This project will be an introduction to using the Docker platform with a PostgreSQL database. After creating a new Spring Boot project, I checked that it ran correctly with the commands
./gradlew test
./gradlew bootRun # launced on http://localhost:8080 in browser
./gradlew bootJar # application jar in build/directory
I checked that I already had Docker and PostgresSQL installed in my computer.
$ docker -v
Docker version 27.1.1, build 6312585
$ docker pull postgres
Using default tag: latest
latest: Pulling from library/postgres
Digest: sha256:4ec37d2a07a0067f176fdcc9d4bb633a5724d2cc4f892c7a2046d054bb6939e5
Status: Image is up to date for postgres:latest
docker.io/library/postgres:latest
Initially, I had no running Docker containers:
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
By default, PostgreSQL uses port 5432, so I mapped the port on both host and container with the argument -p 5432:5432,
and set the username and password with the environmental argument -e.
amali@MampendaPC MINGW64 ~/IdeaProjects/DAT250/docker-intro/docker-intro (main)
$ docker run -p 5432:5432 -e POSTGRES_USER=myusername -e POSTGRES_PASSWORD=mypassword -e POSTGRES_DB=mydatabase -d --name my-postgres --rm postgres postgres
dfbd112eca53a482da5d4b289cfa977dcc3a85e04a61142ba47381ce420d2857
After which, I could see my running Docker container:
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
23fe9671801e postgres "docker-entrypoint.s…" 17 seconds ago Up 16 seconds 0.0.0.0:5432->5432/tcp my-postgres
Once this was done, I opened Settings > Build, Execution, Deployment > Docker and clicked on the "Add"-button
(plus) sign in the upper left corner. IntelliJ detected that I was running Docker Desktop and sat all the fields for me,
so I could see the message "Connection successful" in the lower left corner. I clicked "Apply" and "OK" and opened
Services where I could see the Docker daemon running and clicked "connect" (green play button).
I was unable to connect to the running Docker container, so I stopped and deleted it. Then, opened Services > Docker >
Images in IntelliJ again and right-clicked Images, where a drop-down menu appeared with the option to
"Create container". A new window opened, prompting for me to input some values into the fields. So I filled it in
accordingly:
This did not work either because I kept getting errors when trying to enter the container bash.
psql: FATAL: role "postgres" does not exist
psql: FATAL: role "my-username" does not exist
psql: FATAL: role "user" does not exist
So, I deleted the container and tried again:
amali@MampendaPC MINGW64 ~
$ docker run -p 5432:5432 -e POSTGRES_PASSWORD=mypassword -e POSTGRES_USERNAME=myusername -d --name my-postgres --rm postgres postgres
32e0e9dcd8d4fbafe9b4493bc64df5f6afc6c77d820b71e0d3e61eb1081d175e
amali@MampendaPC MINGW64 ~
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
32e0e9dcd8d4 postgres "docker-entrypoint.s…" 21 seconds ago Up 21 seconds 0.0.0.0:5432->5432/tcp my-postgres
amali@MampendaPC MINGW64 ~
$ winpty docker exec -it my-postgres bash
root@73261b55aedb:/# psql -U postgres
psql (17.0 (Debian 17.0-1.pgdg120+1))
Type "help" for help.
postgres=# create user myusername with password 'mypassword';
CREATE ROLE
postgres=# \du
List of roles
Role name | Attributes
------------+------------------------------------------------------------
myusername |
postgres | Superuser, Create role, Create DB, Replication, Bypass RLS
postgres=# create database test;
CREATE DATABASE
postgres=# \l
List of databases
Name | Owner | Encoding | Locale Provider | Collate | Ctype | Locale | ICU Rules | Access privileges
-----------+----------+----------+-----------------+------------+------------+--------+-----------+-----------------------
postgres | postgres | UTF8 | libc | en_US.utf8 | en_US.utf8 | | |
template0 | postgres | UTF8 | libc | en_US.utf8 | en_US.utf8 | | | =c/postgres +
| | | | | | | | postgres=CTc/postgres
template1 | postgres | UTF8 | libc | en_US.utf8 | en_US.utf8 | | | =c/postgres +
| | | | | | | | postgres=CTc/postgres
test | postgres | UTF8 | libc | en_US.utf8 | en_US.utf8 | | |
(4 rows)
postgres=# \c test
You are now connected to database "test" as user "postgres".
test=# \d
Did not find any relations.
I opened another gitBash terminal and ran the command (password: 1234)
amali@MampendaPC MINGW64 ~
$ psql -h localhost -p 5432 -U postgres
Password for user postgres:
psql (17.0)
Type "help" for help.
postgres=# create database test2;
CREATE DATABASE
postgres=# \c test
You are now connected to database "test" as user "postgres".