pg_dump server and pg_dump version mismatch in docker - postgresql

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 same issue for me, I used an alternative way to take a dump,
First I access the terminal and run the pd_dump inside docker and copied the file from docker to host.
Below are the commands
docker exec -it <container-id> /bin/bash # accessing docker terminal
pg_dump > ~/dump # taking dump inside the docker
docker cp <container-id>:/root/dump ~/dump #copying the dump files to host
Hope the above solution helps.

Answer 2

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.