Docker: Is the server running on host "localhost" (::1) and accepting TCP/IP connections on port 5432?

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I am getting issues while setup and run the docker instance on my local system with Ruby on Rail. Please see my docker configuration files:-

Dockerfile

FROM ruby:2.3.1

RUN useradd -ms /bin/bash web
RUN apt-get update -qq && apt-get install -y build-essential
RUN apt-get -y install nginx
RUN apt-get -y install sudo
# for postgres
RUN apt-get install -y libpq-dev

# for nokogiri
RUN apt-get install -y libxml2-dev libxslt1-dev

# for a JS runtime
RUN apt-get install -y nodejs
RUN apt-get update

# For docker cache
WORKDIR /tmp 
ADD ./Gemfile Gemfile
ADD ./Gemfile.lock Gemfile.lock
ENV BUNDLE_PATH /bundle
RUN gem install bundler --no-rdoc --no-ri
RUN bundle install
# END
ENV APP_HOME /home/web/cluetap_app
RUN mkdir -p $APP_HOME
WORKDIR $APP_HOME
ADD . $APP_HOME
RUN chown -R web:web $APP_HOME
ADD ./nginx/nginx.conf /etc/nginx/
RUN unlink /etc/nginx/sites-enabled/default
ADD ./nginx/cluetap_nginx.conf /etc/nginx/sites-available/
RUN ln -s /etc/nginx/sites-available/cluetap_nginx.conf /etc/nginx/sites-enabled/cluetap_nginx.conf
RUN usermod -a -G sudo web

docker-compose.yml

version: '2'
services:
  postgres:
    image: 'postgres:9.6'
    environment:
      - PGDATA=/var/lib/postgresql/data/pgdata
      - POSTGRES_PASSWORD=
      - POSTGRES_USER=postgres
      - POSTGRES_HOST=cluetapapi_postgres_1
    networks:
      - default
      - service-proxy
    ports:
      - '5432:5432'
    volumes:
      - 'postgres:/var/lib/postgresql/data'
    labels:
      description: "Postgresql Database"
      service: "postgresql"
  web:
    container_name: cluetap_api
    build: .
    command: bash -c "thin start -C config/thin/development.yml && nginx -g 'daemon off;'"
    volumes:
      - .:/home/web/cluetap_app
    ports:
      - "80:80"
    depends_on:
      - 'postgres'
networks:
  service-proxy:
volumes:
  postgres:

When I have run docker-compose build and docker-compose up -d these two commands it run succesfully but when I have hit from the url the it thorught internal server error and the error is 

Unexpected error while processing request: could not connect to server: Connection refused
    Is the server running on host "localhost" (127.0.0.1) and accepting
    TCP/IP connections on port 5432?
could not connect to server: Cannot assign requested address
    Is the server running on host "localhost" (::1) and accepting
    TCP/IP connections on port 5432?

I have applied some solution but it did not work for me, please guide me I am new to docker and AWS.

docker-compose docker ruby-on-rails-5 amazon-ec2 ruby-on-rails
4 Answers

I had this same issue when working on a Rails 6 application in Ubuntu 20.04 using Docker and Traefik.

In my case I was trying to connect the Ruby on Rails application running in a docker container to the PostgreSQL database running on the host.

So each time I try to connect to the database I get the error:

Unexpected error while processing request: could not connect to server: Connection refused
    Is the server running on host "localhost" (127.0.0.1) and accepting
    TCP/IP connections on port 5432?
could not connect to server: Cannot assign requested address
    Is the server running on host "localhost" (::1) and accepting
    TCP/IP connections on port 5432?

Here's how I fixed it:

So first the applications running in the container are exposed to the host via Traefik which maps to the host on port 80.

Firstly, I had to modify my PostgreSQL database configuration file to accept remote connections from other IP addresses. This Stack Overflow answer can help with that - PostgreSQL: FATAL - Peer authentication failed for user (PG::ConnectionBad)

Secondly, I had to create a docker network that Traefik and other applications that will proxy through it will use:

docker network create traefik_default

Thirdly, I setup the applications in the docker-compose.yml file to use the same network that I just created:

version: "3"

services:
  app:
    build:
      context: .
      dockerfile: Dockerfile
    env_file:
      - .env
    environment:
      RAILS_ENV: ${RAILS_ENV}
      RACK_ENV: ${RACK_ENV}
      POSTGRES_USER: ${DATABASE_USER}
      POSTGRES_PASSWORD: ${DATABASE_PASSWORD}
      POSTGRES_DB: ${DATABASE_NAME}
      POSTGRES_HOST_AUTH_METHOD: ${DATABASE_HOST}
      POSTGRES_PORT: ${DATABASE_PORT}
    expose:
      - ${RAILS_PORT}
    networks:
      - traefik_default
    labels:
      - traefik.enable=true
      - traefik.http.routers.my_app.rule=Host(`${RAILS_HOST}`)
      - traefik.http.services.my_app.loadbalancer.server.port=${NGINX_PORT}
      - traefik.docker.network=traefik_default
    restart: always
    volumes:
      - .:/app
      - gem-cache:/usr/local/bundle/gems
      - node-modules:/app/node_modules
  web-server:
    build:
      context: .
      dockerfile: ./nginx/Dockerfile
    depends_on:
    - app
    expose:
      - ${NGINX_PORT}
    restart: always
    volumes:
      - .:/app
networks:
  traefik_default:
    external: true
volumes:
  gem-cache:
  node-modules:

Finally, in my .env file, I specified the private IP address of my host machine as the DATABASE_HOST as an environment variable this way:

DATABASE_NAME=my_app_development
DATABASE_USER=my-username
DATABASE_PASSWORD=passsword1
DATABASE_HOST=192.168.0.156
DATABASE_PORT=5432

RAILS_HOST=my_app.localhost
NGINX_PORT=80

RAILS_ENV=development
RACK_ENV=development
RAILS_MASTER_KEY=e879cbg21ff58a9c50933fe775a74d00
RAILS_PORT=3000
user_109078640

I also had this problem just now. My solution is

  1. Remove port port: '5432:5432' in Postgres service
  2. Change POSTGRES_HOST=cluetapapi_postgres_1 to POSTGRES_HOST=localhost

When you need to access your db, just use like example sqlalchemy.url = postgresql+psycopg2://postgres:password@postgres/dbname

user_98165410
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