Colourise prefix via config

CHANGELOG.md

@@ -1,6 +1,9 @@
 # Changelog
 All notable changes to this project will be documented in this file.
 
+## [2.3.0] - 2025-10-05
+- Config block can now accept prefix colour options. Can be applied to the whole prefix or configure individual components.
+
 ## [2.2.1] - 2025-09-15
 - Fixed issue with ANSI exit codes breaking on string interpolation
 - Added strip_colour method to String which we now call when sending logs to file

README.md

@@ -62,6 +62,26 @@ This would result in logs in the following format:
 
 `[SystemName CurrentDate CurrentTime CorrelationId PID] Level : -- Message`
 
+#### Prefix Colourisation
+You can colourise different parts of the log prefix by providing a hash to style each component. It accepts strings, symbols or arrays of either:
+
+```ruby
+config = DVLA::Herodotus.config do |config|
+  config.prefix_colour = {
+    system: %w[blue bold],
+    date: 'green',
+    time: :yellow,
+    correlation: %w[magenta italic],
+    pid: %w[cyan],
+    level: %i[red bold],
+    separator: %w[white],
+    overall: %w[underline]
+  }
+end
+```
+Each key is optional, and you can simply use the `overall` key to style the whole prefix.
+---
+
 ### Syncing logs
 
 Herodotus allows you to Sync correlation_ids between instantiated HerodotusLogger objects. 
@@ -82,6 +102,7 @@ You can call `new_scenario` with the identifier just before each scenario to cre
 logger.new_scenario('Scenario Id')
 ```
 
+---
 ### Strings
 
 Also included is a series of additional methods on `String` that allow you to modify the colour and style of logs.
@@ -94,14 +115,14 @@ You can stack multiple method calls to add additional styling and use string int
 
 #### Available String Methods
 
-| Type | Examples |
-|------|----------|
-| Text Styles | **bold** <span style="opacity:0.6">dim</span> *italic* <u>underline</u> |
-| Colors | <span style="color:black">black</span> <span style="color:red">red</span> <span style="color:green">green</span> <span style="color:#B8860B">brown</span> <span style="color:#ffff00">yellow</span> <span style="color:blue">blue</span> <span style="color:magenta">magenta</span> <span style="color:cyan">cyan</span> <span style="color:grey">gray</span> <span style="color:white">white</span> |
-| Bright Colors | <span style="color:#ff5555">bright_red</span> <span style="color:#55ff55">bright_green</span> <span style="color:#5555ff">bright_blue</span> <span style="color:#ff55ff">bright_magenta</span> <span style="color:#55ffff">bright_cyan</span> |
-| Background Colors | <span style="background:black;color:white">bg_black</span> <span style="background:red;color:white">bg_red</span> <span style="background:green;color:white">bg_green</span> <span style="background:#B8860B;color:white">bg_brown</span> <span style="background:#ffff00;color:black">bg_yellow</span> <span style="background:blue;color:white">bg_blue</span> <span style="background:magenta;color:white">bg_magenta</span> <span style="background:cyan;color:black">bg_cyan</span> <span style="background:grey;color:white">bg_gray</span> <span style="background:white;color:black">bg_white</span> |
-| Bright Background Colors | <span style="background:#ff5555;color:white">bg_bright_red</span> <span style="background:#55ff55;color:black">bg_bright_green</span> <span style="background:#5555ff;color:white">bg_bright_blue</span> <span style="background:#ff55ff;color:white">bg_bright_magenta</span> <span style="background:#55ffff;color:black">bg_bright_cyan</span> |
-| Utility | strip_colour reverse_colour |
+| Type                      | Examples |
+|---------------------------|----------|
+| Text Styles               | **bold** <span style="opacity:0.6">dim</span> *italic* <u>underline</u> |
+| Colours                   | <span style="color:black">black</span> <span style="color:red">red</span> <span style="color:green">green</span> <span style="color:#B8860B">brown</span> <span style="color:#ffff00">yellow</span> <span style="color:blue">blue</span> <span style="color:magenta">magenta</span> <span style="color:cyan">cyan</span> <span style="color:grey">gray</span> <span style="color:white">white</span> |
+| Bright Colours            | <span style="color:#ff5555">bright_red</span> <span style="color:#55ff55">bright_green</span> <span style="color:#5555ff">bright_blue</span> <span style="color:#ff55ff">bright_magenta</span> <span style="color:#55ffff">bright_cyan</span> |
+| Background Colours        | <span style="background:black;color:white">bg_black</span> <span style="background:red;color:white">bg_red</span> <span style="background:green;color:white">bg_green</span> <span style="background:#B8860B;color:white">bg_brown</span> <span style="background:#ffff00;color:black">bg_yellow</span> <span style="background:blue;color:white">bg_blue</span> <span style="background:magenta;color:white">bg_magenta</span> <span style="background:cyan;color:black">bg_cyan</span> <span style="background:grey;color:white">bg_gray</span> <span style="background:white;color:black">bg_white</span> |
+| Bright Background Colours | <span style="background:#ff5555;color:white">bg_bright_red</span> <span style="background:#55ff55;color:black">bg_bright_green</span> <span style="background:#5555ff;color:white">bg_bright_blue</span> <span style="background:#ff55ff;color:white">bg_bright_magenta</span> <span style="background:#55ffff;color:black">bg_bright_cyan</span> |
+| Utility                   | strip_colour reverse_colour |
 
 #### To handle differences in spelling the following methods have been given aliases:
 | Alias         | Original       |
@@ -112,6 +133,8 @@ You can stack multiple method calls to add additional styling and use string int
 | reverse_color | reverse_colour |
 | strip_color   | strip_colour   |
 
+---
+
 ## Development
 
 Herodotus is very lightweight. Currently, all code to generate a new logger can be found in `herodotus.rb` and the code for the logger is in `herodotus_logger.rb` so that is the best place to start with any modifications

lib/dvla/herodotus.rb

@@ -10,7 +10,7 @@ class << self
       attr_accessor :main_logger
     end
 
-    CONFIG_ATTRIBUTES = %i[display_pid main].freeze
+    CONFIG_ATTRIBUTES = %i[display_pid main prefix_colour].freeze
 
     def self.config
       config ||= Struct.new(*CONFIG_ATTRIBUTES, keyword_init: true).new

lib/dvla/herodotus/herodotus_logger.rb

@@ -3,7 +3,7 @@
 module DVLA
   module Herodotus
     class HerodotusLogger < Logger
-      attr_accessor :system_name, :correlation_id, :main, :display_pid, :scenario_id
+      attr_accessor :system_name, :correlation_id, :main, :display_pid, :scenario_id, :prefix_colour
 
       # Initializes the logger
       # Sets a default correlation_id and creates the formatter
@@ -15,7 +15,8 @@ def initialize(system_name, *args, config: DVLA::Herodotus.config, **kwargs)
         @system_name = system_name
         @main = config[:main]
         @display_pid = config[:display_pid]
-
+        @prefix_colour = config[:prefix_colour] || {}
+        validate_colour_config if @prefix_colour.any?
         @correlation_id = SecureRandom.uuid[0, 8]
         set_formatter
 
@@ -65,19 +66,75 @@ def sync_correlation_ids
       end
 
       # Sets the format of the log.
-      # Needs to be called each time correlation_id is changed after initialization in-order for the changes to take affect.
+      # Needs to be called each time correlation_id is changed after initialization in-order for the changes to take effect.
       def set_formatter
         self.formatter = proc do |severity, _datetime, _progname, msg|
-          "[#{@system_name} " \
-            "#{Time.now.strftime('%Y-%m-%d %H:%M:%S')} " \
-            "#{@correlation_id}" \
-            "#{' '.concat(Process.pid.to_s) if @display_pid}] " \
-            "#{severity} -- : #{msg}\n"
+          now = Time.now
+          components = {
+            system: @system_name,
+            date: now.strftime('%Y-%m-%d'),
+            time: now.strftime('%H:%M:%S'),
+            correlation: @correlation_id,
+            pid: @display_pid ? Process.pid.to_s : nil,
+            level: severity,
+            separator: '-- :',
+          }
+
+          prefix = @prefix_colour.any? ? build_prefix_with_colour(components) : build_prefix(components)
+          "#{prefix}#{msg}\n"
         end
       end
 
     private
 
+      VALID_COLOUR_METHODS = %i[
+        white black red green brown yellow blue magenta cyan gray grey
+        bright_red bright_green bright_blue bright_magenta bright_cyan
+        bg_black bg_red bg_green bg_brown bg_yellow bg_blue bg_magenta bg_cyan bg_gray bg_grey bg_white
+        bg_bright_red bg_bright_green bg_bright_blue bg_bright_magenta bg_bright_cyan
+        bold dim italic underline reverse_colour reverse_color
+      ].freeze
+
+      VALID_PREFIX_KEYS = %i[system date time correlation pid level separator overall].freeze
+
+      def validate_colour_config
+        raise ArgumentError, 'Invalid prefix colour config' unless @prefix_colour.is_a?(Hash) && @prefix_colour.keys.all? { |key| VALID_PREFIX_KEYS.include?(key) }
+
+        @prefix_colour.each_value do |value|
+          raise ArgumentError, 'Colour values must be strings or symbols' unless valid_colour_type?(value)
+          raise ArgumentError, 'Invalid colours in prefix colour config' unless Array(value).map(&:to_sym).all? { |c| VALID_COLOUR_METHODS.include?(c) }
+        end
+      end
+
+      def valid_colour_type?(value)
+        value.is_a?(String) || value.is_a?(Symbol) || (value.is_a?(Array) && value.all? { |v| v.is_a?(String) || v.is_a?(Symbol) })
+      end
+
+      def apply_colours(text, colour_spec)
+        return text unless colour_spec
+
+        colour_spec.reduce(text) { |str, method| str.public_send(method) }
+      end
+
+      def build_prefix_with_colour(components)
+        system = apply_colours(components[:system], @prefix_colour[:system])
+        date = apply_colours(components[:date], @prefix_colour[:date])
+        time = apply_colours(components[:time], @prefix_colour[:time])
+        correlation = apply_colours(components[:correlation], @prefix_colour[:correlation])
+        pid = components[:pid] && apply_colours(components[:pid], @prefix_colour[:pid])
+        level = apply_colours(components[:level], @prefix_colour[:level])
+        separator = apply_colours(components[:separator], @prefix_colour[:separator])
+
+        bracket_content = [system, date, time, correlation, pid].compact.join(' ')
+        result = "[#{bracket_content}] #{level} #{separator} "
+        apply_colours(result, @prefix_colour[:overall]) || result
+      end
+
+      def build_prefix(components)
+        bracket_content = [components[:system], components[:date], components[:time], components[:correlation], components[:pid]].compact.join(' ')
+        "[#{bracket_content}] #{components[:level]} #{components[:separator]} "
+      end
+
       def set_proc_writer_scenario
         if @logdev.dev.is_a?(DVLA::Herodotus::MultiWriter) && @logdev.dev.targets.any?(DVLA::Herodotus::ProcWriter)
           proc_writers = @logdev.dev.targets.select { |t| t.is_a? DVLA::Herodotus::ProcWriter }

lib/dvla/herodotus/version.rb

@@ -1,5 +1,5 @@
 module DVLA
   module Herodotus
-    VERSION = '2.2.1'.freeze
+    VERSION = '2.3.0'.freeze
   end
 end

spec/dvla/herodotus/herodotus_logger_spec.rb

@@ -154,4 +154,136 @@
       expect(logger2.scenario_id).to eq('blah')
     end
   end
+
+  context 'prefix colourisation' do
+    before(:each) do
+      allow(Time).to receive(:now).and_return(Time.new(2022))
+      allow(SecureRandom).to receive(:uuid).and_return('123e4567-e89b-12d3-a456-426614174000')
+    end
+
+
+    it 'raises ArgumentError for invalid colour methods' do
+      expect {
+        config = DVLA::Herodotus.config do |c|
+          c.prefix_colour = {
+            system: %w[blue invalid_method],
+            level: %w[module_eval],
+          }
+        end
+        DVLA::Herodotus.logger('rspec', config: config)
+      }.to raise_error(ArgumentError, /Invalid colours in prefix colour config/)
+    end
+
+    it 'raises ArgumentError for invalid prefix option' do
+      expect {
+        config = DVLA::Herodotus.config do |c|
+          c.prefix_colour = {
+            unknown: %w[blue],
+          }
+        end
+        DVLA::Herodotus.logger('rspec', config: config)
+      }.to raise_error(ArgumentError, /Invalid prefix colour config/)
+    end
+
+    it 'raises ArgumentError for invalid prefix colour type' do
+      expect {
+        config = DVLA::Herodotus.config do |c|
+          c.prefix_colour = {
+            system: %r[blue],
+          }
+        end
+        DVLA::Herodotus.logger('rspec', config: config)
+      }.to raise_error(ArgumentError, /Colour values must be strings or symbols/)
+    end
+
+    it 'raises ArgumentError for invalid prefix colour' do
+      expect {
+        config = DVLA::Herodotus.config do |c|
+          c.prefix_colour = {
+            system: 'blellow',
+          }
+        end
+        DVLA::Herodotus.logger('rspec', config: config)
+      }.to raise_error(ArgumentError, /Invalid colours in prefix colour config/)
+    end
+
+    it 'accepts mixed format colour configuration' do
+      config = DVLA::Herodotus.config do |c|
+        c.prefix_colour = {
+          system: 'blue',
+          date: %w[green bold],
+          time: %i[yellow italic],
+          correlation: %w[magenta],
+          level: :red,
+          separator: %i[white dim],
+        }
+      end
+      expect { DVLA::Herodotus.logger('rspec', config: config)  }.to_not raise_error
+    end
+
+    it 'colours entire prefix with overall key' do
+      config = DVLA::Herodotus.config { |c| c.prefix_colour = { overall: %w[blue bold] } }
+      logger = DVLA::Herodotus.logger('rspec', config: config)
+
+      expect { logger.info('test') }.to output("\e[1m\e[34m[rspec 2022-01-01 00:00:00 123e4567] INFO -- : \e[39m\e[22mtest\n")
+                                          .to_stdout_from_any_process
+    end
+
+    it 'colours prefix individual components' do
+      config = DVLA::Herodotus.config do |c|
+        c.prefix_colour = {
+          system: %w[blue bold],
+          date: %w[green],
+          time: %w[yellow],
+          correlation: %w[magenta],
+          pid: %w[cyan],
+          level: %w[red bold],
+          separator: %w[white],
+        }
+      end
+      logger = DVLA::Herodotus.logger('rspec', config: config)
+
+      expected_output = "[\e[1m\e[34mrspec\e[39m\e[22m \e[32m2022-01-01\e[39m \e[93m00:00:00\e[39m \e[35m123e4567\e[39m] \e[1m\e[31mINFO\e[39m\e[22m \e[97m-- :\e[39m test\n"
+      expect { logger.info('test') }.to output(expected_output).to_stdout_from_any_process
+    end
+
+    it 'only colourises its own prefix' do
+      main_config = DVLA::Herodotus.config { |c| c.main = true }
+      main_logger = DVLA::Herodotus.logger('main', config: main_config)
+
+      secondary_config = DVLA::Herodotus.config { |c| c.prefix_colour = { overall: %w[red] } }
+      secondary_logger = DVLA::Herodotus.logger('secondary', config: secondary_config)
+
+      expect { main_logger.info('main test') }.to output("[main 2022-01-01 00:00:00 123e4567] INFO -- : main test\n")
+                                                    .to_stdout_from_any_process
+
+      expect { secondary_logger.info('secondary test') }.to output("\e[31m[secondary 2022-01-01 00:00:00 123e4567] INFO -- : \e[39msecondary test\n")
+                                                               .to_stdout_from_any_process
+    end
+
+    it 'ignores pid colour when display_pid is false' do
+      config = DVLA::Herodotus.config do |c|
+        c.display_pid = false
+        c.prefix_colour = { pid: %w[cyan] }
+      end
+      logger = DVLA::Herodotus.logger('rspec', config: config)
+
+      expect { logger.info('test') }.to output("[rspec 2022-01-01 00:00:00 123e4567] INFO -- : test\n")
+                                          .to_stdout_from_any_process
+    end
+
+    it 'allows partial colouring with optional keys' do
+      config = DVLA::Herodotus.config do |c|
+        c.prefix_colour = {
+          system: %w[blue bold],
+          level: %w[red],
+          # date, time, correlation, separator not specified
+        }
+      end
+      logger = DVLA::Herodotus.logger('rspec', config: config)
+
+      expected_output = "[\e[1m\e[34mrspec\e[39m\e[22m 2022-01-01 00:00:00 123e4567] \e[31mINFO\e[39m -- : test\n"
+      expect { logger.info('test') }.to output(expected_output).to_stdout_from_any_process
+    end
+  end
 end