Rails docker postgres Connection refused - ruby-on-rails

Question

I'm trying to dockerize my Rails application, but I have this error when I want to run it with docker-compose:
! Unable to load application: PG::ConnectionBad: could not connect to server: Connection refused
Is the server running on host "postgres" (127.0.0.1) and accepting
TCP/IP connections on port 5432?
my docker-compose file is:
version: '2'
services:
web:
build: .
image: cda_app
container_name: "cda_app_web"
ports:
- '127.0.0.1:${WEB_PORT}:3000'
env_file: .env
volumes:
- gems:/gems
- ./:/var/www/app
logging:
driver: 'json-file'
options:
max-size: '100m'
max-file: '5'
links:
- redis
- postgres
entrypoint: 'bundle exec puma -C config/puma.rb'
redis:
image: 'redis'
volumes:
- redis:/data
- redis_log:/var/log/redis
postgres:
image: 'postgres:12.4'
volumes:
- postgres:/var/lib/postgresql/data
- postgres_log:/var/log/postgresql
volumes:
gems:
redis:
redis_log:
postgres:
postgres_log:
Dockerfile:
ARG BASE_IMAGE=ruby:2.7.1
FROM $BASE_IMAGE
RUN apt-get update && \
apt-get install -y \
apt-utils \
build-essential \
cmake \
curl \
ghostscript \
libmagic-dev \
libpq-dev \
openssh-client \
rename \
&& rm -rf /var/lib/apt/lists/*
RUN curl -sL https://deb.nodesource.com/setup_12.x | bash && apt-get install -y nodejs
RUN npm install -g yarn
WORKDIR /var/www/app
RUN mkdir /gems
ENV BUNDLE_PATH=/gems
RUN gem install bundler
ARG BUNDLE_WITHOUT=development:test
COPY Gemfile Gemfile.lock ./
RUN bundle install --jobs $(nproc) --with BUNDLE_WITHOUT
COPY package.json yarn.lock ./
RUN yarn install --check-files --ignore-optional
COPY . .
RUN rename -f -v 's/\.sample//' config/*sample.yml
EXPOSE 3000
CMD ./bin/puma -b tcp://0.0.0.0:3000
my database.yml:
default: &default
pool: <%= ENV["DB_POOL"] %>
template: 'template0'
adapter: 'postgresql'
database: <%= ENV["DB_NAME"] %>
username: <%= ENV["DB_USER"] %>
host: <%= ENV["DB_HOST"] %>
port: <%= ENV["DB_PORT"] %>
password: <%= ENV["DB_PASSWORD"] %>
timeout: 5000
encoding: 'utf8'
min_messages: WARNING
development:
<<: *default
database: <%= ENV["DB_NAME"] %>_development
test:
<<: *default
database: <%= ENV["DB_NAME"] %>_test<%= ENV['TEST_ENV_NUMBER'] %>
production:
<<: *default
database: <%= ENV["DB_NAME"] %>_production
.env file:
DB_NAME=cda_database
DB_HOST=postgres
DB_USER=postgres
DB_PASSWORD=postgres
DB_PORT=5432
DB_POOL=5
I can't understand what I'm doing wrong?!
It seems I did everything correctly, but I'm getting the error.
I'm using Digitalocean. Also, the database is working outside of docker, but it can't be accessible in docker.

Answer 1

You can try it in docker-compose file. I hope it working
postgres:
image: 'postgres:12.4'
volumes:
- postgres:/var/lib/postgresql/data
- postgres_log:/var/log/postgresql
environment:
- POSTGRES_USER= postgres
- POSTGRES_PASSWORD= postgres

Answer 2

You can write the environment variables each one for postgresql in docker-compose.yml, example:
version: '2'
services:
web:
build: .
image: cda_app
container_name: "cda_app_web"
ports:
- '127.0.0.1:${WEB_PORT}:3000'
env_file: .env
volumes:
- gems:/gems
- ./:/var/www/app
logging:
driver: 'json-file'
options:
max-size: '100m'
max-file: '5'
links:
- redis
- postgres
entrypoint: 'bundle exec puma -C config/puma.rb'
redis:
image: 'redis'
volumes:
- redis:/data
- redis_log:/var/log/redis
postgres:
image: 'postgres:12.4'
volumes:
- postgres:/var/lib/postgresql/data
- postgres_log:/var/log/postgresql
environment:
POSTGRES_PASSWORD: "${DB_PASSWORD}"
POSTGRES_USER: "${DB_USER}"
POSTGRES_DB: "${DB_NAME}"
volumes:
gems:
redis:
redis_log:
postgres:
postgres_log:
Be aware that the file .env must be in the same directory than your docker-compose.yml