Get a PgBouncer K8s up and running

This is part of the PgBouncer K8s Tutorial. Please refer to this page for more information and the overview of the content.

In this section, you will deploy PgBouncer together with a PostgreSQL server from Charmed PostgreSQL K8s.

Deploy Charmed PostgreSQL K8s + PgBouncer K8s

To deploy Charmed PostgreSQL K8s + PgBouncer K8s, all you need to do is run the following commands:

juju deploy pgbouncer-k8s --channel 1/stable --trust
juju deploy postgresql-k8s --trust

Juju will now fetch charms from Charmhub and begin deploying them to MicroK8s. This process can take several minutes depending on how provisioned (RAM, CPU, etc) your machine is.

You can track the progress by running

juju status --watch 1s

This command is useful for checking the status of Juju applications and gathering information about the machines hosting them. It displays helpful information like IP addresses, ports, state, etc. The --watch 1s flag updates the status of charms every second, so as the application starts, you can watch the status and messages as they change.

When the application is ready, juju status will show

Model   Controller  Cloud/Region        Version  SLA          Timestamp
test16  microk8s    microk8s/localhost  3.1.6    unsupported  21:55:49+02:00

App             Version  Status   Scale  Charm           Channel    Rev  Address        Exposed  Message
pgbouncer-k8s   1.18.0   waiting      1  pgbouncer-k8s   1/stable    76  10.152.183.84  no       installing agent
postgresql-k8s  14.9     active       1  postgresql-k8s  14/stable  158  10.152.183.92  no       Primary

Unit               Workload  Agent  Address     Ports  Message
pgbouncer-k8s/0*   blocked   idle   10.1.12.15         waiting for backend database relation to initialise
postgresql-k8s/0*  active    idle   10.1.12.6          Primary

At this stage, PgBouncer will be in a blocked state due to missing relation/integration with PostgreSQL DB.

Integrate them by using the command

juju integrate postgresql-k8s pgbouncer-k8s

Shortly, juju status will report a new blocking reason Missing relation: database as it waits for a client to consume the DB service.

Let’s deploy data-integrator and request access to database test123:

juju deploy data-integrator --config database-name=test123
juju integrate data-integrator pgbouncer-k8s

In a couple of seconds, the status will be happy for the entire model:

Model   Controller  Cloud/Region        Version  SLA          Timestamp
test16  microk8s    microk8s/localhost  3.1.6    unsupported  21:57:34+02:00

App              Version  Status  Scale  Charm            Channel    Rev  Address         Exposed  Message
data-integrator           active      1  data-integrator  stable      13  10.152.183.136  no       
pgbouncer-k8s    1.18.0   active      1  pgbouncer-k8s    1/stable    76  10.152.183.84   no       
postgresql-k8s   14.9     active      1  postgresql-k8s   14/stable  158  10.152.183.92   no       Primary

Unit                Workload  Agent  Address     Ports  Message
data-integrator/0*  active    idle   10.1.12.16         
pgbouncer-k8s/0*    active    idle   10.1.12.15         
postgresql-k8s/0*   active    idle   10.1.12.6          Primary

Access database

The easiest way to access PostgreSQL is via the PostgreSQL Command Line Client psql. Connecting to the database requires that you know the values for host, username and password.

To retrieve these values, please run data-integrator action get-credentials:

juju run data-integrator/leader get-credentials

Running the command above should output:

postgresql:
  database: test123
  endpoints: pgbouncer-k8s-0.pgbouncer-k8s-endpoints.test16.svc.cluster.local:6432
  password: VYm6tg2KkFOBj8mP3IW9O821
  username: relation_id_7
  version: "14.9"

The IP address of the PgBouncer K8s’s host can be found with juju status:

...
App              Version  Status  Scale  Charm            Channel    Rev  Address         Exposed  Message
pgbouncer-k8s    1.18.0   active      1  pgbouncer-k8s    1/stable    76  10.152.183.84   no      

Make sure psql is installed with the command psql --version.

To access the PostgreSQL database via PgBouncer, use the port 6432 and your host’s IP address:

psql -h 10.152.183.84 -p 6432 -U relation_id_7 -W -d test123

Inside PostgreSQL, list DBs available on the host with show databases:

Password for user relation_id_7:  VYm6tg2KkFOBj8mP3IW9O821
psql (14.9 (Ubuntu 14.9-0ubuntu0.22.04.1))
Type "help" for help.

test123=> \l
                                     List of databases
   Name    |     Owner     | Encoding | Collate |  Ctype  |        Access privileges        
-----------+---------------+----------+---------+---------+---------------------------------
...
 test123   | relation_id_5 | UTF8     | C       | C.UTF-8 | relation_id_5=CTc/relation_id_5+
           |               |          |         |         | relation_id_7=CTc/relation_id_5+
           |               |          |         |         | admin=CTc/relation_id_5
...

You can now interact with PostgreSQL directly using any SQL Queries.

For example, entering SELECT VERSION(), CURRENT_DATE; should output something like:

test123=> SELECT VERSION(), CURRENT_DATE;
                                                               version                                                                | current_date 
--------------------------------------------------------------------------------------------------------------------------------------+--------------
 PostgreSQL 14.9 (Ubuntu 14.9-0ubuntu0.22.04.1) on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0, 64-bit | 2023-10-23
(1 row)

Feel free to test out any other PostgreSQL queries. When you’re ready to leave the psql shell, you can just type exit.

Now you will be in your original shell where you first started the tutorial. Here you can interact with Juju and MicroK8s.

Remove the user

To remove the user, remove the relation. Removing the relation automatically removes the user that was created when the relation was created. Enter the following to remove the relation:

juju remove-relation pgbouncer-k8s data-integrator

Now try again to connect to the same PgBouncer K8s you used earlier:

psql -h 10.152.183.84 -p 6432 -U relation_id_7 -W -d test123

This will output an error message because this user no longer exists.

psql: error: connection to server at "10.152.183.92", port 5432 failed: FATAL:  password authentication failed for user "relation_id_7"

This is expected, as juju remove-relation pgbouncer-k8s data-integrator also removes the user.

Relate the two applications again if you wanted to recreate the user:

juju integrate data-integrator pgbouncer-k8s

Re-relating generates a new user and password:

juju run data-integrator/leader get-credentials

You can connect to the database with these new credentials. From here you will see all of your data is still present in the database.