Dockerfile ruby standalone_migrations postgresql example

Dockerfile

FROM ruby:2.6.5-alpine3.10

# Install dependencies
RUN apk update && apk add build-base bash postgresql-dev zlib-dev

# Install gems
RUN gem install rake dotenv pg standalone_migrations

# Set postgres environment variables
ENV POSTGRES_HOST=127.0.0.1
ENV POSTGRES_PORT=54320
ENV POSTGRES_USER=docker
ENV POSTGRES_PASS=docker
ENV POSTGRES_DBNAME=docker

# Copy local repo into docker
COPY migration/ /migration

# Set working directory to be migration directory
WORKDIR /migration

# Set the default command to run when starting the container
CMD ["rake", "db:migrate"]