Postgres Database Configuration.md

Steps necessary to configure a Postgres Database

1. Download image from registry

We can download the image from docker registry with the command: docker pull postgres:latest

2. Create the container with the image

We must create a container with the image downloaded from the registry, to perform this operation we must execute docker container run command providing the flags to configure the container properly, as we can see below:

docker container run -d --volume /opt/volume/postgressql:/var/lib/postgressql/data -p 5432:5432 -e POSTGRES_PASSWORD=<password> -e POSTGRES_USER=<user> --name postgres postgres:latest

The flags used here were:

• -d: to detatch the container from the current shell session
• --volume: to provide a volume to the container, in this case will be the directory /opt/volume/postgressql
• -p: to map the ports to the conainer
• -e: to stablish environment variables, in this case we are estabilishing an user and also a passsword
• --name: to provide a name for the container

3. Configure security policies

To configure the security policies we must enter in the container create a new database to our application and configure the ecurity policies to this application.

1. Enter the container with the default credentials: docker exec -ti <container_name> psql -U <user>
2. Create a database specially for our application and then create a user also for the application:

CREATE DATABASE <appname>;
CREATE USER <appuser> WITH ENCRYPTED PASSWORD '<password>;'
GRANT ALL PRIVILEGES ON DATABASE <appname> TO <appuser>;

3. Log out from the current session on container and re-enter as the new user created in the step above: docker container exec -ti <container_name> psql -U <appuser> -d <appname>
4. Grant CRUD and table management privileges to your user:

GRANT SELECT, INSERT, UPDATE, DELETE ON ALL TABLES IN SCHEMA public TO <appuser>;
GRANT CREATE, USAGE ON SCHEMA public TO <appuser>;
GRANT TRUNCATE, REFERENCES ON ALL TABLES IN SCHEMA public TO <appuser>;

5. Log out again an re-enter in the container with the default creadentials: docker container exec -ti <container_name> psql -U <user>
6. Change the database owner to the application:

ALTER DATABASE <appname> OWNER TO <appuser>; 

Now we have an valid database for any application that we want to run.