We are defining the postgres (user ) password to "postgres" and creating a database called "test" on the exemple below
docker run -d -ePOSTGRES_USER=postgres -ePOSTGRES_PASSWORD=postgres -ePOSTGRES_DB=test -p5432:5432 --name postgres postgres:10.4-alpine
Testing
docker exec -it postgres bash
su - postgres
c585f5ed70df:~$ psql
psql (10.4)
Type "help" for help.
postgres=# \c test
You are now connected to database "test" as user "postgres".
test=#
test=# INSERT INTO distributors VALUES (101,'DESCRIPTION OF DID 1');
INSERT 0 1
test=# select * from distributors;
did | name
-----+----------------------
101 | DESCRIPTION OF DID 1