Rails app works in ElasticBeanstalk but not in Docker Passenger container

Question

I have a Rails app that works fine in ElasticBeanstalk. I am now trying to run in in the Docker Phusion Passenger Container.

My Dockerfile is pretty simple:

FROM phusion/passenger-ruby21:0.9.13

# Set correct environment variables.
ENV HOME /root

# Use baseimage-docker's init process.
CMD ["/sbin/my_init"]

RUN rm -f /etc/service/nginx/down
RUN rm /etc/nginx/sites-enabled/default
ADD webapp.conf /etc/nginx/sites-enabled/webapp.conf
#Preserver Env Vars set at run time
ADD passenger-envvars.conf /etc/nginx/main.d/passenger-envvars.conf

ENV APP_HOME /home/app/webapp/
RUN mkdir $APP_HOME

WORKDIR /tmp
ADD Gemfile /tmp/
ADD Gemfile.lock /tmp/
RUN bundle install

ADD . $APP_HOME

When I run the container, Passenger gives me the following error:

undefined method `[]' for nil:NilClass (NoMethodError)
   /home/app/webapp/config/environment.rb:11:in `<top (required)>'
   config.ru:3:in `require'
   config.ru:3:in `block in <main>'
   /var/lib/gems/2.1.0/gems/rack-1.5.5/lib/rack/builder.rb:55:in     `instance_eval'
  /var/lib/gems/2.1.0/gems/rack-1.5.5/lib/rack/builder.rb:55:in `initialize'
  config.ru:1:in `new'
  config.ru:1:in `<main>'
  /usr/share/passenger/helper-scripts/rack-preloader.rb:112:in `eval'
  /usr/share/passenger/helper-scripts/rack-preloader.rb:112:in `preload_app'
  /usr/share/passenger/helper-scripts/rack-preloader.rb:158:in `<module:App>'
  /usr/share/passenger/helper-scripts/rack-preloader.rb:29:in `<module:PhusionPassenger>'
  /usr/share/passenger/helper-scripts/rack-preloader.rb:28:in `<main>'

My environment.rb file is:

require File.expand_path('../application', __FILE__)

if ENV['C_ENVIRONMENT']
  %w(RACK_ENV RAILS_ENV).each do |key|
    ENV[key] = ENV['C_ENVIRONMENT']
  end
  Rails.env = ENV['C_ENVIRONMENT'] if defined?(Rails)
end

CONFIG = YAML.load(ERB.new(File.read("config/config.yml")).result)[Rails.env]
T_CONFIG = CONFIG["tableau"]
CM_CONFIG = CONFIG["customer_metadata"]
LDAP_CONFIG = CONFIG["ldap"]

# Initialize the rails application
Ecommerce::Application.initialize!

I've confirmed that NGinx is preserving all the Environment Variables that I need. The difficultly seems to be with this line (line 11):

CONFIG = YAML.load(ERB.new(File.read("config/config.yml")).result)[Rails.env]

The config/config.yml file exists, and had the necessary config to match the RAILS_ENV variable that is being passed to it.

My suspicion is that the Docker container is having difficultly reading a file into memory, perhaps due to the way bundle install is being run as root, and is not creating the necessary CONFIG object for Rails to read.

I am not a Ruby developer (I'm Operations), so please forgive any absence of basic Ruby knowledge.

Answer 1

As usual, 5 minutes later I figure it out.

My Docker run time command is:

docker run -p "8888:80" -it --name myapp-passenger --env-file ./envvars myapp-passenger

The envvars file contains my environment variables. I had been double-quoting these eg

C_ENVIRONMENT="integration"

Instead, they should just be:

C_ENVIRONMENT=integration