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Running PgBouncer

This tutorial will show you how to use KubeDB to run a PgBouncer.

lifecycle

Before You Begin

At first, you need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. If you do not already have a cluster, you can create one by using kind.

Now, install KubeDB cli on your workstation and KubeDB operator in your cluster following the steps here.

To keep things isolated, this tutorial uses a separate namespace called demo throughout this tutorial.

$ kubectl create ns demo
namespace/demo created

Note: YAML files used in this tutorial are stored in docs/examples/pgbouncer folder in GitHub repository kubedb/docs.

We have designed this tutorial to demonstrate a production setup of KubeDB managed PgBouncer. If you just want to try out KubeDB, you can bypass some of the safety features following the tips here.

Find Available PgBouncerVersion

When you have installed KubeDB, it has created PgBouncerVersion crd for all supported PgBouncer versions. Let’s check available PgBouncerVersion by,

$ kubectl get pgbouncerversions

  NAME     VERSION   PGBOUNCER_IMAGE                   DEPRECATED   AGE
  1.17.0   1.17.0    ghcr.io/kubedb/pgbouncer:1.17.0                22h
  1.18.0   1.18.0    ghcr.io/kubedb/pgbouncer:1.18.0                22h
  

Notice the DEPRECATED column. Here, true means that this PgBouncerVersion is deprecated for current KubeDB version. KubeDB will not work for deprecated PgBouncerVersion.

In this tutorial, we will use 1.18.0 PgBouncerVersion crd to create PgBouncer. To know more about what PgBouncerVersion crd is, please visit here. You can also see supported PgBouncerVersion here.

Get PostgreSQL Server ready

PgBouncer is a connection-pooling middleware for PostgreSQL. Therefore you will need to have a PostgreSQL server up and running for PgBouncer to connect to.

Luckily PostgreSQL is readily available in KubeDB as crd and can easily be deployed using this guide here.

In this tutorial, we will use a Postgres named quick-postgres in the demo namespace.

$ kubectl create -f https://github.com/kubedb/docs/raw/v2024.1.26-rc.0/docs/examples/pgbouncer/quickstart/quick-postgres.yaml
postgres.kubedb.com/quick-postgres created

KubeDB creates all the necessary resources including services, secrets, and appbindings to get this server up and running. A default database postgres is created in quick-postgres. Database secret quick-postgres-auth holds this user’s username and password. Following is the yaml file for it.

$ kubectl get secrets -n demo quick-postgres-auth -o yaml

apiVersion: v1
data:
  password: Um9YKkw4STs4Ujd2MzJ0aQ==
  username: cG9zdGdyZXM=
kind: Secret
metadata:
  creationTimestamp: "2023-10-10T11:03:47Z"
  labels:
    app.kubernetes.io/component: database
    app.kubernetes.io/instance: quick-postgres
    app.kubernetes.io/managed-by: kubedb.com
    app.kubernetes.io/name: postgreses.kubedb.com
  name: quick-postgres-auth
  namespace: demo
  resourceVersion: "5527"
  uid: 7f865964-58dd-40e7-aca6-d2a3010732c3
type: kubernetes.io/basic-auth

For the purpose of this tutorial, we will need to extract the username and password from database secret quick-postgres-auth.

$ kubectl get secrets -n demo quick-postgres-auth -o jsonpath='{.data.\password}' | base64 -d
RoX*L8I;8R7v32ti⏎  

$ kubectl get secrets -n demo quick-postgres-auth -o jsonpath='{.data.\username}' | base64 -d
postgres⏎ 

Now, to test connection with this database using the credentials obtained above, we will expose the service port associated with quick-postgres to localhost.

$ kubectl port-forward -n demo svc/quick-postgres 5432
Forwarding from 127.0.0.1:5432 -> 5432
Forwarding from [::1]:5432 -> 5432

With that done , we should now be able to connect to postgres database using username postgres, and password RoX*L8I;8R7v32ti.

$ export PGPASSWORD='RoX*L8I;8R7v32ti'
$ psql --host=localhost --port=5432 --username=postgres postgres
psql (14.9 (Ubuntu 14.9-0ubuntu0.22.04.1), server 13.2)
Type "help" for help.

postgres=# 

After establishing connection successfully, we will create a table in postgres database and populate it with data.

postgres=# CREATE TABLE COMPANY( NAME TEXT NOT NULL, EMPLOYEE INT NOT NULL);
CREATE TABLE
postgres=# INSERT INTO COMPANY (name, employee) VALUES ('Apple',10);
INSERT 0 1
postgres=# INSERT INTO COMPANY (name, employee) VALUES ('Google',15);
INSERT 0 1

After data insertion, we need to verify that our data have been inserted successfully.

postgres=# SELECT * FROM company ORDER BY name;
  name  | employee
--------+----------
 Apple  |       10
 Google |       15
(2 rows)
postgres=# \q

If no error occurs, quick-postgres is ready to be used by PgBouncer.

You can also use any other tool to deploy your PostgreSQL server and create a database postgres for user postgres.

Should you choose not to use KubeDB to deploy Postgres, create AppBinding(s) to point PgBouncer to your PostgreSQL server(s) where your target databases are located. Click here for detailed instructions on how to manually create AppBindings for Postgres.

Create a PgBouncer Server

KubeDB implements a PgBouncer crd to define the specifications of a PgBouncer.

Below is the PgBouncer object created in this tutorial.

apiVersion: kubedb.com/v1alpha2
kind: PgBouncer
metadata:
  name: pgbouncer-server
  namespace: demo
spec:
  version: "1.18.0"
  replicas: 1
  databases:
  - alias: "postgres"
    databaseName: "postgres"
    databaseRef:
      name: "quick-postgres"
      namespace: demo
  connectionPool:
    port: 5432
    maxClientConnections: 20
    reservePoolSize: 5
  terminationPolicy: Delete

Here,

  • spec.version is name of the PgBouncerVersion crd where the docker images are specified. In this tutorial, a PgBouncer with base image version 1.17.0 is created.
  • spec.replicas specifies the number of replica pgbouncer server pods to be created for the PgBouncer object.
  • spec.databases specifies the databases that are going to be served via PgBouncer.
  • spec.connectionPool specifies the configurations for connection pool.
  • spec.terminationPolicy specifies what policy to apply while deletion.

spec.databases

Databases contain three required fields and two optional fields.

  • spec.databases.alias: specifies an alias for the target database located in a postgres server specified by an appbinding.
  • spec.databases.databaseName: specifies the name of the target database.
  • spec.databases.databaseRef: specifies the name and namespace of the appBinding that contains the path to a PostgreSQL server where the target database can be found.
  • spec.databases.username (optional): specifies the user with whom this particular database should have an exclusive connection. By default, if this field is left empty, all users will be able to use the database.
  • spec.databases.password (optional): specifies password to authenticate the user with whom this particular database should have an exclusive connection.

spec.connectionPool

ConnectionPool is used to configure pgbouncer connection pool. All the fields here are accompanied by default values and can be left unspecified if no customization is required by the user.

  • spec.connectionPool.port: specifies the port on which pgbouncer should listen to connect with clients. The default is 5432.
  • spec.connectionPool.authType: specifies how to authenticate users.
  • spec.connectionPool.poolMode: specifies the value of pool_mode.
  • spec.connectionPool.maxClientConnections: specifies the value of max_client_conn.
  • spec.connectionPool.defaultPoolSize: specifies the value of default_pool_size.
  • spec.connectionPool.minPoolSize: specifies the value of min_pool_size.
  • spec.connectionPool.reservePoolSize: specifies the value of reserve_pool_size.
  • spec.connectionPool.reservePoolTimeout: specifies the value of reserve_pool_timeout.
  • spec.connectionPool.maxDbConnections: specifies the value of max_db_connections.
  • spec.connectionPool.maxUserConnections: specifies the value of max_user_connections.

spec.terminationPolicy

terminationPolicy gives flexibility whether to nullify(reject) the delete operation of PgBouncer crd or which resources KubeDB should keep or delete when you delete PgBouncer crd. KubeDB provides following four termination policies:

  • DoNotTerminate
  • Delete (Default)
  • WipeOut

When terminationPolicy is DoNotTerminate, KubeDB takes advantage of ValidationWebhook feature in Kubernetes 1.9.0 or later clusters to provide safety from accidental deletion of database. If admission webhook is enabled, KubeDB prevents users from deleting the database as long as the spec.terminationPolicy is set to DoNotTerminate.

Following table show what KubeDB does when you delete Postgres crd for different termination policies,

BehaviorDoNotTerminateDeleteWipeOut
1. Block Delete operation
2. Delete StatefulSet
3. Delete Services
4. Delete PVCs
5. Delete Secrets

Now that we’ve been introduced to the pgBouncer crd, let’s create it,

$ kubectl create -f https://github.com/kubedb/docs/raw/v2024.1.26-rc.0/docs/examples/pgbouncer/quickstart/pgbouncer-server.yaml

pgbouncer.kubedb.com/pgbouncer-server created

Connect via PgBouncer

To connect via pgBouncer we have to expose its service to localhost.

$ kubectl port-forward -n demo svc/pgbouncer-server 5432

Forwarding from 127.0.0.1:5432 -> 5432
Forwarding from [::1]:5432 -> 5432

Now, let’s connect to postgres database via PgBouncer using psql.

$ env PGPASSWORD='RoX*L8I;8R7v32ti' psql --host=localhost --port=5432 --username=postgres postgres
psql (14.9 (Ubuntu 14.9-0ubuntu0.22.04.1), server 13.2)
Type "help" for help.

postgres=# \q

If everything goes well, we’ll be connected to the postgres database and be able to execute commands. Let’s confirm if the company data we inserted in the postgres database before are available via PgBouncer:

$ env PGPASSWORD='RoX*L8I;8R7v32ti' psql --host=localhost --port=5432 --username=postgres postgres --command='SELECT * FROM company ORDER BY name;'
  name  | employee
--------+----------
 Apple  |       10
 Google |       15
(2 rows)

KubeDB operator watches for PgBouncer objects using Kubernetes api. When a PgBouncer object is created, KubeDB operator will create a new StatefulSet and a Service with the matching name. KubeDB operator will also create a governing service for StatefulSet with the name kubedb, if one is not already present.

KubeDB operator sets the status.phase to Running once the connection-pooling mechanism is ready.

$ kubectl get pb -n demo pgbouncer-server -o wide
NAME               VERSION   STATUS    AGE
pgbouncer-server   1.18.0    Ready     2h

Let’s describe PgBouncer object pgbouncer-server

$ kubectl dba describe pb -n demo pgbouncer-server
Name:         pgbouncer-server
Namespace:    demo
Labels:       <none>
Annotations:  <none>
API Version:  kubedb.com/v1alpha2
Kind:         PgBouncer
Metadata:
  Creation Timestamp:  2023-10-11T06:28:02Z
  Finalizers:
    kubedb.com
  Generation:  2
  Managed Fields:
    API Version:  kubedb.com/v1alpha2
    Fields Type:  FieldsV1
    fieldsV1:
      f:metadata:
        f:annotations:
          .:
          f:kubectl.kubernetes.io/last-applied-configuration:
      f:spec:
        .:
        f:connectionPool:
          .:
          f:authType:
          f:defaultPoolSize:
          f:ignoreStartupParameters:
          f:maxClientConnections:
          f:maxDBConnections:
          f:maxUserConnections:
          f:minPoolSize:
          f:poolMode:
          f:port:
          f:reservePoolSize:
          f:reservePoolTimeoutSeconds:
          f:statsPeriodSeconds:
        f:databases:
        f:healthChecker:
          .:
          f:failureThreshold:
          f:periodSeconds:
          f:timeoutSeconds:
        f:replicas:
        f:terminationPolicy:
        f:version:
    Manager:      kubectl-client-side-apply
    Operation:    Update
    Time:         2023-10-11T06:28:02Z
    API Version:  kubedb.com/v1alpha2
    Fields Type:  FieldsV1
    fieldsV1:
      f:metadata:
        f:finalizers:
          .:
          v:"kubedb.com":
      f:spec:
        f:authSecret:
    Manager:      kubedb-provisioner
    Operation:    Update
    Time:         2023-10-11T06:28:02Z
    API Version:  kubedb.com/v1alpha2
    Fields Type:  FieldsV1
    fieldsV1:
      f:status:
        .:
        f:conditions:
        f:observedGeneration:
        f:phase:
    Manager:         kubedb-provisioner
    Operation:       Update
    Subresource:     status
    Time:            2023-10-11T08:43:35Z
  Resource Version:  48101
  UID:               b5974ff8-c9e8-4308-baf0-f07bb5af9403
Spec:
  Auth Secret:
    Name:  pgbouncer-server-auth
  Auto Ops:
  Connection Pool:
    Auth Type:                     md5
    Default Pool Size:             20
    Ignore Startup Parameters:     empty
    Max Client Connections:        20
    Max DB Connections:            0
    Max User Connections:          0
    Min Pool Size:                 0
    Pool Mode:                     session
    Port:                          5432
    Reserve Pool Size:             5
    Reserve Pool Timeout Seconds:  5
    Stats Period Seconds:          60
  Databases:
    Alias:          postgres
    Database Name:  postgres
    Database Ref:
      Name:       quick-postgres
      Namespace:  demo
  Health Checker:
    Disable Write Check:  true
    Failure Threshold:    1
    Period Seconds:       10
    Timeout Seconds:      10
  Pod Template:
    Controller:
    Metadata:
    Spec:
      Container Security Context:
        Privileged:    false
        Run As Group:  70
        Run As User:   70
      Resources:
        Limits:
          Memory:  1Gi
        Requests:
          Cpu:     500m
          Memory:  1Gi
      Security Context:
        Fs Group:      70
        Run As Group:  70
        Run As User:   70
  Replicas:            1
  Ssl Mode:            disable
  Termination Policy:  Delete
  Version:             1.18.0
Status:
  Conditions:
    Last Transition Time:  2023-10-11T06:28:02Z
    Message:               The KubeDB operator has started the provisioning of PgBouncer: demo/pgbouncer-server
    Reason:                DatabaseProvisioningStartedSuccessfully
    Status:                True
    Type:                  ProvisioningStarted
    Last Transition Time:  2023-10-11T08:43:35Z
    Message:               All replicas are ready and in Running state
    Observed Generation:   2
    Reason:                AllReplicasReady
    Status:                True
    Type:                  ReplicaReady
    Last Transition Time:  2023-10-11T06:28:15Z
    Message:               The PgBouncer: demo/pgbouncer-server is accepting client requests.
    Observed Generation:   2
    Reason:                DatabaseAcceptingConnectionRequest
    Status:                True
    Type:                  AcceptingConnection
    Last Transition Time:  2023-10-11T06:28:15Z
    Message:               DB is ready because of server getting Online and Running state
    Observed Generation:   2
    Reason:                ReadinessCheckSucceeded
    Status:                True
    Type:                  Ready
    Last Transition Time:  2023-10-11T06:28:18Z
    Message:               The PgBouncer: demo/pgbouncer-server is successfully provisioned.
    Observed Generation:   2
    Reason:                DatabaseSuccessfullyProvisioned
    Status:                True
    Type:                  Provisioned
  Observed Generation:     2
  Phase:                   Ready
Events:                    <none>

KubeDB has created a service for the PgBouncer object.

$ kubectl get service -n demo --selector=app.kubernetes.io/name=pgbouncers.kubedb.com,app.kubernetes.io/instance=pgbouncer-server
NAME                    TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)    AGE
pgbouncer-server        ClusterIP   10.96.36.35   <none>        5432/TCP   141m
pgbouncer-server-pods   ClusterIP   None          <none>        5432/TCP   141m

Here, Service pgbouncer-server targets random pods to carry out connection-pooling.

Cleaning up

To cleanup the Kubernetes resources created by this tutorial, run:

$ kubectl delete -n demo pg/quick-postgres
postgres.kubedb.com "quick-postgres" deleted

$ kubectl delete -n demo pb/pgbouncer-server
pgbouncer.kubedb.com "pgbouncer-server" deleted

$ kubectl delete ns demo
namespace "demo" deleted

Next Steps