Rails rake tasks for dump & restore of PostgreSQL databases

db.rake

# lib/tasks/db.rake
namespace :db do

  desc "Dumps the database to db/APP_NAME.dump"
  task :dump => :environment do
    cmd = nil
    with_config do |app, host, db, user|
      cmd = "pg_dump --host #{host} --username #{user} --verbose --clean --no-owner --no-acl --format=c #{db} > #{Rails.root}/db/#{app}.dump"
    end
    puts cmd
    exec cmd
  end

  desc "Restores the database dump at db/APP_NAME.dump."
  task :restore => :environment do
    cmd = nil
    with_config do |app, host, db, user|
      cmd = "pg_restore --verbose --host #{host} --username #{user} --clean --no-owner --no-acl --dbname #{db} #{Rails.root}/db/#{app}.dump"
    end
    Rake::Task["db:drop"].invoke
    Rake::Task["db:create"].invoke
    puts cmd
    exec cmd
  end

  private

  def with_config
    yield Rails.application.class.parent_name.underscore,
      ActiveRecord::Base.connection_config[:host],
      ActiveRecord::Base.connection_config[:database],
      ActiveRecord::Base.connection_config[:username]
  end

end

usage.sh

# dump the development db
rake db:dump

# dump the production db
RAILS_ENV=production rake db:dump

# dump the production db & restore it to the development db
RAILS_ENV=production rake db:dump
rake db:restore

# note: config/database.yml is used for database configuration,
#       but you will be prompted for the database user's password

Thank you @joelvh for editing together a cleaner solution (and I appreciate the pw prompt - makes it a little less likely to accidentally clobber the prod db on restore). Although, in my current test, I'm actually not prompted for a pw when dumping the dev database, but that might have something to do with my local auth-setup for postgresql.

Ed: I've commented out the call to "rake:db:drop/create" - as that requires the user to have create database privileges - and is redundant with pg_restore -c -C (clean/Create). It will work if using something like the "postgres"-user - but rails shouldn't need such high access to the db cluster.

I've made a fork with the code from your comment, for easy download:

cd lib/tasks
curl -O https://gist.githubusercontent.com/e12e/e0c7d2cc1d30d18c8050b309a43450ac/raw/9194cfe92143167a7a15a92ac7f02605bcb9d753/db.rake
# Have a look at the code, before you start clobbering your db... ;-)

The db:dumps task prints the directory listing at the top level db/backups directory, which only lists the environment(s) since the dumps are now placed into subdirectories based on the environment. Can be fixed in one of two ways:

1. Add the -R flag to ls, which recursively lists the contents of the subdirectories:

  task dumps: :environment do
    backup_dir = backup_directory
    puts "#{backup_dir}"
    system "/bin/ls -ltR #{backup_dir}"
  end

2. Specify the environment when calling backup_directory to just get a list of the dumps for the current environment:

  task dumps: :environment do
    backup_dir = backup_directory(Rails.env)
    puts "#{backup_dir}"
    system "/bin/ls -lt #{backup_dir}"
  end

Seems like the best solution depends on your use case - if you're just backing up and restoring in a single environment, then option #2 is probably best.

NOTE Be aware that if PG use OIDs, -o should be inserted in the pg_dump cmd options. *Doc

Thanks to @hopsoft, @joelvh, et al!

This is awesome, thank you all!

Made a fork that combines @joelvh's latest fixes and @e12e's benefits.
Also, added some syntax fixes. Using && instead of and for higher operator precedence.
And removing the else nil from the case statements as those will return nil if none of the cases match by default.

This is my fork:
https://gist.github.com/khalilgharbaoui/96582e28ee47e3bc0839f2a1fe95dd18

@e12e
I have a question regarding restoring the Database. Creating a back up is straight forward and simple. However, when it comes to restoring the database, I keep running into Connection issue. The restore task involves dropping and creating the database. But it fails with:
ActiveRecord::StatementInvalid: PG::ObjectInUse: ERROR: database "database" is being accessed by other users DETAIL: There is 1 other session using the database.

How would I solve this issue? Is there a way to do this without stopping the rails server?

@e12e
I have a question regarding restoring the Database. Creating a back up is straight forward and simple. However, when it comes to restoring the database, I keep running into Connection issue. The restore task involves dropping and creating the database. But it fails with:
ActiveRecord::StatementInvalid: PG::ObjectInUse: ERROR: database "database" is being accessed by other users DETAIL: There is 1 other session using the database.

How would I solve this issue? Is there a way to do this without stopping the rails server?

You must run this query in the pg console before, in order close all connections:

> SELECT pg_terminate_backend(pg_stat_activity.pid)
FROM pg_stat_activity
WHERE pg_stat_activity.datname = 'Your_Data_Base_Name_Here'
  AND pid <> pg_backend_pid();

Awesome team effort guys thanks!

Using version from @khalilgharbaoui

Will this work only for Postgres?

@MwMaki
Yes, pg_dump and pg_restore are specific to Postgres.
You'd probably want to take a look at mysqldump and mysqlimport for MySQL (and maybe for MariaDB).
Not sure about SQL Server and others.

In Rails 6.1 I had to change parent_name for module_parent_name.

# apt install postgresql-client
# apt-get -y install bash-completion wget
# wget --no-check-certificate --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | apt-key add -
# echo "deb http://apt.postgresql.org/pub/repos/apt/ `lsb_release -cs`-pgdg main" | sudo tee /etc/apt/sources.list.d/pgdg.list
# apt-get update
# apt-get -y install postgresql-client-12

namespace :db do

    desc "Dumps the database to backups"
    task :dump => :environment do

        dump_fmt = 'c'      # or 'p', 't', 'd'
        dump_sfx = suffix_for_format dump_fmt
        backup_dir = backup_directory true
        cmd = nil
        with_config do |app, host, db, user|
            file_name = Time.now.strftime("%Y%m%d%H%M%S") + "_" + db + '.' + dump_sfx
            cmd = "PGPASSWORD='postgres' pg_dump -F #{dump_fmt} -v -U postgres -h #{host} -d #{db} -f #{backup_dir}/#{file_name}"
        end
        puts cmd
        exec cmd
    end

    desc "Show the existing database backups"
    task :list => :environment do
        backup_dir = backup_directory
        puts "#{backup_dir}"
        exec "/bin/ls -lt #{backup_dir}"
    end

    desc "Restores the database from a backup using PATTERN"
    task :restore, [:pat] => :environment do |task,args|
        if args.pat.present?
            cmd = nil
            with_config do |app, host, db, user|
                backup_dir = backup_directory
                files = Dir.glob("#{backup_dir}/*#{args.pat}*")
                case files.size
                when 0
                  puts "No backups found for the pattern '#{args.pat}'"
                when 1
                  file = files.first
                  fmt = format_for_file file
                  if fmt.nil?
                    puts "No recognized dump file suffix: #{file}"
                  else
                    cmd = "pg_restore -F #{fmt} -v -c -C #{file}"
                  end
                else
                  puts "Too many files match the pattern '#{args.pat}':"
                  puts ' ' + files.join("\n ")
                  puts "Try a more specific pattern"
                end
            end
            unless cmd.nil?
              Rake::Task["db:drop"].invoke
              Rake::Task["db:create"].invoke
              puts cmd
              exec cmd
            end
        else
            puts 'Please pass a pattern to the task'
        end
    end

    private

    def suffix_for_format suffix
        case suffix
        when 'c' then 'dump'
        when 'p' then 'sql'
        when 't' then 'tar'
        when 'd' then 'dir'
        else nil
        end
    end

    def format_for_file file
        case file
        when /\.dump$/ then 'c'
        when /\.sql$/  then 'p'
        when /\.dir$/  then 'd'
        when /\.tar$/  then 't'
        else nil
        end
    end

    def backup_directory create=false
        backup_dir = "#{Rails.root}/db/backups"
        if create and not Dir.exists?(backup_dir)
          puts "Creating #{backup_dir} .."
          Dir.mkdir(backup_dir)
        end
        backup_dir
    end

    def with_config
        yield Rails.application.class.module_parent_name.underscore,
              ActiveRecord::Base.connection_config[:host],
              ActiveRecord::Base.connection_config[:database]
    end

end

You guys are the real MVP

This is broken for rails 7.x because ActiveRecord::Base.connection_config interface is now changed. Here is a link to my gist which handles newer rails interface:

https://gist.github.com/amit/45e750edde94b70431f5d42caadee423