The files needed for getting a rails app running with postgres and pulling in the data from your old mysql database. As per my video here: https://youtu.be/2SOfvPZJZoM

.env

PORT=3000

# postgresql
POSTGRES_HOST=localhost
POSTGRES_PORT=54323
POSTGRES_DBUSER=postgres
POSTGRES_PASSWORD=philsmy123

# mysql
MYSQL_DBNAME=lotteryportal_development
MYSQL_DBUSER=mysqluser
MYSQL_DBPASS=philsmy123
MYSQL_DBPORT=13306
TZ=Asia/Tokyo

database.yml

# PostgreSQL. Versions 9.3 and up are supported.
#
# Install the pg driver:
#   gem install pg
# On macOS with Homebrew:
#   gem install pg -- --with-pg-config=/usr/local/bin/pg_config
# On macOS with MacPorts:
#   gem install pg -- --with-pg-config=/opt/local/lib/postgresql84/bin/pg_config
# On Windows:
#   gem install pg
#       Choose the win32 build.
#       Install PostgreSQL and put its /bin directory on your path.
#
# Configure Using Gemfile
# gem "pg"
#
default: &default
  adapter: postgresql
  encoding: unicode
  # For details on connection pooling, see Rails configuration guide
  # https://guides.rubyonrails.org/configuring.html#database-pooling
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>

development:
  <<: *default
  host: <%= ENV['POSTGRES_HOST'] %>
  port: <%= ENV['POSTGRES_PORT'] %>
  username: <%= ENV['POSTGRES_USER'] %>
  password: <%= ENV['POSTGRES_PASSWORD'] %>
  database: lotteryportal_development

test:
  <<: *default
  host: <%= ENV['POSTGRES_HOST'] %>
  port: <%= ENV['POSTGRES_PORT'] %>
  username: <%= ENV['POSTGRES_USER'] %>
  password: <%= ENV['POSTGRES_PASSWORD'] %>
  database: lotteryportal_test

production:
  <<: *default
  url: <%= ENV['DATABASE_URL'] %>

docker-compose.yml

version: "3.7"
services:
  db:
    image: postgres:13.5
    container_name: "lottery_postgres"
    command: ["postgres", "-c", "logging_collector=on", "-c", "log_filename=postgresql.log", "-c", "log_statement=all"]
    environment:
      POSTGRES_PASSWORD: "${POSTGRES_PASSWORD}"
    ports:
      - 54323:5432
    volumes:
      - lottery_dbdata:/var/lib/postgresql/data
# this is only here for the migration. Not needed for the actual service
  mysqldb:
    image: mysql:8.0
    volumes:
      - mysqldb-store:/var/lib/mysql
      - ./logs:/var/log/mysql
      - ./docker/mysql/my.cnf:/etc/mysql/conf.d/my.cnf
    environment:
      - MYSQL_DATABASE=${MYSQL_DBNAME}
      - MYSQL_USER=${MYSQL_DBUSER}
      - MYSQL_PASSWORD=${MYSQL_DBPASS}
      - MYSQL_ROOT_PASSWORD=${MYSQL_DBPASS}
      - TZ=${TZ}
    ports:
      - ${MYSQL_DBPORT}:3306
volumes:
  lottery_dbdata:
  mysqldb-store:

pgloader-commands

-- See https://github.com/dimitri/pgloader/blob/master/pgloader.1.md for
-- connection string options.

LOAD DATABASE
    FROM mysql://root:philsmy123@127.0.0.1:13306/lotteryportal_development
    INTO postgresql://postgres:philsmy123@127.0.0.1:54323/lotteryportal_development

ALTER SCHEMA 'lotteryportal_development' RENAME TO 'public'
WITH data only, truncate, prefetch rows = 10000;

run-pgloader.sh

#!/bin/bash

docker pull dimitri/pgloader
docker run --rm --name pgloader dimitri/pgloader:latest pgloader --version
docker run --rm --name pgloader dimitri/pgloader:latest pgloader --help
docker run --rm  --network host --name pgloader -v <your Rails root or wherever you have you command file>:/data dimitri/pgloader:latest pgloader --verbose /data/pgloader-commands