Logger File Backend

https://hexdocs.pm/logger_file_backend
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A simple Elixir Logger backend that writes logs to a file, tolerating log file renames for use with...
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### Phoenix Project Dependencies in Elixir

Source: https://hexdocs.pm/logger_file_backend/index

This Elixir code snippet shows how to add the logger_file_backend dependency to a Phoenix project's mix.exs file. It ensures that the logger_file_backend is included in the application's dependencies and started along with other applications.

```elixir
def application do
    [applications:
      ...,
      :logger_file_backend,
      ...
      ]
end

defp deps do
  [ ...
    {:logger_file_backend, "~> 0.0.10"},
  ]
end
```

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

### Configure LoggerFileBackend in Elixir

Source: https://hexdocs.pm/logger_file_backend/index

This Elixir code snippet demonstrates how to configure LoggerFileBackend in your application's config file. It specifies the backend to be loaded and its associated file path and logging level. This setup ensures that error messages are directed to a designated file.

```elixir
config :logger,
  backends: [{LoggerFileBackend, :error_log}]

config :logger, :error_log,
  path: "/var/log/my_app/error.log",
  level: :error
```

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

### Runtime Configuration of LoggerFileBackend

Source: https://hexdocs.pm/logger_file_backend/index

This Elixir code shows how to add and configure a LoggerFileBackend at runtime. It allows for dynamic setting of the log file path, format, metadata, and metadata filters without modifying the application's configuration files.

```elixir
Logger.add_backend {LoggerFileBackend, :debug}
Logger.configure_backend {LoggerFileBackend, :debug},
  path: "/path/to/debug.log",
  format: ...,
  metadata: ...,
  metadata_filter: ...
```

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

### Phoenix Framework Integration for LoggerFileBackend

Source: https://hexdocs.pm/logger_file_backend/readme

This Elixir code snippet demonstrates how to integrate LoggerFileBackend with the Phoenix framework. It shows the necessary additions to the `mix.exs` file to include the logger_file_backend dependency and application.

```elixir
def application do
    [applications:
      [...,
        :logger_file_backend,
        ...
      ]
    ]
end

defp deps do
  [ ...
    {:logger_file_backend, "~> 0.0.10"},
  ]
end
```

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

### Elixir LoggerFileBackend Function Specifications

Source: https://hexdocs.pm/logger_file_backend/LoggerFileBackend

Specifies the function signatures and return types for the LoggerFileBackend module. These include callback implementations for `:gen_event` handling (`handle_call`, `handle_event`, `handle_info`, `init`) and a `prune` function for processing character data. These specs aid in understanding the module's behavior and interactions.

```Elixir
@spec prune(IO.chardata()) :: IO.chardata()

```

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

### Multiple Log File Configuration in Elixir

Source: https://hexdocs.pm/logger_file_backend/index

This Elixir configuration sets up multiple LoggerFileBackend instances, each directed to a different log file with specific logging levels. This allows for granular control over log file management based on message severity.

```elixir
config :logger,
  backends: [{LoggerFileBackend, :info},
             {LoggerFileBackend, :error}]

config :logger, :info,
  path: "/path/to/info.log",
  level: :info

config :logger, :error,
  path: "/path/to/error.log",
  level: :error
```

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

### Filtering Logs by Metadata in Elixir

Source: https://hexdocs.pm/logger_file_backend/index

This Elixir configuration demonstrates filtering log messages based on metadata. It shows how to log only messages originating from a specific application or messages containing custom metadata keys, ensuring logs are relevant and organized.

```elixir
# in a config file:
config :logger,
  backends: [{LoggerFileBackend, :device_1}]

config :logger, :device_1,
  path: "/path/to/device_1.log",
  level: :debug,
  metadata_filter: [device: 1]

# Usage:
# anywhere in the code:
Logger.info("statement", device: 1)

# or, for a single process, e.g., a GenServer:
# in init/1:
Logger.metadata(device: 1)
# ^ sets device: 1 for all subsequent log statements from this process.

# Later, in other code (handle_cast/2, etc.)
Logger.info("statement") # <= already tagged with the device_1 metadata
```

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

### Filtering Metadata for LoggerFileBackend in Elixir

Source: https://hexdocs.pm/logger_file_backend/readme

This Elixir configuration shows how to filter log messages based on metadata using LoggerFileBackend. It specifically logs messages from the `:ui` application and demonstrates logging with custom metadata keys.

```elixir
# in a config file:
config :logger,
  backends: [{LoggerFileBackend, :ui}]

config :logger, :ui,
  path: "/path/to/ui.log",
  level: :info,
  metadata_filter: [application: :ui]

# Usage:
# anywhere in the code:
Logger.info("statement", device: 1)

# or, for a single process, e.g., a GenServer:
# in init/1:
Logger.metadata(device: 1)
# ^ sets device: 1 for all subsequent log statements from this process.

# Later, in other code (handle_cast/2, etc.)
Logger.info("statement") # <= already tagged with the device_1 metadata
```

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

### Elixir LoggerFileBackend Types

Source: https://hexdocs.pm/logger_file_backend/LoggerFileBackend

Defines the custom types used within the LoggerFileBackend module. These types specify the expected data structures for file handles, log formats, file inodes, log levels, metadata, and file paths. They are essential for type checking and ensuring correct data flow within the backend.

```Elixir
@type file() :: :file.io_device()

```

```Elixir
@type format() :: String.t()

```

```Elixir
@type inode() :: integer()

```

```Elixir
@type level() :: Logger.level()

```

```Elixir
@type metadata() :: [atom()]

```

```Elixir
@type path() :: String.t()

```
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