Docker Image for PostgreSQL and PgAdmim

You can create your own Docker image by using Dockerfile if there is no Docker image in Docker Hub that suites your need.

Dockerfile For PostgreSQL

The Dockerfile given creates the postgreSQL image by copying the License key and PostgreSQL respository for installing it. And it also creates a User with Password inside which creates an Empty Database which could help us in future steps.

For Building this Dockerfile in command Prompt use the below given command:

$ docker build -t (imageName) .

Example:

$ docker build -t img_postgresql .

Here, Option -t is used to name the image ascontentserverimage, image name should always be in lowercase alphabets and should not contain any spaces . This command could create a Docker image named img_postgresql.

You can check the image created using command $ docker images

To Run this image:

$ docker run -it --name (containerName) (postgresQL_imageName)

Example:

$ docker run -it --name cont_postgresql img_postgresql

This will successfully create the PostgreSQL container named cont_postgresql. The Option '--name' is used to give the proper name to container which should not have any spaces between and the -Flag '-it' is used to run container interactively and attached to your terminal.

Now, using the command $ docker ps you could see the container created/started in the name given (say cont_postgresql).

For Executing the Container:

$ docker exec -it (containerName) bash

Example:

$ docker exec -it cont_postgresql bash

This will create a new Bash session in the container cont_postgresql in terminal.

We can make use of this postgresql database in terminal itself. But for the user intraction we have to make use of postgresql-client. Here we are making use of popular client for PostgreSQL pgAdmin.

Now, you are inside the container and can execute the postgreSQL commands. The following basic postgresql command helps in authenticating and login into the postgres

$ psql -h $PG_PORT_5432_TCP_ADDR -p $PG_PORT_5432_TCP_PORT -d docker -U docker --password

Testing the Database Created

Once you have authenticated and will have a docker =# prompt and you can make use of the postgresql database. As mentioned above, to make sure that a empty database named docker is created you can see in the list of databases and can manipulate in it.

psql (9.3.1)
Type "help" for help.

$ \l
             List of Databases
|        Name      |         owner      |
|docker            |        docker      |
|postgres          |        postgres    |
|template0         |        postgres    |
|template1         |        postgres    |

Create a table in database docker:

$ docker=# CREATE TABLE cities (
no
docker(#     location        varchar(50)
docker(# );
CREATE TABLE
$ docker=# INSERT INTO cities VALUES ('Divya', 'India');
INSERT 0 1
$ docker=# select * from cities;
    name      | location
--------------+------------
   Divya      | India
(1 row)

PgAdmin

You can use the above created Docker Container in the terminal itself. In such case if we need a client interaction, we have to make use of any Postgresql-client. One such popular postgresql-client is pgAdmin. Creating a Container for pgAdmin and port-forwarding the PostgreSQL database to PgAdmin gives the User Interface for postgreSQL database.

Creating the pgAdmin image:

$ docker run --name (PgAdminContainerName) -d -p (hostPort):(ContainerPort) fenglc/pgadmin4

Example:

$ docker run --name pgadmin_cont -d -p 5050:5050 fenglc/pgadmin4

This creates a container of pgAdmin in the name of pgadmin_cont by using the pre-built image fenglc/pgadmin4 in the Docker Hub and can check it in your terminal by using $ docker ps command.

For making use of this postgresql-client container, find the IpAddress of this container in the docker machine and make use of it for port forwarding in the postgresql command as given below:

$  psql -U (userName) -h (postgresql-client_IpAddress) -p (PortOfPgAdmin)

Example:

$ psql -U docker -h 172.17.0.2 -p 5432

NOTE: The Port 5432 is the default port number for postgreSQL using the command

The Docker PostgreSQL_client container IPAddress can be found using the command:

$ docker inspect (postgresql-client_containerName)

Example:

$ docker inspect pgadmin

This will render all the information about the cotainer in a JSON array.

Now, It is successfully built and by opening the browser with the host_IpAddress : port_number will open up the pgAdmin User Interface.

http://localhost:5050

NOTE : We can also make use of Docker Ip address in the place of host_IpAddress in case of connecting a container with another container in same machine.