Docker compose fiware WireCloud data persistance not loaded from volume - postgresql

Question

I am using a docker container for my FiWare WireCloud. It is working properly but when I stop my container with docker compose down and restart it with docker compose up all my data are erased even if I specified a volume for the postgresql database and I have the following error:
ERROR: relation "wirecloud_workspace" does not exist at character 370
If I want to make it work again, I have to recreate the whole database from scratch (initdb & createsuperuser)
What I would like to do is to be able to save my wirecloud data inside a volume and be able te backup it and reload it. Here is my current docker-compose.yml file in version 3:
version: '3.3'
services:
iot-mongo:
image: mongo:3.2
ports:
- "27017:27017"
volumes:
- ./data/mongo:/data/db
orion:
image: fiware/orion:1.9.0
links:
- iot-mongo
ports:
- "1026:1026"
command: -dbhost iot-mongo
nginx:
restart: always
image: nginx:1.13
ports:
- "80:80"
- "443:443"
volumes:
- ./nginx/nginx.conf:/etc/nginx/nginx.conf:ro
- ./nginx/sites-available:/etc/nginx/sites-available
- ./letsencrypt/well-known:/www/letsencrypt
- /etc/letsencrypt/:/etc/letsencrypt/
- wirecloudwww:/var/www/static
- wirecloudinstance:/opt/wirecloud_instance
links:
- wirecloud:wirecloud
- orion:orion
postgres:
restart: always
image: postgres:latest
ports:
- "5432:5432"
volumes:
- postgresdata:/var/lib/postgresql
environment:
POSTGRES_USER: postgres
POSTGRES_PASSWORD:
POSTGRES_DB: postgres
PGDATA: /tmp
wirecloud:
restart: always
image: fiware/wirecloud:1.0-composable
links:
- postgres:postgres
volumes:
- wirecloudwww:/var/www/static
- wirecloudinstance:/opt/wirecloud_instance
volumes:
wirecloudwww: {}
wirecloudinstance: {}
postgresdata: {}
I also tried with docker-compose v1 like they show in the documentation but the result is the same.

Answer 1

The problem is the definition of the postgres volume and the PGDATA environment variable. The PGDATA environment is telling PostgreSQL to store data in /tmp, so it is not going to store data inside de volume (you can create a volume on /tmp, but this seems a bit strange). If you remove the PGDATA environment variable, postgres will store data into /var/lib/postgresql/data. Using this definition for the postgres service should do the trick:
postgres:
restart: always
image: postgres:latest
ports:
- "5432:5432"
volumes:
- postgresdata:/var/lib/postgresql/data
environment:
POSTGRES_USER: postgres
POSTGRES_PASSWORD:
POSTGRES_DB: postgres