{
  low_priority: %{
    levels: [:warning, :notice, :info, :debug],
    max_size: 1024
  },
  high_priority: %{
    levels: [:emergency, :alert, :critical, :error],
    max_size: 1024
  }
}

# You can also configure `RingLogger.Client` options to be used
# with every client by default
config :logger, RingLogger,
  application_levels: %{my_app: :error},
  colors: [debug: :yellow],
  level: :debug
```

--------------------------------

### Attach to RingLogger and receive logs

Source: https://hexdocs.pm/ring_logger

Adds the RingLogger backend and attaches to it to start receiving log messages in the console.

```elixir
iex> Logger.add_backend(RingLogger)
{:ok, #PID<0.199.0>}
iex> RingLogger.attach
:ok
iex> require Logger
iex> Logger.info("hello")
:ok

14:04:52.516 [info]  hello
```

--------------------------------

### Prioritize Module Over Application Filtering

Source: https://hexdocs.pm/ring_logger

Demonstrates that module_levels take precedence over application_levels when both are provided.

```elixir
iex> RingLogger.attach(application_levels: %{my_app: :info}, module_levels: %{MyApp.Important => :debug})
```

--------------------------------

### Combine Module and Global Log Levels

Source: https://hexdocs.pm/ring_logger

Sets a specific level for a module while applying a different default level for all other modules.

```elixir
iex> RingLogger.attach(module_levels: %{MyModule => :debug}, level: :warn)
```

--------------------------------

### Retrieve raw log entries with RingLogger.get/0

Source: https://hexdocs.pm/ring_logger

Returns a list of raw log entries from the RingLogger buffer. Each entry includes the log level, message, timestamp, and metadata such as pid, application, module, function, file, and line.

```elixir
iex> RingLogger.get
[
  debug: {Logger, "8", {{2018, 2, 5}, {17, 44, 7, 675}},
   [
     pid: #PID<0.139.0>,
     application: :example,
     module: Example,
     function: "log/1",
     file: "ring_logger/example/lib/example.ex",
     line: 11
   ]},
  debug: {Logger, "9", {{2018, 2, 5}, {17, 44, 8, 676}},
   [
     pid: #PID<0.139.0>,
     application: :example,
     module: Example,
     function: "log/1",
     file: "ring_logger/example/lib/example.ex",
     line: 11
   ]},
  debug: {Logger, "10", {{2018, 2, 5}, {17, 44, 9, 677}},
   [
     pid: #PID<0.139.0>,
     application: :example,
     module: Example,
     function: "log/1",
     file: "ring_logger/example/lib/example.ex",
     line: 11
   ]}
]
```

--------------------------------

### Attach RingLogger with custom formatter and test logging

Source: https://hexdocs.pm/ring_logger

Attaches RingLogger with the CustomFormatter and metadata for file and line, then logs a test message. The output shows the formatted message with the source location.

```elixir
iex> RingLogger.attach(format: {CustomFormatter, :format}, metadata: [:file, :line])
:ok
iex> require Logger
Logger
iex> Logger.info("Important message!")
:ok
Important message! iex:4
```

--------------------------------

### Filter Application Log Levels

Source: https://hexdocs.pm/ring_logger

Uses the :application_levels option to set a log level for all modules within a specific OTP application.

```elixir
iex> RingLogger.attach(application_levels: %{my_app: :info})
```

--------------------------------

### View recent log entries with RingLogger.tail

Source: https://hexdocs.pm/ring_logger

Retrieves and displays the most recent log entries stored in the buffer.

```elixir
iex> RingLogger.tail

14:04:52.516 [info]  hello

14:11:54.397 [info]  Hello logger, how are you?

14:12:09.180 [info]  It's a nice day. Wouldn't you say?
:ok
```

--------------------------------

### Poll log messages with RingLogger.next

Source: https://hexdocs.pm/ring_logger

Detaches from real-time streaming and uses the next function to manually retrieve and print accumulated log messages.

```elixir
iex> RingLogger.detach
:ok
iex> Logger.info("Hello logger, how are you?")
:ok
iex> Logger.info("It's a nice day. Wouldn't you say?")
:ok
iex> RingLogger.next

14:04:52.516 [info]  hello

14:11:54.397 [info]  Hello logger, how are you?

14:12:09.180 [info]  It's a nice day. Wouldn't you say?
:ok
iex> RingLogger.next
:ok
```

--------------------------------

### Add ring_logger dependency in mix.exs

Source: https://hexdocs.pm/ring_logger

Adds the ring_logger package to the project's dependencies in mix.exs. The version specified is "~> 0.11".

```elixir
  def deps do
    [{:ring_logger, "~> 0.11"}]
  end
```

--------------------------------

### Filter logs with RingLogger.grep

Source: https://hexdocs.pm/ring_logger

Filters the log buffer using a regular expression to find specific entries.

```elixir
iex> RingLogger.grep(~r/[Nn]eedle/)

16:55:41.614 [info]  Needle in a haystack
```

--------------------------------

### Custom formatter module for RingLogger

Source: https://hexdocs.pm/ring_logger

Defines a CustomFormatter module that formats log messages with file and line metadata. The format/4 function rescues exceptions and falls back to the raw message.

```elixir
defmodule CustomFormatter do
  def format(_level, message, _timestamp, metadata) do
    "#{message} #{metadata[:file]}:#{metadata[:line]}\n"
  rescue
    _ -> message
  end
end
```

--------------------------------

### Save RingLogger log buffer to a file

Source: https://hexdocs.pm/ring_logger

Saves the current log buffer to /tmp/log.txt using RingLogger.save/1. Log messages are formatted the same way as RingLogger console output.

```elixir
iex> RingLogger.save("/tmp/log.txt")
:ok
```

--------------------------------

### Remove console backend in IEx

Source: https://hexdocs.pm/ring_logger

Disables the default console logger to prevent duplicate log messages in the IEx session.

```elixir
iex> Logger.remove_backend(:console)
:ok
```

--------------------------------

### Filter Module Log Levels

Source: https://hexdocs.pm/ring_logger

Uses the :module_levels option to set specific log levels for modules, such as ignoring debug messages for MyModule.

```elixir
iex> RingLogger.attach(module_levels: %{MyModule => :info})
```
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