pg_dump server and pg_dump version mismatch in docker

Question

When I run the command psql --version within the railsApp container, I get 9.4.12 and when I run the same within the postgres container, I get 9.6.2. How can I get the versions to match?

I am getting the following error when I try to do a migration on Rails App which does a pg_dump sql import.

pg_dump: server version: 9.6.2; pg_dump version: 9.4.12
pg_dump: aborting because of server version mismatch
rails aborted!

Here's my Docker-compose.yml file:

version: "2.1"
services:
  railsApp:
    build:
      context: ./
    ports:
      - "3000:3000"
    links:
      - postgres
    volumes:
      - .:/app
  postgres:
    image: postgres:9.6
    ports:
      - "5432:5432"
    volumes:
      - ./.postgres:/var/lib/postgresql

The Dockerfile:

FROM ruby:2.3.3

# setup /app as our working directory
RUN mkdir /app
WORKDIR /app

# Replace shell with bash so we can source files
RUN rm /bin/sh && ln -s /bin/bash /bin/sh

# Set debconf to run non-interactively
RUN echo 'debconf debconf/frontend select Noninteractive' | debconf-set-selections

# Install base dependencies

FROM ruby:2.3.3

# setup /app as our working directory
RUN mkdir /app
WORKDIR /app

# Replace shell with bash so we can source files
RUN rm /bin/sh && ln -s /bin/bash /bin/sh

# Set debconf to run non-interactively
RUN echo 'debconf debconf/frontend select Noninteractive' | debconf-set-selections

# Install base dependencies
RUN apt-get update && apt-get install -y -q --no-install-recommends \
        apt-transport-https \
        build-essential \
        ca-certificates \
        curl \
        git \
        libssl-dev \
        python \
        rsync \
        software-properties-common \
        wget \
        postgresql-client \
        graphicsmagick \
    && rm -rf /var/lib/apt/lists/*

# Install node and npm with nvm
RUN curl https://raw.githubusercontent.com/creationix/nvm/v0.33.0/install.sh | bash

ENV NVM_DIR=/root/.nvm
ENV NODE_VERSION v7.2.1

ENV NODE_PATH $NVM_DIR/versions/node/$NODE_VERSION
ENV PATH      $NODE_PATH/bin:./node_modules/.bin:$PATH


RUN source $NVM_DIR/nvm.sh \
    && nvm install $NODE_VERSION \
    && nvm alias default $NODE_VERSION \
    && nvm use default

# Install our ruby dependencies
ADD Gemfile Gemfile.lock /app/
RUN bundle install

# copy the rest of our code over
ADD . /app

ENV RAILS_ENV development
ENV SECRET_KEY_BASE a6bdc5f788624f00b68ff82456d94bf81bb50c2e114b2be19af2e6a9b76f9307b11d05af4093395b0471c4141b3cd638356f888e90080f8ae60710f992beba8f

# Expose port 3000 to the Docker host, so we can access it from the outside.
EXPOSE 3000

# Set the default command to run our server on port 3000
CMD ["rails", "server", "-p", "3000", "-b", "0.0.0.0"]

Answer 1

The easiest approach is to use the correct postgres version in the docker-compose. Change:

  postgres:
    image: postgres:9.6

To:

  postgres:
    image: postgres:9.4.2

All available versions here.