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Initialize PostgreSQL with Script
KubeDB supports PostgreSQL database initialization. This tutorial will show you how to use KubeDB to initialize a PostgreSQL database from script.
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
$ kubectl get ns demo
NAME STATUS AGE
demo Active 5s
Note: YAML files used in this tutorial are stored in docs/examples/postgres folder in GitHub repository kubedb/docs.
Prepare Initialization Scripts
PostgreSQL supports initialization with .sh, .sql and .sql.gz files. In this tutorial, we will use data.sql script from postgres-init-scripts git repository to create a TABLE dashboard in data Schema.
We will use a ConfigMap as script source. You can use any Kubernetes supported volume as script source.
At first, we will create a ConfigMap from data.sql file. Then, we will provide this ConfigMap as script source in init.script of Postgres crd spec.
Let’s create a ConfigMap with initialization script,
$ kubectl create configmap -n demo pg-init-script \
--from-literal=data.sql="$(curl -fsSL https://raw.githubusercontent.com/kubedb/postgres-init-scripts/master/data.sql)"
configmap/pg-init-script created
Create PostgreSQL with script source
Following YAML describes the Postgres object with init.script,
apiVersion: kubedb.com/v1alpha2
kind: Postgres
metadata:
name: script-postgres
namespace: demo
spec:
version: "10.2-v5"
storage:
storageClassName: "standard"
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
init:
script:
configMap:
name: pg-init-script
Here,
init.scriptspecifies scripts used to initialize the database when it is being created.
VolumeSource provided in init.script will be mounted in Pod and will be executed while creating PostgreSQL.
Now, let’s create the Postgres crd which YAML we have shown above,
$ kubectl create -f https://github.com/kubedb/docs/raw/v2021.01.26/docs/examples/postgres/initialization/script-postgres.yaml
postgres.kubedb.com/script-postgres created
Now, wait until Postgres goes in Running state. Verify that the database is in Running state using following command,
$ kubectl get pg -n demo script-postgres
NAME VERSION STATUS AGE
script-postgres 10.2-v5 Running 39s
You can use kubectl dba describe command to view which resources has been created by KubeDB for this Postgres object.
$ kubectl dba describe pg -n demo script-postgres
Name: script-postgres
Namespace: demo
CreationTimestamp: Fri, 21 Sep 2018 15:53:27 +0600
Labels: <none>
Annotations: kubectl.kubernetes.io/last-applied-configuration={"apiVersion":"kubedb.com/v1alpha2","kind":"Postgres","metadata":{"annotations":{},"name":"script-postgres","namespace":"demo"},"spec":{"init":{"script...
Replicas: 1 total
Status: Running
Init:
script:
Volume:
Type: ConfigMap (a volume populated by a ConfigMap)
Name: pg-init-script
Optional: false
StorageType: Durable
Volume:
StorageClass: standard
Capacity: 1Gi
Access Modes: RWO
StatefulSet:
Name: script-postgres
CreationTimestamp: Fri, 21 Sep 2018 15:53:28 +0600
Labels: app.kubernetes.io/name=postgreses.kubedb.com
app.kubernetes.io/instance=script-postgres
Annotations: <none>
Replicas: 824638467136 desired | 1 total
Pods Status: 1 Running / 0 Waiting / 0 Succeeded / 0 Failed
Service:
Name: script-postgres
Labels: app.kubernetes.io/name=postgreses.kubedb.com
app.kubernetes.io/instance=script-postgres
Annotations: <none>
Type: ClusterIP
IP: 10.108.14.12
Port: api 5432/TCP
TargetPort: api/TCP
Endpoints: 192.168.1.31:5432
Service:
Name: script-postgres-replicas
Labels: app.kubernetes.io/name=postgreses.kubedb.com
app.kubernetes.io/instance=script-postgres
Annotations: <none>
Type: ClusterIP
IP: 10.110.102.203
Port: api 5432/TCP
TargetPort: api/TCP
Endpoints: 192.168.1.31:5432
Database Secret:
Name: script-postgres-auth
Labels: app.kubernetes.io/name=postgreses.kubedb.com
app.kubernetes.io/instance=script-postgres
Annotations: <none>
Type: Opaque
Data
====
POSTGRES_PASSWORD: 16 bytes
POSTGRES_USER: 8 bytes
Topology:
Type Pod StartTime Phase
---- --- --------- -----
primary script-postgres-0 2018-09-21 15:53:28 +0600 +06 Running
No Snapshots.
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Successful 1m Postgres operator Successfully created Service
Normal Successful 1m Postgres operator Successfully created Service
Normal Successful 57s Postgres operator Successfully created StatefulSet
Normal Successful 57s Postgres operator Successfully created Postgres
Normal Successful 57s Postgres operator Successfully patched StatefulSet
Normal Successful 57s Postgres operator Successfully patched Postgres
Normal Successful 57s Postgres operator Successfully patched StatefulSet
Normal Successful 57s Postgres operator Successfully patched Postgres
Verify Initialization
Now let’s connect to our Postgres script-postgres using pgAdmin we have installed in quickstart tutorial to verify that the database has been initialized successfully.
Connection Information:
Host name/address: you can use any of these
- Service:
script-postgres.demo - Pod IP: (
$ kubectl get pods script-postgres-0 -n demo -o yaml | grep podIP)
- Service:
Port:
5432Maintenance database:
postgresUsername: Run following command to get username,
$ kubectl get secrets -n demo script-postgres-auth -o jsonpath='{.data.\POSTGRES_USER}' | base64 -d postgresPassword: Run the following command to get password,
$ kubectl get secrets -n demo script-postgres-auth -o jsonpath='{.data.\POSTGRES_PASSWORD}' | base64 -d NC1fEq0q5XqHazB8
In PostgreSQL, run following query to check pg_catalog.pg_tables to confirm initialization.
select * from pg_catalog.pg_tables where schemaname = 'data';
| schemaname | tablename | tableowner | hasindexes | hasrules | hastriggers | rowsecurity |
|---|---|---|---|---|---|---|
| data | dashboard | postgres | true | false | false | false |
We can see TABLE dashboard in data Schema which is created through initialization.
Cleaning up
To cleanup the Kubernetes resources created by this tutorial, run:
$ kubectl patch -n demo pg/script-postgres -p '{"spec":{"terminationPolicy":"WipeOut"}}' --type="merge"
$ kubectl delete -n demo pg/script-postgres
$ kubectl delete -n demo configmap/pg-init-script
$ kubectl delete ns demo
Next Steps
- Learn about backup and restore PostgreSQL database using Stash.
- Want to setup PostgreSQL cluster? Check how to configure Highly Available PostgreSQL Cluster
- Want to hack on KubeDB? Check our contribution guidelines.