问题
I have a rails 4 project that has been working for some time. I attempted to install taps but got an error message:
$ gem install taps
/usr/local/rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/psych.rb:370:in `parse': (<unknown>): mapping values are not allowed in this context at line 2 column 29 (Psych::SyntaxError)
from /usr/local/rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/psych.rb:370:in `parse_stream'
from /usr/local/rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/psych.rb:318:in `parse'
from /usr/local/rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/psych.rb:245:in `load'
from /usr/local/rvm/rubies/ruby-2.2.1/lib/ruby/site_ruby/2.2.0/rubygems/config_file.rb:333:in `load_file'
from /usr/local/rvm/rubies/ruby-2.2.1/lib/ruby/site_ruby/2.2.0/rubygems/config_file.rb:198:in `initialize'
from /usr/local/rvm/rubies/ruby-2.2.1/lib/ruby/site_ruby/2.2.0/rubygems/gem_runner.rb:74:in `new'
from /usr/local/rvm/rubies/ruby-2.2.1/lib/ruby/site_ruby/2.2.0/rubygems/gem_runner.rb:74:in `do_configuration'
from /usr/local/rvm/rubies/ruby-2.2.1/lib/ruby/site_ruby/2.2.0/rubygems/gem_runner.rb:39:in `run'
from /usr/local/rvm/rubies/ruby-2.2.1/bin/gem:21:in `<main>'
I get the same error message when trying to run gem list or bundle update. I searched for similar problems, and it seems the cause is typically an improperly formatted YAML file. My database.yml file and Gemfile were not recently updated, so I don't know when this bug was introduced.
I found a rails issue on Github that describes this error, and someone recommended parsing YAML files with irb to isolate the issue. I tried parsing database.yml and Gemfile:
config/database.yml
# SQLite version 3.x
# gem install sqlite3
#
# Ensure the SQLite 3 gem is defined in your Gemfile
# gem 'sqlite3'
#
default: &default
adapter: sqlite3
pool: 5
timeout: 5000
development:
<<: *default
database: db/development.sqlite3
# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
test:
<<: *default
database: db/test.sqlite3
production:
<<: *default
database: db/production.sqlite3
$ irb -ryaml
2.2.1 :001 > YAML.load_file 'config/database.yml'
=> {"default"=>{"adapter"=>"sqlite3", "pool"=>5, "timeout"=>5000}, "development"=>{"adapter"=>"sqlite3", "pool"=>5, "timeout"=>5000, "database"=>"db/development.sqlite3"}, "test"=>{"adapter"=>"sqlite3", "pool"=>5, "timeout"=>5000, "database"=>"db/test.sqlite3"}, "production"=>{"adapter"=>"sqlite3", "pool"=>5, "timeout"=>5000, "database"=>"db/production.sqlite3"}}
Gemfile
source 'https://rubygems.org'
gem 'rails', '4.2.2'
gem 'faker', '1.4.2'
gem 'will_paginate', '3.0.7'
gem 'bootstrap-will_paginate', '0.0.10'
gem 'bootstrap-sass', '3.2.0.0'
gem 'sass-rails', '5.0.2'
gem 'uglifier', '2.5.3'
gem 'coffee-rails', '4.1.0'
gem 'jquery-rails', '4.0.3'
gem 'turbolinks', '2.3.0'
gem 'jbuilder', '2.2.3'
gem 'devise', '3.5.6'
group :development, :test do
gem 'sqlite3', '1.3.9'
gem 'byebug', '3.4.0'
gem 'web-console', '2.0.0.beta3'
gem 'spring', '1.1.3'
end
group :test do
gem 'minitest-reporters', '1.0.5'
gem 'mini_backtrace', '0.1.3'
gem 'guard-minitest', '2.3.1'
end
group :production do
gem 'pg', '0.17.1'
gem 'rails_12factor', '0.0.2'
end
$ irb -ryaml
2.2.1 :001 > YAML.load_file 'Gemfile'
=> "source 'https://rubygems.org'\n\ngem 'rails', '4.2.2' gem 'faker', '1.4.2' gem 'will_paginate', '3.0.7' gem 'bootstrap-will_paginate', '0.0.10' gem 'bootstrap-sass', '3.2.0.0' gem 'sass-rails', '5.0.2' gem 'uglifier', '2.5.3' gem 'coffee-rails', '4.1.0' gem 'jquery-rails', '4.0.3' gem 'turbolinks', '2.3.0' gem 'jbuilder', '2.2.3' gem 'devise', '3.5.6'\ngroup :development, :test do gem 'sqlite3', '1.3.9' gem 'byebug', '3.4.0' gem 'web-console', '2.0.0.beta3' gem 'spring', '1.1.3' end\ngroup :test do gem 'minitest-reporters', '1.0.5' gem 'mini_backtrace', '0.1.3' gem 'guard-minitest', '2.3.1' end\ngroup :production do gem 'pg', '0.17.1' gem 'rails_12factor', '0.0.2' end"
Both files parse correctly, so I am stuck. I don't know why the commands keep failing since the error message doesn't identify the offending file.
回答1:
I was finally able to track down the source of this error.
rubygems/config_file.rb:
SYSTEM_WIDE_CONFIG_FILE = File.join SYSTEM_CONFIG_PATH, 'gemrc'
...
system_config = load_file SYSTEM_WIDE_CONFIG_FILE
I tried parsing my .gemrc file and it failed:
$ irb -ryaml
2.2.1 :001 > YAML.load_file '/home/ubuntu/.gemrc'
Psych::SyntaxError: (/home/ubuntu/.gemrc): mapping values are not allowed in this context at line 2 column 29
from /usr/local/rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/psych.rb:370:in `parse'
from /usr/local/rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/psych.rb:370:in `parse_stream'
from /usr/local/rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/psych.rb:318:in `parse'
from /usr/local/rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/psych.rb:245:in `load'
from /usr/local/rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/psych.rb:464:in `block in load_file'
from /usr/local/rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/psych.rb:464:in `open'
from /usr/local/rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/psych.rb:464:in `load_file'
from (irb):1
from /usr/local/rvm/rubies/ruby-2.2.1/bin/irb:11:in `<main>'
Somehow, two lines became joined in my ~/.gemrc:
install: --no-rdoc --no-ri
update: --no-rdoc --no-rigem: --no-rdoc --no-ri
Separating them back out resolved the problem:
install: --no-rdoc --no-ri
update: --no-rdoc --no-ri
gem: --no-rdoc --no-ri
Since my .gemrc file is not under my project's revision control, I was seeing the error no matter which historical commit I checked out.
来源：https://stackoverflow.com/questions/35920892/bundle-install-results-in-mapping-values-are-not-allowed-in-this-context-error