Red Hat OpenShift Development I: Introduction to Containers with Podman

Instructions

1. Create a compose file that contains the definition of a PostgreSQL server.

   1. Change to the ~/DO188/labs/compose-environments directory and open the compose.yml file.

      [student@workstation ~]$ cd ~/DO188/labs/compose-environments
      [student@workstation compose-environments]$ gedit compose.yml

   2. Define a database container that uses the registry.ocp4.example.com:8443/rhel9/postgresql-13:1 image. Forward port 5432 from the localhost to the same port inside the container.

      services:
        db:
          image: "registry.ocp4.example.com:8443/rhel9/postgresql-13:1"
          ports:
            - "5432:5432"

   3. Define the following environment variables:

      Field	Value
      POSTGRESQL_USER	backend
      POSTGRESQL_DATABASE	rpi-store
      POSTGRESQL_PASSWORD	redhat

      services:
        db:
          image: "registry.ocp4.example.com:8443/rhel9/postgresql-13:1"
          environment:
            POSTGRESQL_USER: backend
            POSTGRESQL_DATABASE: rpi-store
            POSTGRESQL_PASSWORD: redhat
          ports:
            - "5432:5432"

   4. Bind mount the ~/DO188/labs/compose-environments/database_scripts directory to the /opt/app-root/src/postgresql-start directory with the Z option for SELinux. You can use the relative path to the compose.yml file for the database_scripts directory as the bind mount.

      services:
        db:
          image: "registry.ocp4.example.com:8443/rhel9/postgresql-13:1"
          environment:
            POSTGRESQL_USER: backend
            POSTGRESQL_DATABASE: rpi-store
            POSTGRESQL_PASSWORD: redhat
          ports:
            - "5432:5432"
          volumes:
            - ./database_scripts:/opt/app-root/src/postgresql-start:Z

   5. Define a persistent volume called rpi for the container. Bind mount the rpi volume to the /var/lib/pgsql/data directory in the container.

      services:
        db:
          image: "registry.ocp4.example.com:8443/rhel9/postgresql-13:1"
          environment:
            POSTGRESQL_USER: backend
            POSTGRESQL_DATABASE: rpi-store
            POSTGRESQL_PASSWORD: redhat
          ports:
            - "5432:5432"
          volumes:
            - ./database_scripts:/opt/app-root/src/postgresql-start:Z
            - rpi:/var/lib/pgsql/data
      
      volumes:
        rpi: {}

   6. Call the container compose_environments_postgresql, and save the file.

      services:
        db:
          image: "registry.ocp4.example.com:8443/rhel9/postgresql-13:1"
          container_name: "compose_environments_postgresql"
          environment:
            POSTGRESQL_USER: backend
            POSTGRESQL_DATABASE: rpi-store
            POSTGRESQL_PASSWORD: redhat
          ports:
            - "5432:5432"
          volumes:
            - ./database_scripts:/opt/app-root/src/postgresql-start:Z
            - rpi:/var/lib/pgsql/data
      volumes:
        rpi: {}

2. Define a pgAdmin server in the compose.yml file.

   1. Define a database admin interface container that uses the registry.ocp4.example.com:8443/crunchydata/crunchy-pgadmin4:ubi8-4.30-1 image. Map port 5050 from the container to port 5050 on the host.

      services:
        db-admin:
          image: "registry.ocp4.example.com:8443/crunchydata/crunchy-pgadmin4:ubi8-4.30-1"
          ports:
            - "5050:5050"
        db:
          image: "registry.ocp4.example.com:8443/rhel9/postgresql-13:1"
          container_name: "compose_environments_postgresql"
          environment:
            POSTGRESQL_USER: backend
            POSTGRESQL_DATABASE: rpi-store
            POSTGRESQL_PASSWORD: redhat
          ports:
            - "5432:5432"
          volumes:
            - ./database_scripts:/opt/app-root/src/postgresql-start:Z
            - rpi:/var/lib/pgsql/data
      
      volumes:
        rpi: {}

   2. Define the following environment variables:

      Field	Value
      PGADMIN_SETUP_EMAIL	user@example.com
      PGADMIN_SETUP_PASSWORD	redhat

      services:
        db-admin:
          image: "registry.ocp4.example.com:8443/crunchydata/crunchy-pgadmin4:ubi8-4.30-1"
          environment:
            PGADMIN_SETUP_EMAIL: user@example.com
            PGADMIN_SETUP_PASSWORD: redhat
          ports:
            - "5050:5050"
        db:
          image: "registry.ocp4.example.com:8443/rhel9/postgresql-13:1"
          container_name: "compose_environments_postgresql"
          environment:
            POSTGRESQL_USER: backend
            POSTGRESQL_DATABASE: rpi-store
            POSTGRESQL_PASSWORD: redhat
          ports:
            - "5432:5432"
          volumes:
            - ./database_scripts:/opt/app-root/src/postgresql-start:Z
            - rpi:/var/lib/pgsql/data
      
      volumes:
        rpi: {}

   3. Name the container compose_environments_pgadmin. Save and close the file.

      services:
        db-admin:
          image: "registry.ocp4.example.com:8443/crunchydata/crunchy-pgadmin4:ubi8-4.30-1"
          container_name: "compose_environments_pgadmin"
          environment:
            PGADMIN_SETUP_EMAIL: user@example.com
            PGADMIN_SETUP_PASSWORD: redhat
          ports:
            - "5050:5050"
        db:
          image: "registry.ocp4.example.com:8443/rhel9/postgresql-13:1"
          container_name: "compose_environments_postgresql"
          environment:
            POSTGRESQL_USER: backend
            POSTGRESQL_DATABASE: rpi-store
            POSTGRESQL_PASSWORD: redhat
          ports:
            - "5432:5432"
          volumes:
            - ./database_scripts:/opt/app-root/src/postgresql-start:Z
            - rpi:/var/lib/pgsql/data
      
      volumes:
        rpi: {}

      Note

      You can refer to the completed compose.yml file in the ~/DO188/solutions/compose-environments directory.

3. Run the developer environment.

   1. From the ~/DO188/labs/compose-environments directory, use the compose.yml file to start the containerized development environment. Use the -d option to run the containers in the background.

      [student@workstation compose-environments]$ podman-compose up -d
      ['podman', '--version', '']
      using podman version: ...
      ** excluding:  set()
      ['podman', 'network', 'exists', 'compose-environments_default']
      ...output omitted...
      exit code: 0

   2. Confirm that the two containers are running.

      [student@workstation compose-environments]$ podman-compose ps
      using podman version: ...
      podman ps -a --filter label=io.podman.compose.project=compose-environments
      CONTAINER ID IMAGE       COMMAND         CREATED    STATUS  PORTS      NAMES
      d64b...5c6f  registry... /opt/crunchy... 23 sec...  Up...   ...5050... ...pgadmin
      91ae...474e  registry... run-postgresql  23 sec...  Up...   ...5432... ...postg...
      exit code: 0

   3. Confirm that the persistent volumes exist.

      [student@workstation compose-environments]$ podman volume list
      DRIVER    VOLUME NAME
      local     91a6...f45d
      local     bd15...a5e2
      local     compose-environments_rpi
      local     f056...7eb0

      Note

      The command might display additional volumes from previous exercises.

   4. Retrieve the logs from both containers and confirm that errors are not reported in the logs. Press Ctrl+C to exit the logs.

      [student@workstation compose-environments]$ podman-compose logs -n -f
      ['podman', '--version', '']
      using podman version: ...
      podman logs -f -n compose_environments_pgadmin compose_environments_postgresql
      ...output omitted...
      compose_environments_postgresql Starting server...
      compose_environments_postgresql 2022-08-11 14:42:02.237 UTC [1] LOG:  redirecting log output to logging collector process
      compose_environments_postgresql 2022-08-11 14:42:02.237 UTC [1] HINT:  Future log output will appear in directory "log".
      ...output omitted...
      compose_environments_pgadmin Thu Aug 11 14:41:57 UTC 2022 INFO: Setting up pgAdmin4 database..
      compose_environments_pgadmin Thu Aug 11 14:42:05 UTC 2022 INFO: Starting Apache web server..

4. Access the pgAdmin interface from a web browser. Retrieve and modify data from the database.

   1. Open a web browser and navigate to http://localhost:5050. Access the pgAdmin interface as the user@example.com user with the redhat password.

   2. Click Add New Server to connect to the compose_environments_postgresql database container.

   3. In the General tab, set rpi-store as the name.

   4. Switch to the Connection tab. Complete the form with the following data and leave the rest of the fields with their default values.

      Field	Value
      Host name/address	db
      Username	backend
      Password	redhat

      Click Save. The application verifies the connection before exiting the form.

   5. Navigate to Servers → rpi-store → Databases → rpi-store, and then select Tools → Query Tool from the menu. In the Query Editor, enter the following query.

      select * from inventory

   6. Press F5 to execute the query and retrieve data from the inventory table.

      

   7. Modify the data in the inventory table. Double-click the 20 value in the quantity column. Enter 10 as the value, press Enter, and then press F6 to save the changes.

      

5. From your terminal, stop the development environment.

   [student@workstation compose-environments]$ podman-compose down
   ['podman', '--version', '']
   using podman version: ...
   ** excluding:  set()
   podman stop -t 10 compose_environments_postgresql
   compose_environments_postgresql
   exit code: 0
   podman stop -t 10 compose_environments_pgadmin
   compose_environments_pgadmin
   exit code: 0
   podman rm compose_environments_postgresql
   738f...0506
   exit code: 0
   podman rm compose_environments_pgadmin
   b584...670c
   exit code: 0