ci: add config linter

Author: G-Rath

ci/bin/build-and-test

@@ -4,6 +4,8 @@ require "fileutils"
 require "pathname"
 require "yaml"
 
+require_relative "lint-configs"
+
 def ensure_everything_is_committed
   out = `git status -s`
 
@@ -31,7 +33,7 @@ config_path = if ENV.fetch("CONFIG_PATH", "") == ""
               end
 
 config_env_var = %Q(CONFIG_PATH="#{config_path}") if config_path
-skip_flags = ENV.fetch("SKIPS", "--skip-javascript --skip-docker --skip-kamal --skip-solid")
+skip_flags = ENV.fetch("SKIPS", "--skip-javascript --skip-docker")
 
 puts "=" * 80
 puts <<~EO_CONFIG_SUMMARY
@@ -90,6 +92,9 @@ Dir.chdir(app_path) do |cwd|
   puts "Checking everything is committed and there are no un-staged files"
   ensure_everything_is_committed
 
+  puts "Checking that no config properties have been duplicated in environment files"
+  ensure_no_duplicate_config_lines_in_environment_files
+
   puts "Running test suite"
   system("./bin/ci-run", exception: true)
 end

ci/bin/lint-configs.rb

@@ -0,0 +1,57 @@
+#!/usr/bin/env ruby
+
+# Checks the given file for repeated "config.xyz = " lines
+#
+# @param [String] file
+#
+# @return [Array<String>]
+def check_file_for_repeated_config_properties(file)
+  # @type [Array<String>]
+  seen = []
+  # @type [Array<String>]
+  duplicates = []
+  in_condition = false
+
+  File.readlines(file).each do |line|
+    in_condition = true if line.strip.start_with?("if")
+    in_condition = false if line.strip == "end"
+
+    # ignore conditions for now
+    next if in_condition
+
+    line.match(/(config\.[a-zA-Z_]+) = /) do |match|
+      duplicates << match[1] if seen.include?(match[1])
+
+      seen << match[1]
+    end
+  end
+
+  duplicates
+end
+
+# Checks each environment config file for duplicate config properties,
+# as we should be reusing lines where possible to avoid confusion
+# and reduce the diff when doing Rails upgrades on applications
+def ensure_no_duplicate_config_lines_in_environment_files
+  # @type [Hash<String, Array<String>>]
+  results = {}
+
+  Dir.glob("**/config/environments/*.rb").each do |file|
+    results[file] = check_file_for_repeated_config_properties(file)
+  end
+
+  results.reject! { |_, duplicates| duplicates.empty? }
+
+  results.each do |file, duplicates|
+    puts "#{file} has duplicate config properties:"
+    duplicates.each { |line| puts "  - #{line}" }
+  end
+
+  raise "one or more environment files had duplicate configs" unless results.empty?
+end
+
+if __FILE__ == $PROGRAM_NAME
+  Dir.chdir(ARGV[0]) do
+    ensure_no_duplicate_config_lines_in_environment_files
+  end
+end