Nginx routing with Docker Rails 5 Postgres app - postgresql

Question

When I tried to Dockerize Rails app into container and run Nginx on host I got problem with routing from outside in.
I can't access /public in rails app container. Instead I can see /var/www/app/public at host.
How can I route from Nginx to Docker Rails container?
nginx.conf:
upstream puma_app {
server 127.0.0.1:3000;
}
server {
listen 80;
client_max_body_size 4G;
keepalive_timeout 10;
error_page 500 502 504 /500.html;
error_page 503 #503;
server_name localhost app;
root /var/www/app/public;
try_files $uri/index.html $uri #puma_app;
location #puma_app {
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Host $http_host;
proxy_redirect off;
proxy_pass http://puma_app;
# limit_req zone=one;
access_log /var/log/nginx/access.log;
error_log /var/log/nginx/error.log;
}
location ^~ /assets/ {
gzip_static on;
expires max;
add_header Cache-Control public;
}
location = /50x.html {
root html;
}
location = /404.html {
root html;
}
location #503 {
error_page 405 = /system/maintenance.html;
if (-f $document_root/system/maintenance.html) {
rewrite ^(.*)$ /system/maintenance.html break;
}
rewrite ^(.*)$ /503.html break;
}
if ($request_method !~ ^(GET|HEAD|PUT|PATCH|POST|DELETE|OPTIONS)$ ){
return 405;
}
if (-f $document_root/system/maintenance.html) {
return 503;
}
location ~ \.(php|html)$ {
return 405;
}
}
docker-compose.yml:
version: '2'
services:
app:
build: .
command: bundle exec puma -C config/puma.rb
volumes:
- 'app:/var/www/app'
- 'public:/var/www/app/public'
ports:
- '3000:3000'
depends_on:
- postgres
env_file:
- '.env'
postgres:
image: postgres:latest
environment:
POSTGRES_USER: 'postgres_user'
ports:
- '5432:5432'
volumes:
- 'postgres:/var/lib/postgresql/data'
volumes:
postgres:
app:
public:
Dockerfile
# Base image:
FROM ruby:2.4
# Install dependencies
RUN apt-get update -qq && apt-get install -y build-essential libpq-dev nodejs
# Set an environment variable where the Rails app is installed to inside of Docker image:
ENV RAILS_ROOT /var/www/app
RUN mkdir -p $RAILS_ROOT
ENV RAILS_ENV production
ENV RACK_ENV production
# Set working directory, where the commands will be ran:
WORKDIR $RAILS_ROOT
# Gems:
COPY Gemfile Gemfile
COPY Gemfile.lock Gemfile.lock
RUN gem install bundler
RUN bundle install
COPY config/puma.rb config/puma.rb
# Copy the main application.
COPY . .
RUN bundle exec rake RAILS_ENV=production assets:precompile
VOLUME ["$RAILS_ROOT/public"]
EXPOSE 3000
# The default command that gets ran will be to start the Puma server.
CMD bundle exec puma -C config/puma.rb

Answer 1

I think you are trying to access /public from host inside the container at /var/www/app/public.
You need to mount host directory inside container. You can use -v "/public:/var/www/app/public" while running the container.

Answer 2

There are some issues with your Dockerfile. I'm not sure how you want to setup your docker image, but it seem like you try to use a public directory in a docker volume; I would suggest to store the compiled assets into the docker image itself. This way, you can sure that the assets are always together with the image.
You current Dockerfile should run the assets:precompile before the COPY . .; Meaning the assets should be compiled into the public directory first before copying it into the docker image.
Anyhow, you should try a running a really simple docker app first before using it on a more complex project setup, here's a blog post that might help you (disclaimer: I wrote that post)

Answer 3

In docker, every container has it's own IP address and are not local to each other. So you can't use 127.0.0.1 ip in the Nginx container as ip of the Rails container. Fortunately docker containers can be linked together using their service names. So you must replace change your upstream to
upstream puma_app {
server http://app:3000;
}
Also you should add Nginx container to your docker-compose file (suppose your nginx conf files are in config/nginx/conf.d dir):
version: '2'
services:
app:
build: .
command: bundle exec puma -C config/puma.rb
volumes:
- app:/var/www/app
- public:/var/www/app/public
- nginx-confs:/var/www/app/config/nginx/conf.d
ports:
- 3000:3000
depends_on:
- postgres
env_file: .env
postgres:
image: postgres:latest
environment:
- POSTGRES_USER=postgres_user
ports:
- 5432:5432
volumes:
- postgres:/var/lib/postgresql/data
nginx:
image: nginx:latest
ports:
- 80:80
- 443:443
volumes:
- nginx-confs:/etc/nginx/conf.d
volumes:
postgres:
app:
public:
nginx-confs: