# on 0.3.x
cd /var/lib/dokku/plugins
git clone https://github.com/dokku/dokku-postgres.git postgres
dokku plugins-install

# on 0.4.x
dokku plugin:install https://github.com/dokku/dokku-postgres.git postgres

# create a postgres service named lolipop
dokku postgres:create lolipop

# you can also specify the image and image
# version to use for the service
# it *must* be compatible with the
# official postgres image
export POSTGRES_IMAGE="postgres"
export POSTGRES_IMAGE_VERSION="9.4.4"

# you can also specify custom environment
# variables to start the postgres service
# in semi-colon separated forma
export POSTGRES_CUSTOM_ENV="USER=alpha;HOST=beta"

# create a postgres service
dokku postgres:create lolipop

# get connection information as follows
dokku postgres:info lolipop

# a postgres service can be linked to a
# container this will use native docker
# links via the docker-options plugin
# here we link it to our 'playground' app
# NOTE: this will restart your app
dokku postgres:link lolipop playground

# the following environment variables will be set automatically by docker (not
# on the app itself, so they won’t be listed when calling dokku config)
#
#   DOKKU_POSTGRES_LOLIPOP_NAME=/lolipop/DATABASE
#   DOKKU_POSTGRES_LOLIPOP_PORT=tcp://172.17.0.1:5432
#   DOKKU_POSTGRES_LOLIPOP_PORT_5432_TCP=tcp://172.17.0.1:5432
#   DOKKU_POSTGRES_LOLIPOP_PORT_5432_TCP_PROTO=tcp
#   DOKKU_POSTGRES_LOLIPOP_PORT_5432_TCP_PORT=5432
#   DOKKU_POSTGRES_LOLIPOP_PORT_5432_TCP_ADDR=172.17.0.1
#
# and the following will be set on the linked application by default
#
#   DATABASE_URL=postgres://postgres:SOME_PASSWORD@dokku-postgres-lolipop:5432/lolipop
#
# NOTE: the host exposed here only works internally in docker containers. If
# you want your container to be reachable from outside, you should use `expose`.

# another service can be linked to your app
dokku postgres:link other_service playground

# since DATABASE_URL is already in use, another environment variable will be
# generated automatically
#
#   DOKKU_POSTGRES_BLUE_URL=postgres://postgres:ANOTHER_PASSWORD@dokku-postgres-other_service:5432/other_service

# you can then promote the new service to be the primary one
# NOTE: this will restart your app
dokku postgres:promote other_service playground

# this will replace DATABASE_URL with the url from other_service and generate
# another environment variable to hold the previous value if necessary.
# you could end up with the following for example:
#
#   DATABASE_URL=postgres://postgres:ANOTHER_PASSWORD@dokku-postgres-other_service:5432/other_service
#   DOKKU_POSTGRES_BLUE_URL=postgres://postgres:ANOTHER_PASSWORD@dokku-postgres-other_service:5432/other_service
#   DOKKU_POSTGRES_SILVER_URL=postgres://postgres:SOME_PASSWORD@dokku-postgres-lolipop:5432/lolipop

# you can also unlink a postgres service
# NOTE: this will restart your app and unset related environment variables
dokku postgres:unlink lolipop playground

# you can tail logs for a particular service
dokku postgres:logs lolipop
dokku postgres:logs lolipop -t # to tail

# you can dump the database
dokku postgres:export lolipop > lolipop.dump

# you can import a dump
dokku postgres:import lolipop < database.dump

# you can clone an existing database to a new one
dokku postgres:clone lolipop new_database

# finally, you can destroy the container
dokku postgres:destroy lolipop

# Our original DB using default PG 9.4.4
$ dokku postgres:create db9.4

# Migrate it like this for example
$ POSTGRES_IMAGE_VERSION=9.5 dokku postgres:clone db9.4 db9.5

# If it was linked to an application, first link the new DB
$ dokku postgres:link db9.5 my_app
# Then unlink the old one
$ dokku postgres:unlink db9.4 my_app

# And last, destroy the old container
$ dokku postgres:destroy db9.4

$ dokku postgres:connect db < ./dump.sql