Logger: Add color support for different log levels (#4931)

No related issue

config/config.example.yml

@@ -233,6 +233,17 @@ http_proxy:
 ##
 #log_level: Info
 
+##
+## Enables colors in logs. Useful for debugging purposes
+## This is overridden if "-k" or "--colorize"
+## are passed on the command line.
+## Colors are also disabled if the environment variable
+## NO_COLOR is present and has any value
+##
+## Accepted values: true, false
+## Default: true
+##
+#colorize_logs: false
 
 # -----------------------------
 #  Features

src/invidious.cr

@@ -122,6 +122,9 @@ Kemal.config.extra_options do |parser|
   parser.on("-l LEVEL", "--log-level=LEVEL", "Log level, one of #{LogLevel.values} (default: #{CONFIG.log_level})") do |log_level|
     CONFIG.log_level = LogLevel.parse(log_level)
   end
+  parser.on("-k", "--colorize", "Colorize logs") do
+    CONFIG.colorize_logs = true
+  end
   parser.on("-v", "--version", "Print version") do
     puts SOFTWARE.to_pretty_json
     exit
@@ -138,7 +141,7 @@ if CONFIG.output.upcase != "STDOUT"
   FileUtils.mkdir_p(File.dirname(CONFIG.output))
 end
 OUTPUT = CONFIG.output.upcase == "STDOUT" ? STDOUT : File.open(CONFIG.output, mode: "a")
-LOGGER = Invidious::LogHandler.new(OUTPUT, CONFIG.log_level)
+LOGGER = Invidious::LogHandler.new(OUTPUT, CONFIG.log_level, CONFIG.colorize_logs)
 
 # Check table integrity
 Invidious::Database.check_integrity(CONFIG)

src/invidious/config.cr

@@ -78,6 +78,8 @@ class Config
   property output : String = "STDOUT"
   # Default log level, valid YAML values are ints and strings, see src/invidious/helpers/logger.cr
   property log_level : LogLevel = LogLevel::Info
+  # Enables colors in logs. Useful for debugging purposes
+  property colorize_logs : Bool = false
   # Database configuration with separate parameters (username, hostname, etc)
   property db : DBConfig? = nil
 

src/invidious/helpers/logger.cr

@@ -1,3 +1,5 @@
+require "colorize"
+
 enum LogLevel
   All   = 0
   Trace = 1
@@ -10,7 +12,9 @@ enum LogLevel
 end
 
 class Invidious::LogHandler < Kemal::BaseLogHandler
-  def initialize(@io : IO = STDOUT, @level = LogLevel::Debug)
+  def initialize(@io : IO = STDOUT, @level = LogLevel::Debug, use_color : Bool = true)
+    Colorize.enabled = use_color
+    Colorize.on_tty_only!
   end
 
   def call(context : HTTP::Server::Context)
@@ -39,10 +43,22 @@ class Invidious::LogHandler < Kemal::BaseLogHandler
     @io.flush
   end
 
+  def color(level)
+    case level
+    when LogLevel::Trace then :cyan
+    when LogLevel::Debug then :green
+    when LogLevel::Info  then :white
+    when LogLevel::Warn  then :yellow
+    when LogLevel::Error then :red
+    when LogLevel::Fatal then :magenta
+    else                      :default
+    end
+  end
+
   {% for level in %w(trace debug info warn error fatal) %}
     def {{level.id}}(message : String)
       if LogLevel::{{level.id.capitalize}} >= @level
-        puts("#{Time.utc} [{{level.id}}] #{message}")
+        puts("#{Time.utc} [{{level.id}}] #{message}".colorize(color(LogLevel::{{level.id.capitalize}})))
       end
     end
   {% end %}