Backup PostgreSQL Database to AWS S3 Storage

backup_database.rb

#!/usr/bin/env ruby
require 'fileutils'

PATH_PG_DUMP = "/usr/lib/postgresql/9.6/bin/pg_dump"
POSTGRES_HOST = "demoscene.t1qwy5zz3sn3.eu-southwest-3.rds.amazonaws.com"
POSTGRES_PORT = 1234
POSTGRES_USERNAME = "admin"
POSTGRES_PASSWORD = "doesnt look like anything to me"
POSTGRES_DBNAME = "main"
AWS_S3_BUCKET = "there.is.no.spoon"

def prepare_filename
    timestamp = Time.now.strftime '%Y%m%d_%H%M%S'
    filename = "demoscene_database_#{timestamp}.sql.gz"
    return filename
end

def create_backup_file(filename)
    puts "will create backup file: '#{filename}'"
    # Invoke `pg_dump` followed by `gzip`
    parts = [
        PATH_PG_DUMP,
        "-Fp",
        "--host \"#{POSTGRES_HOST}\"",
        "--port #{POSTGRES_PORT}",
        "--username #{POSTGRES_USERNAME}",
        "--dbname #{POSTGRES_DBNAME}",
        "| gzip > #{filename}"
    ]
    cmd = parts.join(" ")
    ENV["PGPASSWORD"] = POSTGRES_PASSWORD
    system(cmd)
    bytes = File.size(filename)
    puts "did create backup file: '#{filename}'  bytes: #{bytes}"
end

def upload_to_s3(filename)
    puts "will upload '#{filename}' to S3"
    if File.zero?(filename)
        raise "Expected backup file to be non-empty, but got a 0 byte file!"
    end
    cmd = "aws s3 cp #{filename} s3://#{AWS_S3_BUCKET}"
    system(cmd)
    puts "did upload '#{filename}' to S3"
end

Dir.chdir('/tmp') do
    filename = prepare_filename
    create_backup_file(filename)
    upload_to_s3(filename)
    FileUtils.rm filename, :force => true   # never raises exception
end