Merge pull request #2609 from fishcakez/logger_ansi_console

Add ANSI support to console logger

Author: José Valim

lib/logger/lib/logger.ex

@@ -139,12 +139,30 @@ defmodule Logger do
     * `:metadata` - the metadata to be printed by `$metadata`.
       Defaults to an empty list (no metadata)
 
+    * `:colors` - a keyword list of coloring options.
+
+  The supported keys in the `:colors` keyword list are:
+
+    * `:enabled` - boolean value that allows for switching the
+    coloring on and off. Defaults to: `false`
+
+    * `:debug` - color for debug messages. Defaults to: `:magenta`
+
+    * `:info` - color for info messages. Defaults to: `:normal`
+
+    * `:warn` - color for warn messages. Defaults to: `:yellow`
+
+    * `:error` - color for error messages. Defaults to: `:red`
+
+  See the `IO.ANSI` module for a list of colors and attributes.
+
   Here is an example on how to configure the `:console` in a
   `config/config.exs` file:
 
       config :logger, :console,
         format: "$date $time [$level] $metadata$message\n",
-        metadata: [:user_id]
+        metadata: [:user_id],
+        colors: [enabled: true]
 
   You can read more about formatting in `Logger.Formatter`.
 

lib/logger/lib/logger/backends/console.ex

@@ -30,7 +30,8 @@ defmodule Logger.Backends.Console do
   ## Helpers
 
   defp configure(options) do
-    console = Keyword.merge(Application.get_env(:logger, :console, []), options)
+    env = Application.get_env(:logger, :console, [])
+    console = configure_merge(env, options)
     Application.put_env(:logger, :console, console)
 
     format = console
@@ -39,11 +40,41 @@ defmodule Logger.Backends.Console do
 
     level    = Keyword.get(console, :level)
     metadata = Keyword.get(console, :metadata, [])
-    %{format: format, metadata: metadata, level: level}
+    colors   = configure_colors(console)
+    %{format: format, metadata: metadata, level: level, colors: colors}
   end
 
-  defp log_event(level, msg, ts, md, %{format: format, metadata: metadata}) do
-    :io.put_chars :user,
-      Logger.Formatter.format(format, level, msg, ts, Dict.take(md, metadata))
+  defp configure_merge(env, options) do
+    env_colors = Keyword.get(env, :colors, [])
+    opts_colors = Keyword.get(options, :colors, [])
+    colors = Keyword.merge(env_colors, opts_colors)
+
+    Keyword.merge(env, options)
+    |> Keyword.put(:colors, colors)
+  end
+
+  defp configure_colors(console) do
+    colors  = Keyword.get(console, :colors, [])
+    debug   = Keyword.get(colors, :debug, :magenta)
+    info    = Keyword.get(colors, :info, :normal)
+    warn    = Keyword.get(colors, :warn, :yellow)
+    error   = Keyword.get(colors, :error, :red)
+    enabled = Keyword.get(colors, :enabled, false)
+    %{debug: debug, info: info, warn: warn, error: error, enabled: enabled}
+  end
+
+  defp log_event(level, msg, ts, md, %{colors: colors} = state) do
+    ansidata = format_event(level, msg, ts, md, state)
+    chardata = color_event(level, ansidata, colors)
+    :io.put_chars(:user, chardata)
   end
+
+  defp format_event(level, msg, ts, md, %{format: format, metadata: metadata}) do
+    Logger.Formatter.format(format, level, msg, ts, Dict.take(md, metadata))
+  end
+
+  defp color_event(level, data, %{enabled: enabled} = colors) do
+    IO.ANSI.format([Map.fetch!(colors, level) | data], enabled)
+  end
+
 end

lib/logger/test/logger/backends/console_test.exs

@@ -4,7 +4,8 @@ defmodule Logger.Backends.ConsoleTest do
 
   setup do
     on_exit fn ->
-      :ok = Logger.configure_backend(:console, [format: nil, level: nil, metadata: []])
+      :ok = Logger.configure_backend(:console,
+          [format: nil, level: nil, metadata: [], colors: [enabled: false]])
     end
   end
 
@@ -49,4 +50,48 @@ defmodule Logger.Backends.ConsoleTest do
       Logger.debug("hello")
     end) == ""
   end
-end
+
+  test "can configure colors" do
+    Logger.configure_backend(:console, [format: "$message", colors: [enabled: true]])
+
+    assert capture_log(fn ->
+      Logger.debug("hello")
+    end) == IO.ANSI.magenta() <> "hello" <> IO.ANSI.reset()
+
+    Logger.configure_backend(:console, [colors: [debug: :cyan]])
+
+    assert capture_log(fn ->
+      Logger.debug("hello")
+    end) == IO.ANSI.cyan() <> "hello" <> IO.ANSI.reset()
+
+    assert capture_log(fn ->
+      Logger.info("hello")
+    end) == IO.ANSI.normal() <> "hello" <> IO.ANSI.reset()
+
+    Logger.configure_backend(:console, [colors: [info: :cyan]])
+
+    assert capture_log(fn ->
+      Logger.info("hello")
+    end) == IO.ANSI.cyan() <> "hello" <> IO.ANSI.reset()
+
+    assert capture_log(fn ->
+      Logger.warn("hello")
+    end) == IO.ANSI.yellow() <> "hello" <> IO.ANSI.reset()
+
+    Logger.configure_backend(:console, [colors: [warn: :cyan]])
+
+    assert capture_log(fn ->
+      Logger.warn("hello")
+    end) == IO.ANSI.cyan() <> "hello" <> IO.ANSI.reset()
+
+    assert capture_log(fn ->
+      Logger.error("hello")
+    end) == IO.ANSI.red() <> "hello" <> IO.ANSI.reset()
+
+    Logger.configure_backend(:console, [colors: [error: :cyan]])
+
+    assert capture_log(fn ->
+      Logger.error("hello")
+    end) == IO.ANSI.cyan() <> "hello" <> IO.ANSI.reset()
+  end
+end