This repository creates a Docker image with a postgres server that can be used by QWC.
The image contains the postgres server, the postgis extension,
and scripts to set up the qwc_configdb configuration database
and scripts to insert the demo data.
When the image is run, then it checks whether the directory
referenced by the $PGDATA ENV variable is empty. If that's
the case then it will proceed with setting up the
qwc_configdb DB and adding demo data to the qwc_demo DB.
The https://github.com/qwc-services/qwc-demo-db repository uses this image to create another container image with a ready to use database filled with demo data for easy trying out QWC2.
The qwc-base-db Docker image is based on the official Postgres Docker container image. The mechanisms discussed below are based on those provided by the Postgres Docker image. Please see at the mentioned link.
The qwc-base-db Docker container image meant to be used like this:
$ cat docker-compose.yml
version: '2.1'
services:
qwc-postgis:
image: sourcepole/qwc-base-db
environment:
- ALEMBIC_VERSION=head
- PGDATA=/var/lib/postgresql/data/pgdata
healthcheck:
test: ["CMD-SHELL", "pg_isready -U postgres"]
interval: 10s
ports:
- "0.0.0.0:5432:5432"
volumes:
- ./volumes/postgres-data:/var/lib/postgresql/data
[...]
Upon start, the container will check whether /var/lib/postgresql/data
is empty.
If /var/lib/postgresql/data is empty, then postgres will initialize it
and execute scripts under /docker-entrypoint-initdb.d that will set up
a qwc_demo DB and fill it with demo data.
If /var/lib/postgresql/data is NOT empty, such as when:
-
the container had already been started in the past and had already initialized the the DB inside the provided volume or
-
the admin has attached a volume to the container that had some other postgres database in it
then postgres will just start and try to use the data that is already
under /var/lib/postgresql/data.