To configure your database, you will need to edit the config/database.yml file.


The defaults are set to use MySQL, but Wagn has been well tested in PostgreSQL (including full-text search), and there are rumors that it functions properly with SQLite too.


This is a standard Ruby-on-Rails setup, so if you encounter problems with database configuration and can't find answers here, considering broadening your search beyond "wagn database installation" to "rails database installation".


Engine-Specific help:

install posgresql 9.4

mkdir install_pg
cd install_pg
sudo yum -y install
sudo yum -y groupinstall "PostgreSQL Database Server 9.4 PGDG"

check if everything was correctly installed

sudo rpm -qa | grep postgre

enable & start service

sudo systemctl enable postgresql-9.4
sudo systemctl start postgresql-9.4.service

initialize database

sudo /usr/pgsql-9.4/bin/postgresql94-setup initdb

firewall adjustment (open ports)

firewall-cmd --permanent --add-port=5432/tcp
firewall-cmd --permanent --add-port=80/tcp
firewall-cmd --reload

enable SELinux

setsebool -P httpd_can_network_connect_db 1

change password for the

sudo passwd postgres (user prompted twice for a password)

edit the posgresql configuration file

vim /var/lib/pgsql/9.4/data/pg_hba.conf
Change from:
host    all             all               ident
# IPv6 local connections:
host    all             all             ::1/128                 ident
host    all             all               md5
# IPv6 local connections:
host    all             all             ::1/128                 md5

posgresql 9.4 binaries (should set postgresql ENV!)

all postgresql 9.4 binaries are installed at /usr/pgsql-9.4/bin

Change password for the 'postgres' user

sudo passwd postgres

If root/sudo rights are unavailable use sudo:
sudo -i -u postgres
at the prompt then enter:
passwd to change the user password

Decko installation

create a db user (asks for the password twice) will have to be written at the config/database.yml

# -d (--createdb) (role can create new databases)
# -P (--pwprompt) (assign a password to new role)
createuser -d <db_user> -P (CREATE ROLE alias)

create database which will have to be written at the config/database.yml

# probably not needed decko seed will create the database
# create database via user
# -O (--owner=OWner) (database user to own the new database)
# createdb -O <db_user> <database>

Edit Gemfile and add the pg gem

gem 'pg', '~> 0.18'

edit config/database.yml

# Add this after the cucumber: *test line

production: &production
  adapter: postgresql
  encoding: utf8
  reconnect: false
  database: <database_name>
  pool: 5
  username: <db_user>
  password: <db_user_password>
  host: localhost

I'm fuzzy here on the profile (probably if you want to change to production then change it?)
@ethn could you please fill it here?
profile: *production

What is the correct format for production deployment?

Now to install all gems and seed the application

install decko gem

gem install decko

install new application

decko new _app_name_

change directory

cd _app_name_

install all needed gems (this is probably optional but I'm used to doing it manually)

bundle install

prefill the DB and have the original configuration

decko seed

If everything went fine you should see:

bundle exec rake decko:seed
--> Database '<db_name>' already exists  (This is extra as I had the database already)
not dropped
loading schema
-- create_table("card_actions", {:id=>:integer, :force=>:cascade})
   -> 0.0542s
-- create_table("card_acts", {:id=>:integer, :force=>:cascade})
   -> 0.0250s
-- create_table("card_changes", {:id=>:integer, :force=>:cascade})
   -> 0.0121s
-- create_table("card_references", {:id=>:integer, :force=>:cascade})
   -> 0.0290s
-- create_table("card_revisions", {:id=>:integer, :force=>:cascade})
   -> 0.0157s
-- create_table("cards", {:id=>:integer, :force=>:cascade})
   -> 0.0571s
-- create_table("delayed_jobs", {:force=>:cascade})
   -> 0.0146s
-- create_table("schema_migrations_core_cards", {:id=>false, :force=>:cascade})
   -> 0.0095s
-- create_table("schema_migrations_deck_cards", {:id=>false, :force=>:cascade})
   -> 0.0084s
-- create_table("sessions", {:id=>:integer, :force=>:cascade})
   -> 0.0107s
-- create_table("users", {:id=>:integer, :force=>:cascade})
   -> 0.0073s
update card_migrations
-- assume_migrated_upto_version("20170830210517", ["/home/smalltalk/.rvm/gems/ruby-2.3.0/gems/card-1.93.8/db/migrate_core_cards"])
   -> 0.0321s
loading bootstrap
set symlink for assets
reset cache

Then you can start the built-in WEBrick server as mentioned at the

You should see (when started correctly):

decko server
=> Booting Thin
=> Rails 5.1.4 application starting in production on
=> Run `rails server -h` for more startup options
Thin web server (v1.7.2 codename Bachmanity)
Maximum connections set to 1024
Listening on, CTRL+C to stop


Install the package:

# apt-get install mysql2


Try to install the gem

$ gem install mysql2


If you're planning on using the mysql2 gem for your application then you'll want to install the libmysqlclient-dev package before you do that. Without it, you'll get an error when the gem tries to compile its native extensions:


Building native extensions.  This could take a while...

ERROR:  Error installing mysql2:

    ERROR: Failed to build gem native extension.


    /home/ryan/.rubies/ruby-2.2.0/bin/ruby extconf.rb

checking for ruby/thread.h... yes

checking for rb_thread_call_without_gvl() in ruby/thread.h... yes

checking for rb_thread_blocking_region()... yes

checking for rb_wait_for_single_fd()... yes

checking for rb_hash_dup()... yes

checking for rb_intern3()... yes

checking for mysql_query() in -lmysqlclient... no

checking for main() in -lm... yes

checking for mysql_query() in -lmysqlclient... no

checking for main() in -lz... yes

checking for mysql_query() in -lmysqlclient... no

checking for main() in -lsocket... no

checking for mysql_query() in -lmysqlclient... no

checking for main() in -lnsl... yes

checking for mysql_query() in -lmysqlclient... no

checking for main() in -lmygcc... no

checking for mysql_query() in -lmysqlclient... no

*** extconf.rb failed ***

Could not create Makefile due to some reason, probably lack of necessary

libraries and/or headers.  Check the mkmf.log file for more details.  You may

need configuration options.


Install this package using:

$ sudo apt-get install libmysqlclient-dev


If you are running mysql and rake complains about not being able to find your mysql.sock file, you will need to add "socket: " to each of the database definitions

Example database.yml for Development

adapter: mysql
socket: /var/mysql/mysql.sock
database: wagn_development
username: wagn
password: hi_im_a_password_right_up_in_here
host: localhost


adapter: mysql
socket: /var/mysql/mysql.sock
database: wagn_test
username: wagn
password: woo_hoo_password
host: localhost

adapter: mysql
socket: /var/mysql/mysql.sock
database: wagn_production
username: wagn
password: password_ahoy
host: localhost