Run a docker PostgreSQL instance locally for Testing

Running a PostgreSQL instance ad-hoc for testing is not always as bootstraping as it should be. This blog will run a PostgreSQL instance that connects to your workstation’s network and instead of using one of the popular tools like dbeaver we shall use the client that comes with the instance. Also we shall run a bootstrap script to have some data pre-inserted.

Let’s get started by running the instance. On purpose I will use another port. On scenarios of multiple instances running in your workstation, port collisions are likely. The workaround would be to choose port 5433.

docker run --rm --name test-instance -e POSTGRES_PASSWORD=password -p 5433:5432 postgres

This will run PostgreSQL and you shall be able to connect to port 5433. On a CTRL-C the instance will be stopped and destroyed.

Now instead of using an external tool to connect let’s use the instance itself, it comes with psql pre-installed.

docker exec -it test-instance /bin/bash
> psql postgres postgres
postgres=# \h
Available help:
  ABORT                            ALTER TRIGGER                    CREATE RULE                      DROP GROUP                       LISTEN
  ALTER AGGREGATE                  ALTER TYPE                       CREATE SCHEMA                    DROP INDEX                       LOAD
  ALTER COLLATION                  ALTER USER                       CREATE SEQUENCE                  DROP LANGUAGE                    LOCK
.....
postgres=# \q

The instance works and connections from the outside are possible.

Next step would be to bootstrap a db initialization script.

#!/bin/bash
set -e
 
psql -v ON_ERROR_STOP=1 --username postgres --dbname postgres <<-EOSQL
    create schema test_schema;
 
    create table test_schema.employee(
        id  SERIAL PRIMARY KEY,
        firstname   TEXT    NOT NULL,
        lastname    TEXT    NOT NULL,
        email       TEXT    not null,
        age         INT     NOT NULL,
        salary         real,
        unique(email)
    );
 
    insert into test_schema.employee (firstname,lastname,email,age,salary)
    values ('John','Doe 1','john1@doe.com',18,1234.23);

EOSQL

Supposing the file with the script is called init_db.sh

Let’s run the command with the initialization schema mounted.

docker run --rm --name test-instance -v /path/to/init_db.sh:/docker-entrypoint-initdb.d/init-db-script.sh -e POSTGRES_PASSWORD=password -p 5433:5432 postgres

And let’s check the results.

docker exec -it test-instance /bin/bash
>psql postgres postgres
postgres=# SELECT*FROM test_schema.employee;
 id | firstname | lastname |     email     | age | salary
----+-----------+----------+---------------+-----+---------
  1 | John      | Doe 1    | john1@doe.com |  18 | 1234.23
(1 row)

That’s it! You created a Postgresql database through docker, you did connect to it also you added a bootstrap script with data.