How to access dockerized rails server using "localhost" - ruby-on-rails

Question

I don't play often with Docker so I'm really confused here.
Here is my Dockerfile:
ARG RUBY_VERSION
FROM ruby:${RUBY_VERSION}-slim-buster
ARG PG_MAJOR
ARG NODE_MAJOR
ARG BUNDLER_VERSION
ARG YARN_VERSION
# common dependencies
RUN apt-get update -qq \
&& DEBIAN_FRONTEND=noninteractive apt-get install -yq --no-install-recommends \
build-essential \
gnupg2 \
curl \
less \
git \
&& apt-get clean \
&& rm -fr /var/cache/apt/archives/* \
&& rm -fr /var/lib/apt/lists/* /tmp/* /var/tmp/* \
&& truncate -s 0 /var/log/*log
# add postgresql to sources list
RUN curl -sSL https://www.postgresql.org/media/keys/ACCC4CF8.asc | apt-key add - \
&& echo 'deb http://apt.postgresql.org/pub/repos/apt/ buster-pgdg main' $PG_MAJOR > /etc/apt/sources.list.d/pgdg.list
# add nodejs to sources list
RUN curl -sL https://deb.nodesource.com/setup_$NODE_MAJOR.x | bash -
# add yarn to sources list
RUN curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add - \
&& echo 'deb http://dl.yarnpkg.com/debian/ stable main' > /etc/apt/sources.list.d/yarn.list
# application dependencies
# we use an external aptfile for that
COPY Aptfile /tmp/Aptfile
RUN apt-get update -qq && DEBIAN_FRONTEND=noninteractive apt-get -yq dist-upgrade && \
DEBIAN_FRONTEND=noninteractive apt-get install -yq --no-install-recommends \
libpq-dev \
postgresql-client-$PG_MAJOR \
nodejs \
yarn=$YARN_VERSION-1 \
$(cat /tmp/Aptfile | xargs) && \
apt-get clean && \
rm -fr /var/lib/apt/lists/* /tmp/* /var/tmp/* && \
truncate -s 0 /var/log/*log
# configure bundler
ENV LANG=C.UTF-8 \
BUNDLE_JOBS=4 \
BUNDLE_RETRY=3
# upgrade rubygems and install required bundler version
RUN gem update --system && \
gem install bundler:${BUNDLER_VERSION}
# create a directory for the app code
RUN mkdir -p /app
WORKDIR /app
And here is my docker-compose.yml:
version: '3.8'
services:
app: &app
build:
context: .dockerdev
dockerfile: Dockerfile
args:
BUNDLER_VERSION: '2.1.4'
NODE_MAJOR: '11'
PG_MAJOR: '13'
RUBY_VERSION: '2.7.2'
YARN_VERSION: '1.22.5'
image: example-dev:1.0.0
tmpfs:
- /tmp
backend: &backend
<<: *app
stdin_open: true
tty: true
volumes:
- .:/app:cached
- rails_cache:/app/tmp/cache
- bundle:/usr/local/bundle
- node_modules:/app/node_modules
- packs:/app/public/packs
- .dockerdev/.psqlrc:/root/.psqlrc:ro
environment:
- NODE_ENV=development
- RAILS_ENV=${RAILS_ENV:-development}
- REDIS_URL=redis://redis:6379/
- DATABASE_URL=postgres://postgres:postgres#postgres:5432
- BOOTSNAP_CACHE_DIR=/usr/local/bundle/_bootsnap
- WEBPACKER_DEV_SERVER_HOST=webpacker
- HISTFILE=/app/log/.bash_history
- PSQL_HISTFILE=/app/log/.psql_history
- EDITOR=vi
- MALLOC_ARENA_MAX=2
- WEB_CONCURRENCY=${WEB_CONCURRENCY:-1}
depends_on:
postgres:
condition: service_healthy
redis:
condition: service_healthy
runner:
<<: *backend
command: /bin/bash
ports:
- '3000:3000'
- '3002:3002'
rails:
<<: *backend
command: bundle exec rails server -b 0.0.0.0
ports:
- '3000:3000'
sidekiq:
<<: *backend
command: bundle exec sidekiq -C configs/sidekiq.yml
postgres:
image: postgres:13.1
volumes:
- .psqlrc:/root/.psqlrc:ro
- postgres:/var/lib/postgresql/data
- ./log:/root/log:cached
- ./.dockerdev/init.sql:/docker-entrypoint-initdb.d/init.sql
environment:
- PSQL_HISTFILE=/root/log/.psql_history
- POSTGRES_PASSWORD=postgres
ports:
- 5432
healthcheck:
test: pg_isready -U postgres -h 127.0.0.1
interval: 5s
redis:
image: redis:5.0-alpine
volumes:
- redis:/data
ports:
- 6379
healthcheck:
test: redis-cli ping
interval: 1s
timeout: 3s
retries: 30
webpacker:
<<: *app
command: ./bin/webpack-dev-server
ports:
- '3035:3035'
volumes:
- .:/app:cached
- bundle:/usr/local/bundle
- node_modules:/app/node_modules
- packs:/app/public/packs
environment:
- NODE_ENV=${NODE_ENV:-development}
- RAILS_ENV={RAILS_ENV:-development}
- WEBPACKER_DEV_SERVER_HOST=0.0.0.0
volumes:
postgres:
redis:
bundle:
node_modules:
rails_cache:
packs:
Everything works just fine, I can run my runner, install gems, play with db, run rails, etc.
Until I try to reach http://localhost:3000 which only shows:
This site can’t be reached
localhost refused to connect.
Here is the step I do to run rails server:
$ docker-compose run --rm rails
Creating okamii-saas_rails_run ... done
=> Booting Puma
=> Rails 6.0.3.4 application starting in development
=> Run `rails server --help` for more startup options
Puma starting in single mode...
* Version 4.3.6 (ruby 2.7.2-p137), codename: Mysterious Traveller
* Min threads: 5, max threads: 5
* Environment: development
* Listening on tcp://0.0.0.0:3000
Use Ctrl-C to stop
And here is the result of docker-compose ps:
Name Command State Ports
------------------------------------------------------------------------------------------------------------
okamii-saas_postgres_1 docker-entrypoint.sh postgres Up (healthy) 0.0.0.0:32789->5432/tcp
okamii-saas_rails_run_6fff67202995 bundle exec rails server - ... Up
okamii-saas_redis_1 docker-entrypoint.sh redis ... Up (healthy) 0.0.0.0:32788->6379/tcp
I have the feeling that the fact that nothing shows in the Ports column for okamii-saas_rails_run_6fff67202995 is a sign something is wrong but I don't know why it is empty and what I am supposed to do here. (cf. EDIT 1)
As a note, I know the title say how to using localhost but I really can't access it at all AFAIK :)
===
EDIT 1:
That's not entirely true. I figured that by adding EXPOSE 3000 in my Dockerfile, docker-compose ps will show something in the column Ports for my container but that did not change things a bit.
Here is an updated view of docker-composer ps when using EXPOSE 3000:
Name Command State Ports
------------------------------------------------------------------------------------------------------------
okamii-paas_postgres_1 docker-entrypoint.sh postgres Up (healthy) 0.0.0.0:32771->5432/tcp
okamii-paas_rails_run_d812907346b4 bundle exec rails server - ... Up 3000/tcp
okamii-paas_redis_1 docker-entrypoint.sh redis ... Up (healthy) 0.0.0.0:32770->6379/tcp
EDIT 2:
From what I can read from the doc about EXPOSE, it is only acting as a documentation. It does not do anything else which explains why using it does not change anything.
EDIT 3:
I just tried running docker-compose up -d rails instead of docker-compose run rails and this message started spawning:
$ dc up -d rails
Creating network "okamii-paas_default" with the default driver
Creating okamii-paas_postgres_1 ... done
Creating okamii-paas_redis_1 ... done
Creating okamii-paas_rails_1 ...
Creating okamii-paas_rails_1 ... error
ERROR: for okamii-paas_rails_1 Cannot start service rails: driver failed programming external connectivity on endpoint okamii-paas_rails_1 (5d07dfedfc5c979133ce61a237327edb149a0a6793a85f61f6ad8218a60a510b): Bind for 0.0.0.0:3000 failed: port is already allocated
ERROR: for rails Cannot start service rails: driver failed programming external connectivity on endpoint okamii-paas_rails_1 (5d07dfedfc5c979133ce61a237327edb149a0a6793a85f61f6ad8218a60a510b): Bind for 0.0.0.0:3000 failed: port is already allocated
ERROR: Encountered errors while bringing up the project.
I don't understand where the conflict comes from.
After #dbugger's suggestion, I tweaked the ports publication from "3000:3000" to "3000". And now, stuff shows in the Ports column but of course, the mapping is wrong.
Name Command State Ports
------------------------------------------------------------------------------------------------
okamii-paas_postgres_1 docker-entrypoint.sh postgres Up (healthy) 0.0.0.0:32784->5432/tcp
okamii-paas_rails_1 bundle exec rails server - ... Up 0.0.0.0:32786->3000/tcp
okamii-paas_redis_1 docker-entrypoint.sh redis ... Up (healthy) 0.0.0.0:32785->6379/tcp