did everything according to the instructions
alexey@mx:/var/www/html/redmine$ sudo bundle exec rake redmine:plugins NAME=redmine_agile RAILS_ENV=production (in /usr/share/redmine) rake aborted! Gem::LoadError: Specified 'mysql2' for database adapter, but the gem is not loaded. Add `gem 'mysql2'` to your Gemfile (and ensure its version is at the minimum required by ActiveRecord). gemfile
seen_adapters = {} Dir['{config,instances/*/config}/database.yml'].select do |f| File.exists?(f) end.each do |database_file| database_config = YAML::load(ERB.new(IO.read(database_file)).result) adapters = database_config.values.map {|c| c['adapter']}.compact.uniq if adapters.any? adapters.each do |adapter| next if seen_adapters[adapter] seen_adapters[adapter] = true case adapter when 'mysql2' gem "mysql2", "~> 0.4.0", :platforms => [:mri, :mingw, :x64_mingw] gem "activerecord-jdbcmysql-adapter", :platforms => :jruby when 'mysql' gem "activerecord-jdbcmysql-adapter", :platforms => :jruby when /postgresql/ gem "pg", "~> 0.18.1", :platforms => [:mri, :mingw, :x64_mingw] gem "activerecord-jdbcpostgresql-adapter", :platforms => :jruby when /sqlite3/ gem "sqlite3", :platforms => [:mri, :mingw, :x64_mingw] gem "jdbc-sqlite3", ">= 3.8.10.1", :platforms => :jruby gem "activerecord-jdbcsqlite3-adapter", :platforms => :jruby when /sqlserver/ gem "tiny_tds", "~> 0.6.2", :platforms => [:mri, :mingw, :x64_mingw] gem "activerecord-sqlserver-adapter", :platforms => [:mri, :mingw, :x64_mingw] else warn("Unknown database adapter `#{adapter}` found in config/database.yml, use Gemfile.local to load your own database gems") end end else warn("No adapter found in config/database.yml, please configure it first") end end sudo gem install mysql2
Building native extensions. This could take a while... ERROR: Error installing mysql2: ERROR: Failed to build gem native extension. current directory: /var/lib/gems/2.3.0/gems/mysql2-0.4.5/ext/mysql2 /usr/bin/ruby2.3 -r ./siteconf20170212-3499-mqg2bh.rb extconf.rb mkmf.rb can't find header files for ruby at /usr/lib/ruby/include/ruby.h extconf failed, exit code 1 Gem files will remain installed in /var/lib/gems/2.3.0/gems/mysql2-0.4.5 for inspection. Results logged to /var/lib/gems/2.3.0/extensions/x86_64-linux/2.3.0/mysql2-0.4.5/gem_make.out 