Docker Postgres Ruby on Rails unable to connect

Question

I am following this tutorial from docker Docker Rails and I have created a folder and added this code below in my docker file.

 FROM ruby:2.5
RUN apt-get update -qq && apt-get install -y build-essential libpq-dev nodejs
RUN mkdir /myapp
WORKDIR /myapp
COPY Gemfile /myapp/Gemfile
COPY Gemfile.lock /myapp/Gemfile.lock
RUN bundle install
COPY . /myapp

And my docker compose file code is:

 version: '3'
services:
  db:
    image: postgres
    volumes:
      - .data:/var/lib/postgresql/data
  web:
    build: .
    command: bundle exec rails s -p 3000 -b '0.0.0.0'
    volumes:
      - .:/myapp
    ports:
      - "3000:3000"
    depends_on:
      - db

I am following tutorial when I am running docker compose up I can just see this error:

Could not connect to server: No such file or directory Is the server running locally and accepting connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?

What is wrong here I don't know how to inspect and detect error how to fix this.

Matt Brictson · Accepted Answer · 2018-06-25 14:34:48Z

7

You need environment variables within your web container so that it knows how to connect to the db container.

version: '3'
services:
  db:
    image: postgres
    environment:
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=
    volumes:
      - ./data:/var/lib/postgresql/data
  web:
    build: .
    command: bundle exec rails s -p 3000 -b '0.0.0.0'
    environment:
      - PGHOST=db
      - PGUSER=postgres
    volumes:
      - .:/myapp
    ports:
      - "3000:3000"
    depends_on:
      - db

edited Jun 25, 2018 at 14:34

answered Jun 24, 2018 at 20:48

Matt Brictson

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1 Comment

user7341673 Over a year ago

when I changed - .data:/var/lib/postgresql/data to - ./data:/var/lib/postgresql/data it solved my problem. Thanks for answering

Dharman · Accepted Answer · 2020-08-24 22:21:13Z

0

Please go to your database.yml and add host set to db , then username and password and run the command again.

edited Aug 24, 2020 at 22:21

Dharman♦

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answered Aug 24, 2020 at 22:15

muwonge nicholus

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