"rails server" doesn't work. "Learn Rails" ebook chapter 12

Question

I'm reading the book "Learn Rails" and when I try to config the mailer with my Gmail account. I finished chapter 12, and tried to start the server application:

$ rails server

I got this error:

/Users/romenig/.rvm/rubies/ruby-2.0.0-p353/lib/ruby/2.0.0/psych.rb:205:in `parse': (<unknown>): mapping values are not allowed in this context at line 6 column 15 (Psych::SyntaxError)
    from /Users/romenig/.rvm/rubies/ruby-2.0.0-p353/lib/ruby/2.0.0/psych.rb:205:in `parse_stream'
    from /Users/romenig/.rvm/rubies/ruby-2.0.0-p353/lib/ruby/2.0.0/psych.rb:153:in `parse'
    from /Users/romenig/.rvm/rubies/ruby-2.0.0-p353/lib/ruby/2.0.0/psych.rb:129:in `load'
    from /Users/romenig/.rvm/gems/ruby-2.0.0-p353@learn-rails/gems/figaro-0.7.0/lib/figaro.rb:21:in `raw'
    from /Users/romenig/.rvm/gems/ruby-2.0.0-p353@learn-rails/gems/figaro-0.7.0/lib/figaro.rb:17:in `env'
    from /Users/romenig/.rvm/gems/ruby-2.0.0-p353@learn-rails/gems/figaro-0.7.0/lib/figaro/railtie.rb:7:in `block in <class:Railtie>'
    from /Users/romenig/.rvm/gems/ruby-2.0.0-p353@learn-rails/gems/activesupport-4.0.1/lib/active_support/lazy_load_hooks.rb:36:in `call'
    from /Users/romenig/.rvm/gems/ruby-2.0.0-p353@learn-rails/gems/activesupport-4.0.1/lib/active_support/lazy_load_hooks.rb:36:in `execute_hook'
    from /Users/romenig/.rvm/gems/ruby-2.0.0-p353@learn-rails/gems/activesupport-4.0.1/lib/active_support/lazy_load_hooks.rb:45:in `block in run_load_hooks'
    from /Users/romenig/.rvm/gems/ruby-2.0.0-p353@learn-rails/gems/activesupport-4.0.1/lib/active_support/lazy_load_hooks.rb:44:in `each'
    from /Users/romenig/.rvm/gems/ruby-2.0.0-p353@learn-rails/gems/activesupport-4.0.1/lib/active_support/lazy_load_hooks.rb:44:in `run_load_hooks'
    from /Users/romenig/.rvm/gems/ruby-2.0.0-p353@learn-rails/gems/railties-4.0.1/lib/rails/application.rb:67:in `inherited'
    from /Users/romenig/workspace_ror/learn-rails/config/application.rb:10:in `<module:LearnRails>'
    from /Users/romenig/workspace_ror/learn-rails/config/application.rb:9:in `<top (required)>'
    from /Users/romenig/.rvm/gems/ruby-2.0.0-p353@learn-rails/gems/railties-4.0.1/lib/rails/commands.rb:74:in `require'
    from /Users/romenig/.rvm/gems/ruby-2.0.0-p353@learn-rails/gems/railties-4.0.1/lib/rails/commands.rb:74:in `block in <top (required)>'
    from /Users/romenig/.rvm/gems/ruby-2.0.0-p353@learn-rails/gems/railties-4.0.1/lib/rails/commands.rb:71:in `tap'
    from /Users/romenig/.rvm/gems/ruby-2.0.0-p353@learn-rails/gems/railties-4.0.1/lib/rails/commands.rb:71:in `<top (required)>'
    from bin/rails:4:in `require'
    from bin/rails:4:in `<main>'

What do I need to do?

I searching StackOverflow's similar questions and I they recommended installing "libyaml":

$ rvm pkg install libyaml 

I got this message:

Beware, 'rvm pkg ...' is deprecated, read about the new autolibs feature: 'rvm help autolibs'.

Checking requirements for osx.
Updating certificates in '/opt/local/etc/openssl/cert.pem'.
romenig password required for 'mv -f /var/folders/y1/dgbv_pzd08bclqb3cnt_t0xw0000gn/T//tmp.ZRZBUpQ0BvThvcIhbV /opt/local/etc/openssl/cert.pem': 
Requirements installation successful.
Fetching yaml-0.1.4.tar.gz to /Users/romenig/.rvm/archives
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:--  0:00:01 --:--:--     0
curl: (22) The requested URL returned error: 404 Not Found
The requested url does not exist(22): 'https://rvm.io/src/yaml-0.1.4.tar.gz'
Checking fallback: ftp://rvm.io/src/yaml-0.1.4.tar.gz
Checking fallback: http://www.mirrorservice.org/sites/rvm.io/src/yaml-0.1.4.tar.gz
No fallback URL could be found, try increasing timeout with:

    echo "export rvm_max_time_flag=20" >> ~/.rvmrc


Please note that it's required to reinstall all rubies:

    rvm reinstall all --force

I did:

$ rvm reinstall all --force

When I did this I saw many errors:

ruby-1.9.2-head - #compiling..............................................................................................
Error running '__rvm_make -j 1',
please read /Users/romenig/.rvm/log/1386193970_ruby-1.9.2-head/make.log
There has been an error while running make. Halting the installation.
Removing /Users/romenig/.rvm/src/ruby-2.0.0-p353
Removing /Users/romenig/.rvm/rubies/ruby-2.0.0-p353.................
Error running '__rvm_rm_rf /Users/romenig/.rvm/rubies/ruby-2.0.0-p353',
please read /Users/romenig/.rvm/log/1386194140_ruby-2.0.0-p353/remove.rubies.log
Searching for binary rubies, this might take some time.
No binary rubies available for: osx/10.9/x86_64/ruby-2.0.0-p353.
Continuing with compilation. Please read 'rvm help mount' to get more information on binary rubies.
Checking requirements for osx.
Certificates in '/opt/local/etc/openssl/cert.pem' already are up to date.
Requirements installation successful.
Installing Ruby from source to: /Users/romenig/.rvm/rubies/ruby-2.0.0-p353, this may take a while depending on your cpu(s)...
ruby-2.0.0-p353 - #downloading ruby-2.0.0-p353, this may take a while depending on your connection...
ruby-2.0.0-p353 - #extracting ruby-2.0.0-p353 to /Users/romenig/.rvm/src/ruby-2.0.0-p353
ruby-2.0.0-p353 - #extracted to /Users/romenig/.rvm/src/ruby-2.0.0-p353
ruby-2.0.0-p353 - #configuring.......
.........
Error running '__rvm_rm_rf /Users/romenig/.rvm/rubies/ruby-2.0.0-p353',
please read /Users/romenig/.rvm/log/1386194140_ruby-2.0.0-p353/remove.rubies.log
Searching for binary rubies, this might take some time.
No binary rubies available for: osx/10.9/x86_64/ruby-2.0.0-p353.
Continuing with compilation. Please read 'rvm help mount' to get more information on binary rubies.
Checking requirements for osx.
Certificates in '/opt/local/etc/openssl/cert.pem' already are up to date.
Requirements installation successful.
Installing Ruby from source to: /Users/romenig/.rvm/rubies/ruby-2.0.0-p353, this may take a while depending on your cpu(s)...
ruby-2.0.0-p353 - #downloading ruby-2.0.0-p353, this may take a while depending on your connection...
ruby-2.0.0-p353 - #extracting ruby-2.0.0-p353 to /Users/romenig/.rvm/src/ruby-2.0.0-p353
ruby-2.0.0-p353 - #extracted to /Users/romenig/.rvm/src/ruby-2.0.0-p353
ruby-2.0.0-p353 - #configuring.......

I tried to start the Rails server again:

$ rails server

And got:

Rails is not currently installed on this system. To get the latest version, simply type:

$ sudo gem install rails

I installed Rails again and have the same error.

Answer 1

The cause of the error for me was that the following line in application.yml was split in to two, and outside the commented scope-

#Each entry sets a local environment variable and overrides ENV variables in the Unix
shell.

Answer 2

First of all, reinstalling all of your Rubies nuked your installed gems; but those are easy enough to get back.

cd into your project directory and run:

gem install bundler
bundle install

From the original error message:

mapping values are not allowed in this context at line 6 column 15 (Psych::SyntaxError)

It looks like there's a problem with the syntax in a YAML file. From the stack trace, it looks like it's coming from Figaro, so double-check your config/application.yml file.